A METHOD AND AN APPARATUS FOR CREATING AN OUTDOOR STILL- AIR ENVIRONMENT, OR AN ENVIRONMENT WITH CONTROLLED WIND

DESCRIPTION

Field of the invention

The present invention relates to a method and to an apparatus for creating comfort spaces in outside and inside areas, by blowing air streams.

In other words, the invention relates to a method and to an apparatus for shielding outside and inside areas from the wind or, more in general, from air streams, or for removing causes of discomfort that arise in these areas, like in case of production of unpleasant or harmful inhalable materials.

Background of the invention

The need is felt of creating comfort conditions in places intended for people to stay. By the expression "comfort", a condition of equilibrium is generally meant between a human being and the environment. In particular, the comfort conditions can comprise a still air condition, i.e. a condition in which the air speed is lower than a predetermined value which is unpleasant in case of permanence of a subject, or if a determined activity is performed by the subject. The comfort conditions can also comprise clean air conditions, in which the concentration of such undesired substances as polluting substances, smelly substances, solid particulate matter, e.g. dust, is lower than a determined threshold concentration. The comfort conditions can also comprise thermo-hygrometric equilibrium conditions, in which such physical parameters as temperature and relative humidity are set within preferable value ranges.

The need to creating comfort conditions is felt, for instance, in such wind-exposed areas as leisure places, like terraces of restaurants and bar, places intended for gymnastic exercises, or places intended for social interaction. A large number of working activities cannot be carried out in outside spaces since the presence of wind is not compatible with using work tools or leisure items such as books, documents, newspapers, paper sheets in general, and the like.

The need of a still air space is particularly felt on watercrafts, where wind conditions are created by the ship movement. Moreover, on a large number of watercrafts the problem arises of some watercraft areas, in particular poop areas, which can be smoked by the exhaust gas coming from the ship funnels, in particular in specific weather and watercraft motion conditions. For this reason, only some zones of a watercraft can be arranged for gathering, leisure or social interaction.

Furthermore, a large number of manufacturing process are known in which badly smelling, irritating or harmful products are used, or which produce fine particulate matter that is harmful. These activities are normally carried out in closed environments. In order to limit the exposition of the operators to such harmful substances, local suction devices are used, which have, however, some drawbacks. Firstly, they are not suitable for totally preventing the inhalation of the above substances. Moreover, accidental or systematic air streams, due to opening/closing doors, rolling shutters / any apertures of the room, disturb the correct operation of these suction devices.

In order to prevent people who are not involved in the work, but who are present in the room, from being exposed to the harmful substances, the areas that are dedicated to such activities are separated by panels. However, this is a costly solution, and reduces the spaces and hamper the operation within the rooms.

Furthermore, in order to use outside areas for leisure, work, sport and other activities, these areas must be shielded from comfort-reducing agents such as harmful substances, unpleasantly smelling substances, uncontrolled heat flux, but also from the action of the wind. As well known, the wind, besides being a nuisance for people, can be in turn the vector of undesired substances.

From EP0940526 a structural cell is known formed by elongated hollow elements having at least one slot for emitting jets and air curtains outwards, in order to define a thermally and acoustically insulated three-dimensional space. In an exemplary embodiment, the structural cell comprises vertical and horizontal elements interconnected and placed according to the sides of a parallelepiped. This structural cell is not suitable for removing the effects of the wind itself, in particular if the wind direction changes.

DE 199 32 153 C1 describes a device that is suitable for creating an air barrier at an entry/exit of a building, but that is not suitable for controlling the air speed in an area intended for the permanence of people, and it cannot be adjusted as the wind direction changes.

Summary of the invention

It is a feature of the present invention to provide a method for shielding i.e. for protecting an outside or an inside space from air streams, in particular from excessively fast air streams, or from streams carrying substances that are unpleasant and/or noxious for people who are present or walks through the space.

It is a particular feature of the present invention to provide a method for protecting an outside space from the action of the wind, in order to limit the discomfort that the wind can cause to people who are present in this outside space, in particular on board of a watercraft or in a leisure space such as the terrace of a coffee.

It is a particular feature of the present invention to provide a method for protecting an outside space or an inside space from streams or from the diffusion of unpleasant and/or harmful substances, in particular in workplaces or rear portions of watercrafts where a chimney is present.

It is a particular feature of the present invention to provide a method to protect people employed in activities where harmful vapours or dust are produced, more effectively than in the known methods.

It is also a feature of the present invention to provide a method for creating comfort conditions in external places that is more effective than the known methods.

It is a particular feature of the present invention to provide a method for creating general comfort conditions for people who are present in an outside space, in which further comfort parameters are controlled besides air speed and the presence of unwanted substances, such as the temperature and the relative humidity.

It is also a feature of the present invention to provide an apparatus for carrying out this method.

These and other objects are achieved by a method for creating a downwind space, wherein the downwind space includes air that has a speed lower than a wind which blows in a wind direction oriented towards the downwind space, the method comprising the steps of:

- defining a maximum admissible value for air speed in said downwind space;

defining the downwind space with respect to the direction of the wind;

prearranging an air curtain generation means of at least one air curtain between the direction of the wind and the downwind space, proximate to the downwind space,

detecting the direction of the wind;

- generating the air curtain by the air curtain generation means according to a predetermined emission direction;

- orienting the air curtain emission direction to deviate the wind at an emission angle set between 40° and 90° with respect to the direction of the wind.

This way, the wind interacts with the air curtain generated by the generation means creating a resulting air flow, i.e. a small zone where air has a direction transversal with respect to the wind, and has a speed higher than the surrounding air. This resulting air flow substantially shields a portion of space behind itself, i.e. a portion of space that is located opposite to the direction in which the wind blows, from the action of the wind. The parameters like flow rate, speed, pressure, air curtain prevalence are chosen in such a way that, in the portion of space behind, the air speed does not exceed a predetermined perception and/or acceptability air speed value, i.e. a value above which wind is perceived unpleasant for people that are present in this portion of space. According to the scientific literature, 0,7 m/s is an approximate value above which the movement of air is perceived by the human body.

By properly orienting the air curtains responsive to the direction of the wind, the position of the space portion can be predetermined where the air speed does not exceed a perception and/or acceptability threshold value, for any direction of the wind, in order to turn the space into a downwind space that is protected from external wind of any possible detectable direction. In other words, by orienting the air curtains it is possible to create a space that is always a downwind space, and is protected from a wind of any possible direction.

Therefore, the method makes it easier to use open spaces also in the presence of wind, for any recreational, work, sport activities, and the like. In particular, the method allows using open spaces also during the winter.

The air used to form the air curtains by means of the air curtain generation means can the same air of the surrounding environment, i.e. air that has the same temperature and the same relative humidity of the protected space. Optionally, it is possible to provide an air treatment in order to separate a possible suspended solid particulate matter, or to modify the relative humidity and/or the temperature.

Advantageously, a step is provided of:

generating at least two air curtains;

orienting the at least two air curtains in order to deviate the wind according to respective emission angles that are formed between the respective emission directions and the direction of the wind, at opposite sides with respect to the direction of the wind, each emission angle set in absolute value between 40° and 90°. This way, the plan of the portion of space that is always shielded, i.e. the plan of the space that is always a downwind space, is defined by a substantially closed line.

Advantageously, a step can be provided of detecting the speed of the wind and of setting the flowrate of said air curtain according to the speed of the wind and/or to the direction of the wind.

In an exemplary embodiment of the method,

the air curtains are generated along respective substantially vertical planes,

the air curtain generation means is arranged at respective edges of a right prism that encircles the downwind space;

said method comprising:

a first operation mode, in which the at least two air curtains are generated starting from two distinct edges of the prism that are adjacent to a same face of the prism;

a second operation mode, in which the at least two air curtains are generated starting from a determined edge of the prism, according to the direction of the wind;

a step of starting/maintaining the first operation mode, when the direction of the wind is oriented at an incidence angle that is narrower than a predetermined angle, called the reference angle, with respect to a direction perpendicular to a face of the prism, the face exposed to said wind, the perpendicular direction oriented towards the downwind space, the distinct edges adjacent to the exposed face, wherein the exposed face is the face of the prism at which the incidence angle has a minimum value with respect to the other faces of the prism;

a step of starting/maintaining the second operation mode when the direction of the wind is oriented at an incidence angle that is wider than the reference angle, with respect to the oriented perpendicular direction, this determined edge of the prism adjacent to the exposed face.

Said prism is preferably a regular prism, i.e. a prism that has equal faces. The prism can have any cross section, for example a square or a hexagonal cross section. By increasing the number of the sides of the cross section polygon of the prism, the downwind space approximates more and more closely a space that has a circular plan. In particular, by increasing the number of the sides and therefore the number of the edges of the prism, an increase is obtained of the ratio of the useful surface area to the surface area that is engaged by the generation means. In other words, the ratio between the surface area of the plan of the permanent downwind space and the surface area of the base of the prism increases, in particular, if the prism is a regular prism.

In particular, reference angle β* is about (360/4n)°, where n is the number of faces of the prism. For example, in the case of a square cross section, the reference angle can be about 20-25°.

Preferably, in the first operation mode the above-defined emission angle is set between 40° and 60°, more in particular, the emission angle is about 45°.

Preferably, in the second operation mode, the emission angle is set between 75° and 90°, in particular the emission angle is about 90°.

In another exemplary embodiment of the method according to the invention, a step is provided of moving at least one generation element along a path proximate to the downwind space, and the step of orienting comprises a step of arranging the generation element at a position responsive to the direction of the wind. This is advantageous since only one generator is required for creating the main air curtain, for any position of the wind. This solution reduces the size in comparison with a solution in which a plurality of fixed generation elements are provided.

In particular the path has a curvature and a centre of curvature, and the position of the generation element defines, along with the centre of curvature, an orientation direction which depends upon the direction of the wind. Preferably, the orientation direction is close or substantially coincident with the direction of the wind. For example the path can comprise an arch of circumference, i.e. it can be a circular path, in which the downwind space can have a substantially elliptical shape or, in particular, a circular shape, when it is seen in a top plan view.

In particular, the at least two air curtains are generated starting from respective generation units that are arranged at a predetermined distance, and have converging emission directions. This way, a most effective deviation is obtained of the wind which blows from outside of the zone where the downwind space is desired, in other words the air speed downwind space is more steadily maintained below a maximum predetermined value.

According to an advantageous exemplary embodiment, the method comprises a deflection stabilization step of the resulting flow formed as a combination of the air curtain with the wind, the deflection step carried out laterally with respect to the air curtain generation means at a predetermined deflection distance from the generation means. This way, a most effective wind deviation is obtained, in other words the resulting air flow comprising a combination of the wind and of the air curtains is much more stable, and therefore the still air space formed by this resulting air flow is more stable, and is protected from any outside wind.

According to another advantageous exemplary embodiment, the method comprises a step of flow extension of a combination of the air curtain with the wind, the air curtain formed by a main air curtain generation means, the extension step carried out by an auxiliary air curtain generation, i.e. an extension means that is arranged laterally with respect to the main air curtain generation means, at a predetermined extension distance from the main air curtain generation means, the extension step comprising a step of generating an auxiliary air flow according to an auxiliary emission direction that forms with the direction of the wind a predetermined extension angle. This way, under a same emission conditions of the curtain(s), it is possible to obtain a larger downwind space. Actually, this exemplary embodiment is advantageous to obtain downwind spaces of plan surface area right larger than the 4-5 m.

Hereinafter, the direction and the sense opposite to the wind is assumed as a reference for the extension angle, and the extension angle is considered positive when it is located opposite to the main air curtain generation means, and negative when arranged at the same side of the main air curtain generation means. In other words, converging extension angles are said negative, whereas diverging extension angles are said positive. For instance, the extension angle, as defined above, is set between -60° and +60°, in particular is set between -30° and +30°, preferably the extension angle is set between -15° and +15°, even more preferably it is about 0°. In particular, the auxiliary air flow and the air curtain have flowrates in a ratio set between 1/6 and 1/2, preferably auxiliary air flow and the air curtain have flowrates that are in a ratio of about 1/3.

In particular, in the above described case of air curtain generation means that are arranged at respective edges of a right prism, the second operation mode provides the step of generating an auxiliary air flow starting from edges of the prism that are adjacent to this determined edge. In other words, the air curtain generation means arranged at such adjacent edges, in the second operation mode, works as a flow extension means, i.e. as an air curtain extension means. Therefore, in an exemplary embodiment of the method, the fixed air curtain generation means can work as the main air curtain generation means or as the auxiliary air curtain generation means, i.e. as the flow extension means, responsive to the direction of the wind.

The experience has also shown that, by increasing the number of the sides and of the edges of the prism, the air curtain extension step has a better result, under the same flowrate. In fact, if auxiliary air flow is generated starting from points at a shorter distance from the wind front, a higher extension of the permanent downwind space is obtained, under a same air curtain flowrate and a same auxiliary flowrate.

According to another aspect of the invention, a step is provided of creating an artificial wind starting from a wind creation position in a closed environment or in a room, such that in this room an upwind space is formed. This way, air is moved from the upwind space towards the air curtain. The air curtain causes a deviation of the flow of the wind that is deviated according to a determined direction substantially obtaining a continuous air removal from the closed environment, i.e. from the room through said air curtain, such that a continuous air change can be provided in the upwind space. This is useful, in particular in such workplaces as car repair workshops, where operations are carried out that release noxious and/or irritating substances, or simply smelly substances. This way, the artificial wind removes continuously the undesired substances from the workshop. Furthermore, the artificial allows the operators to arrange themselves constantly upwind with respect to the areas where the undesired substances are generated, i.e. to arrange themselves upstream with respect to these generation areas, according to the direction of the artificial wind. This allows drastically limiting or completely preventing the inhalation of harmful substances. This effect is obtained most effectively if the operators turn the back to the wind, i.e. to the artificial wind creation means.

The undesired substances are conveyed by the artificial wind towards the air curtains, and then are conveyed by the air curtains towards a peripheral zone of the room, or in any case towards a place in which a vapour collection means or a solid particulate matter separation means can be arranged, for example a cyclone separation means.

The aria collected by collection means, which can be purified by the separation means, can be advantageously recycled to the suction side of the artificial wind creation means. This allows limiting thermal losses from the room to the outside.

In particular, a step is provided of moving the wind creation position to form a movable upwind space within the closed environment. This way, upwind spaces of relatively small extension can be created, which further reduces the costs and limits the disadvantages for the operators who are not involved in the potentially harmful operations.

The creation of an artificial wind has the advantage that the air speed field in the upwind space is substantially independent from air streams that regularly or accidentally come from apertures of the room, such as doors, windows, etc. Therefore, the unwelcome substances removal efficiency is independent from these air streams, which is not the case in the conventional suction systems arranged at the emission points of the undesired substances.

In particular the downwind space is an outside space of a watercraft. This allows limiting the discomfort that the relative movement of air with respect to the watercraft causes, for instance, to people who are present in an leisure area of the watercraft. This discomfort can occur, for example, in a watercraft standing in a windy zone, or in a watercraft in motion, even if no wind is blowing, due to the watercraft motion itself, even at a speed that is commonly attained by a cruise ship. A further advantage is provided if the downwind space, according to the invention, is created in a depression area of the ship, for instance in a zone behind structures arising on the watercraft which, during the movement of the watercraft, can be smoked by exhaust gas sucked from funnels. By arranging an apparatus with an suitable orientation of the generation means, the smoke can be maintained far from such a zone.

The above mentioned objects are reached also by an apparatus for creating a downwind space, wherein the downwind space includes air that has a speed lower than a wind which blows according to a direction oriented towards the downwind space, in a predetermined location with respect to a direction of the wind, the apparatus comprising:

- an air curtain generation means for generating at least one air curtain, the air curtain having, at the generation means, a predetermined emission direction;

- a wind direction detection means for detecting the direction of the wind;

- an orientation means for orienting the air curtain emission direction to deviate the wind, according to an emission angle set between 40° and 90° with respect to the direction of the wind.

Advantageously, the air curtain generation means is configured to generate at least two air curtains to deviate the wind, according to respective emission angles at opposite sides with respect to the direction of the wind, each emission angle in absolute value set between 40° and 90°.

Advantageously, the apparatus comprises a means for detecting the speed of the windand adjustment means for adjusting the flowrate of said air curtain. In particular, a flowrate adjustment means is provided for adjusting the automatically adjusting the flowrate responsive to the speed of the wind and/or to the direction of the wind.

The air curtain generation means can comprise prior art devices, for instance they can comprise vertically arranged longitudinal generation elements that have an inner recess for receiving an air flow and slits or holes arranged to one another along an own generatrix for emitting this air in the form of an air curtain. Furthermore, these elements can have a rotation means for turning about an own longitudinal axis, in order to orient the air curtain according to a predetermined angle about this longitudinal axis. Furthermore, the air curtain generation means can comprise one or more fans provided with respective suction mouths that are pneumatically connected with the outside environment, and that are provided with respective delivery mouths that are pneumatically connected with the inner recess or with emission slits or emission holes of the air curtains generation longitudinal elements.

In an exemplary embodiment of the apparatus according to the invention, the air curtain generation means is configured to form air curtains along respective substantially vertical planes, and comprises a plurality of generation modules arranged at respective edges of a right prism that encircles the downwind space;

the orientation means configured to actuate:

a first operation mode, in which the at least two air curtains are generated by two generation modules arranged at two distinct edges of the prism that are adjacent to a same face of the prism;

a second operation mode, in which the at least two air curtains are generated by a same generation module arranged at a determined edge of the prism, responsive to the direction of the wind;

said orientation means also configured to:

- start/maintain the first operation mode, when the wind direction detection means detects that the direction of the wind is oriented at an incidence angle that is narrower than a predetermined angle, called the reference angle, with respect to a direction perpendicular to a face of the prism, the face exposed to said wind, the perpendicular direction oriented towards the downwind spaces, the distinct edges adjacent to the exposed face, wherein the exposed face is the face of the prism where the incidence angle has a minimum value with respect to the other faces of the prism;

- start/maintain the second operation mode when the wind direction detection means detects that the direction of the wind is oriented at an incidence angle wider than the reference angle with respect to the oriented direction perpendicular, this determined edge of the prism adjacent to the exposed face.

The prism can have the features that were described along with the method, with the advantages which were also highlighted. Similarly, the values of the reference angle and of the emission angle, in the two operation modes, have been already mentioned while describing the method, along with the respective advantages.

In another exemplary embodiment of the apparatus, according to the invention,

the air curtain generation means comprises a movable generation element configured to move along a path proximate to the downwind space;

the orientation means comprise an actuation means of a movement of the generation element along this path, the actuation means configured to arrange the generation element at a position responsive to the direction of the wind.

The details of the shape of the path and of the orientation angle, which have been provided when describing the method according to the invention, also define advantageous exemplary specific embodiments of the apparatus, to which reference is made here.

Therefore, the orientation means comprises a means for switching on/off the fixed generation modules, and/or a means for controlling the position of the movable generation element.

Advantageously, the orientation means can also be associated with a control means for controlling the flowrate or the speed of the air curtains through emitted by the generation means.

In particular,

the generation element comprises two generation units that are arranged at a predetermined distance, and are configured to emit one of the at least two air curtains in such a way that the emission directions are converging directions. This allows a more effective stabilization of the downwind space.

According to an advantageous exemplary embodiment, the apparatus comprises a flow deflection means that is arranged laterally with respect to the generation means, at a predetermined deflection distance from the generation means, in order to more effectively stabilize the downwind space according to a predetermined angle.

In an advantageous exemplary embodiment, the air curtain generation means is configured to emit the at least two air curtains in such a way that the emission directions are diverging directions, and the deflection means comprises a couple of deflection elements arranged at opposite sides with respect to the generation means.

In alternative, the generation element comprises two generation units that are arranged at a predetermined distance, and that are configured to emit a respective of the at least two air curtains such that the emission directions are converging directions and the deflection means comprises a central deflection element located between the generation units.

In another advantageous exemplary embodiment, the apparatus comprises a flow extension means that is arranged laterally with respect to the main air curtain generation means, at a predetermined extension distance from the main air curtain generation means, the extension means comprising an auxiliary air curtain generation means that is configured to form an auxiliary air flow according to an auxiliary emission direction that forms a predetermined extension angle with the direction of the wind.

Preferably, the extension angle, as above defined, is set between -60° and +60°, in particular is set between -30° and +30°, more in particular is set between -15° and +15°,evenmore in particular, the extension angle is about 0°. As already observed, this exemplary embodiment allows obtaining larger downwind spaces under same main air curtains, i.e. under same air curtains generated by the main air curtain generation means.

Advantageously, the auxiliary air curtain generation means are configured to form an auxiliary air flow that has a flowrate set between 1/6 and 1/2 of the flowrate of the air curtain, in particular a flowrate of about 1/3 of the flowrate of the air curtain.

Preferably, the air curtain generation means has suction mouths that are configured to cause the air suction laterally with respect to the generation means, according to a predetermined direction. This way, in the regions between main air curtain generation means and each auxiliary air curtain generation means a turbulent air circulation zone is formed, which cooperates with the resulting air flow to stabilize the still air space. This effect can be assisted by arranging the auxiliary air curtain generation means, in such a way to form negative extension angles, i.e. oriented according to converging auxiliary emission directions opposite to the downwind spaces with respect to the apparatus. It falls within the scope of protection also a watercraft comprising an apparatus for creating a downwind space as previously described, in an outside area on board of the watercraft.

In particular, the deflection means are movable integrally with the movable generation element. The deflection means can be mechanically connected to the movable generation element by means of well-known systems, for instance the deflection means and the generation element can be mounted on a same plate that can move along the path.

In particular, the flow extension means is movable integrally with the movable generation element. The extension means can be mechanically connected to the movable generation element by means of well-known systems, for example the extension means and the generation element can be mounted on a same movable plate along the path.

The apparatus can comprise or can be associated with a weather station that is configured to detect, besides the wind direction, a parameter selected among the speed of the wind, the temperature of surrounding air, the relative humidity of the environment, i.e. of surrounding air and/or of the air included in the downwind space, and to provide a display or an electric signal of this parameter or of any of these parameters.

The apparatus can also comprise a computing means configured to receive this or any signal, and to calculate, responsive to this or to any signal, a thermal radiation power to be supplied to the downwind space and/or an amount of nebulised water to be sprayed into the downwind space according to an algorithm for computing an optimum physiological comfort condition.

Advantageously, the apparatus comprises a means for supplying the power, for example at least one conventional radiation lamp, and/or a hydraulic means for sprinkling the nebulised water, such thermal or and/or hydraulic means functionally connected to the computing means of the apparatus, for receiving a control signal of irradiation/water spraying responsive to the detected weather parameters.

Advantageously, the computing means comprises a feedback control means to control the heat means and/or the hydraulic means, configured for substantially real-time adjusting the power that is irradiated and the water that is nebulised into the downwind space.

In other words, the computing means can also be configured to carry out an algorithm to control, besides the air curtains emission conditions, in particular the emission place and direction, the temperature and the relative humidity in the downwind space, for instance, independently from each other. According to another aspect of the invention, a means is provided for creating an artificial wind and an upwind space, the creation means arranged in a wind creation position in a room or in a closed environment, configured to move air from the upwind space towards the air curtain, and to cause a continuous air removal from the closed environment, i.e. from the room, through said air curtain, such that a continuous air change can be provided in the upwind space.

The creation means can be a movable creation means, to form a movable upwind space within the closed environment. Similarly, also the air curtain generation means can be configured for moving synchronously with the artificial wind creation means.

In an exemplary embodiment, the artificial wind creation means and the air curtain generation means are arranged along concentric paths around the closed environment, to form an upwind annular space within the closed environment.

Brief description of the drawings

Further characteristic and advantages of the method and of the apparatus according to the invention will be made clearer with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings, in which:

Fig. 1 diagrammatically shows an apparatus according to an exemplary embodiment of the invention, in which a means is provided for generating at least one air curtain;

Fig. 2 diagrammatically shows an apparatus according to an exemplary embodiment of the invention, in which a means is provided for generating at least two air curtains;

Figs. 3 and 4 diagrammatically show two apparatus according to further exemplary embodiments of the invention, comprising a plurality of generation modules arranged at the edges of a prism that has a square and a hexagonal cross section, respectively;

Fig. 5 shows the apparatus of Fig. 3 in a first operation mode, according to the invention;

Fig. 6 still shows the apparatus of Fig. 3 in a second operation mode, according to the invention;

- Figs. 7 and 8 diagrammatically show an apparatus according to an exemplary embodiment of the invention, in which a movable air curtains generation element is provided, in two positions corresponding to two different directions of the wind; Figs. 9 and 10 show an apparatus according to an exemplary embodiment of the invention in which the air curtain generation means comprises two movable generation elements, in two positions corresponding to two different directions of the wind;

- Figs. 11 and 12 diagrammatically show apparatuses, according to two exemplary embodiments of the invention, which comprise a deflection means for deflecting the air curtain generated by the generation element or by the generation elements, respectively;

- Figs. 13, 14 and 15 diagrammatically show an apparatus, according to an exemplary embodiment of the invention, in which a generation means is provided that comprises a fixed main generator and an auxiliary generation means that are configured to cause a flow extension or are configured to form a turbulent circulation, where the main generator and the auxiliary generators emit air flows according to different orientations;

- Figs. 16, 18 and 19 diagrammatically show apparatuses according to further exemplary embodiments of the invention, in which a movable generation means is provided that comprises a main generation element and an auxiliary generation means, as shown in Fig. 13-15;

Fig. 17 shows an apparatus comprising movable generators which is similar to the apparatus shown in Figs. 16-19, in a use for a terrace in an open space;

- Figs. 20, 21 , 22 diagrammatically show an apparatus, according to an exemplary embodiment of the invention, which comprises an air curtain generation means that is arranged at the edges and at the middle planes of the faces of a square cross section prism, in three exemplary embodiments of a first operation mode;

- Fig. 23 diagrammatically shows the apparatus of Figs. 20,21 ,22 in a second operation mode;

Fig. 24 diagrammatically shows an apparatus similar to the apparatus of Figs. 20 and 23, in which the prism cross section is hexagonal;

Fig. 25 diagrammatically shows an arrangement of generators, according to the principle of Figs. 20-24, to create a downwind space that has a complex shape;

Fig. 26 diagrammatically shows an apparatus, according to an exemplary embodiment of the invention, to provide an air change in a room by means of a zone in which an artificial wind is created, and of a couple of air curtains;

Fig. 27 diagrammatically shows an apparatus according to the principle of Fig. 26, in which the artificial wind zone can be displaced in the room;

- Figs. 28 and 29 diagrammatically show apparatuses in which the artificial upwind zone made can be displaced within the closed environment, respectively along an arch of a circumference and a circumference;

Fig. 30 diagrammatically shows the downwind space, i.e. the still air space obtained, for instance, by the apparatus of Fig. 2, for various directions of the wind;

- Fig. 31 shows the permanent downwind space that can be obtained by the apparatus of Fig. 2 according to the operation of Fig. 30;

Figs. 32 and 33 show generation modules or elements that are suitable for building the apparatus;

Fig. 34 shows the limit speed profile that is obtained, for a given wind direction, by means of the apparatuses shown in Figs. 13-19;

Figs. 35 and 36 diagrammatically show in a top plan view the generation module of Fig. 32 or, equivalently, the generation module of Fig. 33, with two different orientations of the suction mouths;

Fig. 37 shows the limit speed profile that is obtained, for a given direction of the wind, in case of lateral air suction by the generators;

Fig. 38 is a perspective view of a apparatus similar to apparatus of Fig. 16-19, having generation modules as shown in Fig. 32;

Fig. 39 shows a watercraft that is equipped with an apparatus according to the invention, for creating a still air space in an outside space on board of this watercraft.

Description of preferred exemplary embodiments

With reference to Fig. 1 , an apparatus 1 is described for creating a still air space i.e. a downwind space 10, i.e. a space where the air has a speed lower than the speed of wind 11 , that outside of downwind space 10 has an untreated wind direction 1 ', in order to create comfort conditions for people who are present in or pass through still air space 0.

According to the invention, apparatus 1 comprises an air curtain generation means 12 that is configured to generate at least one air curtain 13 according to a predetermined emission direction 14, in order to form an emission angle a set between 40° and 90° between wind direction 11 ' and emission direction 14.

Optionally, apparatus 1 further comprises a direction detection means 41 for detecting wind direction 1 '.

Still optionally, apparatus 1 can also comprise a speed direction detection means 41 ' for detecting the speed of wind 1 .

In a preferred exemplary embodiment, wind direction 1 V detection means 41 can be operatively connected to a means 42 of apparatus 1 for orienting air curtain 13 against direction 11 ' of wind 11 , in order to form an emission angle a set between 40° and 90° between wind direction 11' and emission direction 14.

Furthermore, detection means 41' of the speed of wind 11 can be operatively connected to a means 42' of apparatus 1 for adjusting parameters of the air curtain, e.g. the speed and the flow rate.

In a possible exemplary embodiment, direction and speed detection means 41 and 41' are configured to cooperate with means 42,42' for controlling the orientation and the speed/flow rate.

In the most general embodiment of the invention, wind 11 interacts with air curtain 13 that is generated by air curtain generation means 12, which creates a resulting air flow 15 that is capable of shielding by the wind the portion of space 10 behind air curtain generation means 12 of the part starting the flow resulting same 15, i.e. A portion of space 10 located opposite to direction 11' of provenience of wind with respect to the resulting air flow 5, creating in this portion of space still air space 10.

Wind direction 11' detection means 41 , and the possible wind speed detection means 41 ' can advantageously, belong to a weather station 50 that is configured to detect, in addition to wind direction 11', the speed of wind 11 and a parameter of the surrounding air, such as the relative humidity and/or the temperature. In this case, weather station 50 can comprise a means for displaying this or any parameter detected by weather station 50.

In alternative, or in addition, weather station 50 can be configured to emit an electric signal for this or any condition, and the apparatus can comprise a computing means 42 that is configured to receive this or any signal and to execute an algorithm for computing a physiological comfort condition.

This algorithm, which can be easily implemented by a skilled person, is advantageously configured to calculate a thermal radiation power to be supplied to the downwind space and/or an amount of nebulised water to be sprayed into the downwind space, according to reference comfort conditions such as hygrometric conditions, thermal conditions and the like. In this case, the apparatus can also comprise a means for supplying a thermal power to the downwind space, typically in the form of a thermal radiation power, for example electric resistance or gas heaters, and a means for supplying an amount of nebulised water, not shown.

Advantageously, computing means 42 is configured to emit a control signal according to the radiation power and by the amount of nebulised water, and the means for supplying thermal power and nebulised water have an actuation means that is configured to receive the control signal and to supply a power and an amount of water according to the control signal. In a possible embodiment of the invention, an apparatus can be provided or associated only with a detection means 41 ,41' of direction 11' and/or the speed of wind 11 , which can receive an instruction by an operator, who receives the direction of the wind and decides to change accordingly the orientation of air curtain generation means 12, and preferably also to change the speed of the air curtain. As an alternative, the change of the orientation of air curtain generation means 12, and preferably also the change of the speed of the air curtain, can be carried out automatically, according to the values of direction 11 ' and/or of speed of wind 11.

With reference to Fig. 2, an apparatus 2 is described, according to the invention, in which air curtain generation means 12 are configured to generate two air curtains 13', 13" generally in opposition to wind 11 , according to respective emission angles α', a" that are opposite to each other and are preferably symmetrical with respect to direction 11' of wind 11. In accordance with what has been described above, each emission angle α',α" is set between 40° and 90°. In this case, the resulting air flow comprises two branches 15' and 15" that are preferably symmetrical and are arranged at opposite sides with respect to wind direction 11 '. Similarly to Fig. 1 , a detection means 41 ,41' can be provided for detecting direction 11 ' and/or the speed of wind 11 , a microprocessor 42 and a possible weather station, not shown.

With reference to Figs. 3 and 4, apparatuses 3, 3' are described according to the invention, each of which comprises a plurality of generation modules 20, which are similar to air curtain generation means 12 of Figs. 1 and 2, that are arranged at respective edges 16 of a right prism 51 , the prism having a polygonal cross section, for example a square (Fig. 3), a pentagonal, a hexagonal (Fig. 4), an octagonal cross section and the like. Air curtain generation means 20 is configured to form air curtains, not represented, such as air curtains 13, 13', 13" of Figs. 1 and 2, along respective substantially vertical planes.

With reference to Figs. 5 and 6, the operation of the apparatus 3 of Fig. 3 is described. The operation mode described in the case of square cross section prism 51 can be extended in an obvious way to the case of any number of sides of the polygon which forms the cross section of prism 51. In a first operation mode (Fig. 5), two air curtains 13',13" are generated through two generation modules 20 that are arranged at two distinct edges 16', 16" of prism 51 adjacent to a same face 17' of prism 51. In a second operation mode (Fig. 6), air curtains 13', 3" are generated through a same generation module 20 that is arranged at a predetermined edge 16 of prism 51.

The first operation mode (Fig. 5) is started/maintained when detection means 41 (not shown and similar to the one of Fig. 1) detects that wind 11 forms an incidence angle β with the direction 18 perpendicular to exposed face 17', which is narrower than a predetermined limit angle, called reference angle β*.

In the case of Fig. 5, incidence angle β is substantially 0. Edges 16', 16" starting from which air curtains 13', 13" are generated, are adjacent to face 17', which is the face of prism 51 at which incidence angle β has the minimum value, with respect to the angles formed with the directions perpendicular to the other faces 17 that are exposed to wind 11 , in this case a substantially right angle. Air curtains 3', 13" are generated according to respective directions 14', 14" opposite to each other. They can form with direction 1 ' of wind 11 an emission angle a set between 40° and 90°, preferably set between 40° and 60°. In particular, Fig. 5 shows an emission angle a of about 45°.

The second operation mode (Fig. 6) is started/maintained when detection means 41 detects that wind 11 forms an incidence angle β with perpendicular direction 18 that is wider than incidence angle β*. Edge 16 starting from which air curtains 13', 13" are generated is adjacent to exposed face 17'. Fig. 6 shows an emission angle a of about 90°.

In the second operation mode, emission angle a is preferably set between 75° and 90°, in particular emission angle a is about 90°.

With reference to Figs. 7 and 8, an apparatus 4 is described according to another exemplary embodiment of the invention, in which the air curtain generation means comprises a generation element 19 that can move along a path 24 proximate to downwind space 10. Path 24 can be defined by a rail, by a slide, by a rack device, by a magnetic guide system, by any other system of known type. An orientation means, not shown, is advantageously provided, and an actuation means for actuating a movement of generation element 19 along path 24, for example a motor means associated with a rail, which are configured to arrange generation element 19 at a position 21 responsive to direction 1' of wind 11 , and which can also be configured to adjust the flowrate or the output speed of the air curtains.

Path 24 can have any open or closed shape, for example it can have an elliptical shape. In particular, in the depicted exemplary embodiment, path 24 is a substantially circular path. In this case, it is possible to create a downwind space 10 that has a substantially circular plan. However, the operation mode of apparatus 4 can be extended in an obvious way to the case of any path that is at least in part curvilinear, closed or open, and that has, at least locally, a centre of curvature 22. Position 21 defines, along with centre of curvature 22, an orientation direction 23 responsive to wind direction 11', in particular orientation direction 23 can be close or substantially coincident with wind direction 11 '.

With reference to Figs. 9 and 10, an apparatus 5 is described according to the invention, in which generation element 19 comprises two generation units 19', 19" that are arranged at a predetermined distance B from each other. Generation units 19', 19" are configured to emit respective air curtains 13',13" that have converging emission directions 14', 14". Similarly to apparatus 4 of Figs. 7 and 8, generation element 19 can move along a path 24 proximate to downwind space 10, according to an orientation direction 23 responsive to wind direction 11 '.

With reference to Figs. 1 1 and 12, two apparatuses 6 and 6' are described as further exemplary specific embodiments of the invention. Apparatuses 6,6' comprise a flow deflection means 27,27',27" that is arranged laterally with respect to the generation means, i.e. with respect to generation unit 19, or to generation units 19', 19", at a predetermined deflection distance D from the generation means.

According to the exemplary embodiment of Fig. 11 , generation unit 19 is configured to emit air curtains 13', 13" with diverging emission directions 14', 14", and a couple of deflection elements 27',27" is provided arranged at opposite sides with respect to generation unit 19.

Instead, according to the exemplary embodiment of Fig. 12, a single central deflection element 27 is provided that is located between two generation units 19', 19" that are configured to generate air curtains 13', 13" according to converging directions 14', 14", with respect to each other.

Even if not depicted, an exemplary embodiment of the apparatus is possible according to the invention, in which a fixed generation means 12 is provided, as shown in Fig. 3, which comprise a deflection means 27,27',27" as shown in Fig. 1 1 or in Fig. 12.

In apparatuses 6,6', deflection means 27,27',27" is movable integrally or synchronously with respect to the movable generation element 19. Deflection means 27,27',27" can be mechanically connected to the movable generation element by means of well-known systems, for example the deflection means and the generation element can be mounted on a same base frame, not shown, which can move along path 24.

With reference to Figs. 13, 14 and 15, an apparatus 7 is described, according to an advantageous exemplary embodiment of the invention. Apparatus 7 comprises an auxiliary air curtain generation means 29 that is arranged laterally with respect to air curtain generation means 12, at a predetermined distance from the latter. The auxiliary air curtain generation means 29 is configured to form an auxiliary air flow 31 with an auxiliary emission direction 26. Auxiliary emission direction 26 forms a predetermined extension angle γ with direction 1 1 ¹ of wind 1 1.

Preferably, as shown in Fig. 13, extension angle γ is about 0°, i.e. auxiliary air flow 31 is directed against the wind. In other exemplary embodiments, as shown in Figs. 14 and 15, extension angle γ is about 45°, still in opposition to direction 1 1 ' of wind 1 1.

The exemplary embodiment of Figs. 13, 14 and 15 allows obtaining larger downwind spaces 10, at the same emission conditions of air curtains 13',13" from main air curtain generation means 12. In fact, by operating the auxiliary air curtain generation means 29, resulting air flows 15,15', which are formed by the respective union of air curtains 13', 13" and wind 1 1 , and which are symmetrical and directed against the direction of the wind, become wider and change qualitatively as shown in Fig. 34, according to branches 55', 55" of Fig. 34. This way, a still air space 10 is obtained that is wider and more stable than in the case of an apparatus in which only main air curtain generation means 12 are provided.

In particular, in the case of an apparatus comprising fixed generation modules at the edges of a prism, the second operation mode comprises the step of generating auxiliary air flow 31 starting from prism edges 36',36" that are adjacent to edge 16 starting from which air curtains 13', 13" are generated. In other words, the generation modules arranged at these adjacent edges, in the second operation mode, can work as auxiliary air curtain generation means. Therefore, in an exemplary embodiment of the method, the fixed generation modules can work as main air curtain generation means or as auxiliary air curtain generation means, depending upon the direction of the wind.

In particular, auxiliary air flow 31 and the air curtain have a flowrate ratio set between 1/6 and 1/2, in particular a ratio of about 1/3.

With reference to Figs. 16,18,19, the concepts underlying the exemplary embodiment of Figs. 13, 14 and 15 can be extended to the case of an apparatus 8',8",8"', according to an exemplary embodiment of the invention, that is provided with a generation element 19 movable along a path 24. Apparatus 8',8",8"' comprises a flow extension means 29 that is movable integrally or at least synchronously with movable generation element 19. Auxiliary air curtain generation means 29 can be mechanically connected to the movable generation element by means of well-known systems, for example auxiliaryair curtain generation means 29 and generation element 19 can be mounted on a same base frame, not shown, which is movable along path 24. The reference numbers and the other symbols used in Figs. 16,18,19 have the same meaning as in Figs. 13, 14 and 15;

Fig. 17 shows a use of apparatus 8' of Fig. 16 for creating a downwind space or a comfort outside space, for example on a terrace 57 that extends from a wall 56, typically a terrace of a coffee or a smokers' space;

Figs. 13, 14 and 15, as well as Figs. 16, 18 and 19, differ from one another in the value of emission angles α', a", both respectively about 0°, about 90° and about 45°, and/or in the value of extension angle γ. In a preferred exemplary embodiment, angles α', a" are about 45°, whereas extension angle γ is about 0°, as shown in Figs. 13 and 16.

With reference to Figs. 20 to 23, an apparatus 9 is described, according to an exemplary embodiment of the invention, in which air curtain generation means 12 comprise generation elements 20 that are arranged at the edges 46 of a right prism, in this case a square cross section prism 51 , and also comprise generation elements 20' that are arranged at an intermediate position of the faces of prism 51 , in this case at middle line 47 of these faces.

In particular, figures from 20 to 22 diagrammatically show a first operation mode of apparatus 9, in which two air curtains 13', 13" are generated through a generation module 20' that is arranged at middle line 47 of a face 57 of prism 51 , with emission angles α', a" set between 40° and 90°.

Advantageously, as shown in the drawings, emission angles α', a" can be about 45°. Furthermore, air curtain generation means 20, which is arranged at the edges defining face 57, works in this case as an auxiliary air curtain generation means that emits auxiliary air streams 31 according to auxiliary emission direction 26. For the auxiliary emission, an extension angle γ set between -60° and +60° can be formed with direction 1 1 ' of wind 11.

In the preferred exemplary embodiment of Fig. 20, extension angle γ is about 0°, i.e. auxiliary air flow 31 is directed against the wind. In other exemplary embodiments, as shown in Figs. 23', 17", angles of -45°, +45° are respectively shown.

Instead, Fig. 23 shows a second operation mode of apparatus 9, in which two air curtains 13', 13" are generated through a generation module 20 that is arranged at an edge 46 of prism 51 , according to emission angles α', a" set between 40° and 90°.

Advantageously, as shown in this drawing, emission angles α', a" are about 90°. Furthermore, air curtain generation means 20' arranged at middle lines 47 of the faces adjacent to edge 46 operate in this case as auxiliary generation elements, which emit auxiliary air streams 31 according to respective auxiliary emission directions 26. Auxiliary directions 26 can form an extension angle γ set between -60° and +60° with direction 11' of wind 11 , advantageously, as shown in this drawing, an angle of about +45°. Further auxiliary air flows 31' can be emitted by generation elements 20 that are arranged at edges 46' that define, along with edge 46, respective faces of prism 51 , preferably according to a further auxiliary direction 26' parallel to the auxiliary direction 26.

Apparatus 9 is provided with a switch means for switching from the first operation mode (Fig. 20-22) to the second operation mode (Fig. 23), or vice- versa, when an incidence angle on an exposed face of prism 51 becomes higher or becomes lower than a predetermined lower threshold value i.e. than a reference angle β*, respectively, as described with reference to Figs. 5 and 6. The operation mode described with reference to Figs. 20-23 can be generalized in an obvious way to the case of a prism that has a cross sectional shape other than a square shape, for example a hexagonal or an octagonal cross section, or the like.

Figs. 24 and 25 show two apparatuses 9', 9" according to respective exemplary embodiments of the invention. In particular, an apparatus 9' is shown in Fig. 24 in which generation modules 20,20' are arranged at edges 46 and at intermediate positions 47, respectively, along faces of a right prism 52 that has a hexagonal cross section. Instead, Fig. 25 diagrammatically shows an apparatus 9" in which generation modules 20,20' are arranged at edges and at intermediate positions, respectively, along faces of an irregular prism 53, which is obtained by face-to-face joining prisms that have a square cross section, in order to conform the shape of downwind space 10 to particular needs.

With reference to Figs. 26 to 29, apparatuses 58,59 are described, as further exemplary embodiments of the invention, in which a means 33 is provided for creating an artificial wind 11 in a closed environment or in a room 30, between a creation position 37, and at least one air curtain 13', 13" that is generated frontally with respect to creation position 37, for example frontally with respect to a wall of room 30. The means for creating artificial wind 11 can be, for instance, conventional fans 33. This way, room 30 is divided into an upwind space 30", and a downwind space or zone 30'. Artificial wind 11 , associated with air curtains 13', 13" causes a movement of air from upwind space 30" towards air curtains 13', 13", and therefore causes a directional air change. Artificial wind 11 , along with air curtains 13', 13", creates a controlled air flow upwind spaces 30", which allows people who are present to arrange themselves in such a way to minimize or to eliminate their own exposition to noxious or undesired substances, and which allows removing noxious substances or in any case undesired substances, such as vapour and fine particulate matter, which are released when manufacturing a piece 39'. The noxious substances are stored into collection spaces 38. In summary, the device shown in Figs. 26-30 allows dividing the space into an upwind space, where air is present that has not been treated and is therefore potentially harmful, and into a downwind space, where substantially clean air is present.

In a position along air curtains 13', 13", at a predetermined distance from air curtain generation means 12, an air collection means 38 is arranged to collect air that comes from upwind space 30" through air curtains 13', 13". The collection means can comprise, in particular, a separation means, for example cyclone separation means, not shown, for separating and collecting solid particulate matter entrained by air coming from upwind space 30". The collection means can also comprise a filter means and/or a pollutant reduction means. Collection means 38, and/or the separation means, can be associated with a duct 43 for recycling purified air to the suction side of fans 33. Upwind space 30" can be a zone of a workshop arranged for operations that take place with use and/or production of noxious and/or irritating and/or smelly substances or in any case undesired substances, such as solvents, residues of paints, solid particulate matter and the like. For instance, upwind space 30" can be arranged to paint articles 39', for example fibreglass reinforced plastic structures that have a significant surface extension, such as watercrafts. Instead, downwind space 30' is advantageously arranged for operations in which there is no production and/or use of these substances. Due to air curtains 13',13", along with artificial wind 1 1 , downwind space 30' is not substantially affected by the presence of the undesired substances in use and/or produced in upwind space 30". For example, downwind space 30' can be arranged as a storage place for storing articles 39" awaiting further processing to be carried out in upwind space 30".

As shown in Figs. 27-29, creation means 33 of artificial wind 11 and air curtain generation means 12 of air curtain 13', 13" can be movable, in order to form an upwind space 30" that can be displaced within the closed environment. For instance, air curtain generation means 12 of air curtain 13', 13", along with collection means 38, can be mounted on a movable means 44 that can shift along a path 45. In particular, movable means 44 can be a carriage or a slide, and path 45 can be defined by a rail or by a slide guide means.

In the exemplary embodiment of Fig. 29, a creation means 33 for creating artificial wind 1 1 and air curtain generation means 12 for creating air curtain 13', 13" are arranged along concentric arcs 34', 34" within closed environment 30, to form an upwind annular space 30' within closed environment 30.

With reference to Fig. 32, a device 60 is described for generating two air curtains, which is arranged to provide air curtain generation means 12 of the apparatus according to the invention, i.e. to provide fixed generation modules 20,20' (Figs. 3-6, 20-25) or movable generation modules 19 (Figs. 7-12 and 16- 19) according to previously described exemplary embodiments. In particular, generation device 60 has a shape elongated along an axis 62, and comprises a double plurality of fans 61 that arranged to form two parallel stacks 60'. Fans 61 can be conventional centrifugal fans, which are associated with air conveying means to obtain air curtains 13', 13". They can comprise delivery mouths 66 that have a rectangular cross section, and which are arranged with the longer sides parallel to axis 62, in order to define two air blowing zones to form portions 65 of air curtains 13', 13".

In a preferred exemplary embodiment, device 60 comprises an orientation means, not shown, for orienting the two stacks of fans 61 about respective rotation axes 64, for example independently from each other, in order to orient the air blowing zone consisting of mouths 66 and, accordingly, to orient air curtains 13', 13".

With reference to Fig. 33, a device 70 is described for generating two air curtains 13', 13", which is arranged to provide air curtain generation means 12 of the apparatus according to the invention, i.e. to provide fixed generation modules 20,20' (Figs. 3-6, 20-25) or movable generation modules 9 (Figs. 7- 12 and 16-19). Device 70 is suitable to provide still air spaces of relatively small size. Generation device 70 has a shape that is elongated along an axis 72, and comprises two fans, or a double plurality of fans 71 arranged to form two parallel stacks. The two fans, or the double plurality of fans 71 , can comprise fans that are provided with tangential delivery mouths and that are arranged to cooperatively form air curtains 13', 13". The fan, or each fan 71 can comprise a respective delivery mouth 77 that has a rectangular cross section, and which is arranged with the longer edge parallel to axis 72, in order to define an air blowing zone 75, to operatively form air curtains 13', 13".

In a preferred exemplary embodiment, device 70 comprises an orientation means, not shown, for orienting two fans 71 or the two stacks of fans 71 about respective rotation axes 74, for example independently from each other, in order to orient the air blowing zone consisting of mouths 77 and, accordingly, orient air curtains 13', 13".

Fig. 34 shows a device, according to the invention, in which main air curtain generation means 12 comprises a generation device similar to device 60,70 of Fig. 32,33, in which two sources 61' are provided arranged at a mutual distance B. Distance B and emission angle α',α" are selected in order to obtain a synergistic effect between two branches 15', 15" or 55', 55" of the resulting air flow consisting of a combination of air curtains 13', 13" and of wind 11. In particular, for a given value of emission angle α',α", distance B is set between a first value B' and a second value B" according to emission angle α',α". As shown by computational simulations and experimental tests, for values lower than the B', two branches 15', 15" or 55', 55" of the resulting air flow are likely to merge, which causes still air space 10 to implode, whereas for values higher than the B" wind 11 can pass through a space 67 between sources 61 ' and cause still air space 10 to disperse.

Figs. 35 and 36 show generation device 60 of Fig. 32 in a top plan view, where two exemplary modes are shown of arranging lateral air suction mouths 69 of source 61'. In Fig. 35, fans 61 are arranged such that suction mouths 69 are located behind and remotely from the middle line of air curtain generation means 60, such that the fans can be placed closer to each other. In the exemplary embodiment of Fig. 36, fans 61 are arranged such that suction mouths 69 are located proximate to the middle line of air curtain generation means 60, therefore they are arranged at a distance B that allows air suction and that can require a shield element 66 to be arranged behind air curtain generation means 60, i.e. among the latter and downwind space 10.

Fig. 37 shows the device of Fig. 34 as well as a flow distribution as created by main air curtain generation means 60, along with auxiliary air curtain generation means 29, in particular service conditions of auxiliary generation means 29 and of main air curtain generation means 60.

More in detail, by suitably selecting the following operation parameters:

- the ratio of the flowrate of each air curtain 13', 13" formed by main air curtain generation means 60 to the flowrate of auxiliary flow 31 formed by auxiliary air curtain generation means 29;

- the emission directions 14', 14" of air curtains 13',13" and direction of air auxiliary flows 31 ;

- the position and distribution of suction mouths 69 of main air curtain generation means 60 (Figs. 35,36),

in the regions between main air curtain generation means 60 and each auxiliary air curtain generation means 29 a zone 79 is formed of turbulent air circulation, which cooperates with branches 55', 55" of the resulting air flow to stabilize still air space 10. This result is anticipated by computational simulations and is confirmed by experimental tests. In other words, in such operating conditions the resulting flow of this turbulent circulation forms a resulting air flow 55', 55" that is particularly stable and strong, which opposes more effectively to wind 1 1 to create a wider and more stable still air space 10 than in other operating conditions.

Fig. 38 is a perspective view of an apparatus 8" similar to apparatus 8 of Fig. 18, in which main air curtain generation means 19 and auxiliary air curtain generation means 29 are arranged to form emission angles α',α" of about 90°, and extension angles γ of about zero, however air curtain generation means 19,29 can be arranged to form emission angles α',α" that are set between 40° and 90°, and extension angles γ of any values. For example, with fans 61 arranged as shown in Fig. 35, auxiliary air curtain generation means 29 can be arranged to form converging extension angles γ, in order to assist the formation of turbulence in the regions between the main air curtain generation means 19 and each auxiliary air curtain generation means 29, as shown in Fig. 37.

Fig. 39 shows a watercraft 90, which can be, for instance, a cruise ship, but also a ferry-boat, a yacht etc., on board of which an apparatus 8 is arranged according to an exemplary embodiment of the invention (Fig. 16), comprising a main and an auxiliary air curtain generation means 19,29, for creating a downwind space 10 in an outside zone 91 on watercraft 90. Apparatus 8 can be oriented in the zone 91 by displacing the air curtain generation means along a path, which can be defined by a guide 24.

In Fig. 39, the apparatus is shown in a configuration with the air curtain generation means towards the ship prow 93, which is suitable when watercraft 90 moves substantially in absence of wind, however, due to guide 24, apparatus 8 allows maintaining downwind space 10 also in case of sidewind, or in any case if the wind changes its direction, as it is the case, for instance, when the watercraft is at anchor.

Apparatus also 8 allows preventing the exhaust gas produced by a ship funnel 92 from entering zone 91 , for example as it occurs in case of headwind.

The foregoing description of some exemplary embodiments will so fully reveal the invention according to the conceptual point of view, such that others, by using the prior art, will be able to modify and/or adapt for various applications such exemplary embodiments without further research and without parting from the invention, and, accordingly, it is understood that such adaptations and modifications will have to be considered as equivalent to the exemplary embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is meant that the expressions or the terminology used herein is for the purpose of description and not of limitation.