The present invention relates generally to Prandtl probe which is employed to obtain a measurement of flow speed. More particularly, it related to an improved Prandtl probe having cooling means, due to which such a Prandtl probe can be used in hot and very hot environments for measuring fluid (e.g. gas, air, liquid) flow speed in industrial applications (e.g. in gas turbines, in chemical industry in chemical reactors, in cement production in cement kilns).

Prandtl (or Pitot-static) probe have been known and in common use for many years. In essence, the Prandtl probe is a device to measure static and total fluid pressure. Fluid flow velocity is determined by quantifying the difference between the total pressure (measured as with the pitot tube) and static pressure (measured as with the Prandtl tube). The difference between the static pressure and the total fluid pressure is a function of the velocity of the fluid flow.

The Prandtl probe 1 comprises at least two tubes 2, 3 (shown as a prior art on FIG 1): a total pressure tube 2 which is an L-shaped tube with a total pressure intake hole 21 on the short part of the L-shaped total pressure tube 2; The total pressure tube 2 is usually inserted in such way that the total pressure intake hole 21 of the L- shaped total pressure tube 2 is perpendicular to the fluid flow 4 and / or to a measurement plane , i.e. the total pressure intake hole 21 is directed into the fluid flow 4. a static pressure tube 3 is a tube which has static pressure intake hole 31 that are open in the way to be closed for the fluid flow 4. For example, such static pressure intake hole 31 can be in the tip of the static pressure tube 3 and is perpendicular to the fluid flow .

The total pressure tube 2 must be aligned directly with the fluid flow 4, with the total pressure intake hole 21 directly into the fluid flow 4. Otherwise, the accuracy of the total pressure measurement will be affected. Sometimes, the Prandtl probe 1 comprises further pressure tube 9 which has a further pressure intake hole 91 that are open under some angle towards the measuring plane. Based on the difference of the total pressure measured by the total pressure tube 2 and the further pressure measured by the further pressure tube 9, it is possible to define a slide slip angle an angle under which the fluid flow 4approaching the measuring plane.

The total pressure tube 2, the static pressure tube 3 and the further pressure tube 9 are connected to the measuring tool 5 that is configured for measuring pressure, fluid flow velocity, slide slip angle and etc.

The Prandtl probe 1 can be divided into two portions: an inner portion 6 that is placed into the fluid flow 4 for further measurement and an outer portion 7 that is located outside of the fluid flow 4. The measuring tool 5 is a part of the outer portion 7 and is located outside of the fluid flow 4.

Additionally, the Prandtl probe 1 may comprise a sealing 8 that is configured to prevent any fluid leaking through a window where the Prandtl probe 1 exits the fluid flow 4 and is located between the inner 6 and outer 7 portions of the Prandtl probe 1.

Usually, the Prandtl probe 1 is made in the form of a needle so as not to change the fluid flow 4 and therefore, to get as accurate measurements as possible. However, due to such shapes, it is possible to accurately measure angle of the fluid flow only in case it is up to 15°.

The Prandtl probe yields results accurate to within several percent when its inclination to the fluid flow is small, but significant error develops in the measurement of both static and total pressure if the fluid flow angle relative to axis that is perpendicular to a major Prandtl probe axis 10 is larger than about 10°. The pressure at the static pressure intake hole 31 is thus sensitive to the crossflow that occurs when mean fluid flow 4 incidence and/or velocity fluctuations are present. The main advantages of the Prandtl probe are high accuracy, robust and simple design, small influence on main fluid flow. Depending on operating conditions Prandtl probes are made from different materials. Metal alloys are usually used up to 1200C. For high temperature applications sintered ceramic materials like A1203 or Si3N4 are implemented (melting T about 2000C). But above 1800C in oxidizing medium ceramic materials becomes unstable and very crack-sensitive.

Additionally, these materials are expensive. Also, in case of impelling fluid flow (temperature of the fluid flow is changing) these materials also become crack-sensitive because of the changing temperature.

Conventional Prandtl probes are not capable to operate above high temperatures for a long period. On the other hand, global demand in efficient and cheap energy transformation requires continuous monitoring of process parameters in environments with extremely high temperatures.

Accordingly, the object of the present invention is to provide a cooled Prandtl probe assembly that allows to use it for measurements in extremely high temperatures. That is especially important for industrial applications, such as gas turbines .

The object of the present invention is achieved by a cooled Prandtl probe assembly as defined in claim 1. Advantageous embodiments of the present invention are provided in dependent claims. Features of claims 1 can be combined with features of dependent claims, and features of dependent claims can be combined together.

In an aspect of the present invention, a cooled Prandtl probe assembly is presented. The cooled Prandtl probe assembly comprises a Prandtl probe. The Prandtl probe comprises at least one total pressure tube with a total pressure intake hole on its end, wherein the at least one total pressure tube is adopted to provide a total pressure of the fluid flow to be measured, at least one static pressure tube with a static pressure intake hole on its end, wherein the at least one static pressure tube is adopted to provide a static pressure of the fluid flow to be measured, and a measuring tool connected to the at least one total pressure tube and the at least one static pressure tube.

The measuring tool measures at least total and static pressure of the fluid flow provided by the at least one total pressure tube and the at least one static pressure tube respectively.

The total pressure intake hole of the at least one total pressure tube and the static pressure intake hole of the at least one static pressure tube are situated in an inner part of the Prandtl probe that is to be placed in the fluid flow for further measurement. While the measuring tool is situated in an outer part of the Prandtl probe and kept outside of the fluid flow.

According to the present invention the cooled Prandtl probe assembly is characterized that the inner part of the Prandtl probe comprises a shell with a coolant fluid circulates inside it. The shell surrounds the at least one total pressure tube and the at least one static pressure tube. The coolant fluid circulating inside the shell cools down the surface of the shell and the at least one total pressure tube and the at least one static pressure tube that are located inside the shell.

However, the total pressure intake hole of the at least one total pressure tube and the static pressure intake hole of the static pressure tube are located on the shell in such way to be able to provide respective pressure of the fluid flow to the measuring tool.

The present invention is based on the insight that a coolant fluid that circulates inside the shell that covers the inner part of the Prandtl probe, i.e. covers the total pressure tube and the static pressure tube, cools down both the shell, including its surface, and respective pressure tubes that are situated inside the shell, while the intake holes of the total pressure tube and the static pressure tube are located on the surface of the shell, therefore they are open for the fluid flow, and, therefore, they are able to provide a total pressure and a static pressure of the fluid flow through the respective pressure tubes to the measuring tool for further measurement.

The coolant fluid cools down the surface of the shell and protects the respective tubes located inside the shell from overheating and further destruction, therefore allows to measure total and static pressure of the fluid flow and define further parameters of the fluid flow such as, for example, velocity of the fluid flow.

Such cooling allows using different, not very expensive, materials for the Prandtl probe and for the shell. Also, having such cooling of the shell and the Prandtl probe allows to operate the cooled Prandtl probe assembly for a long period in extreme conditions, compared to short usage of conventional probes .

Thus, the present invention is proposed to provide a cooled Prandtl probe assembly for measurements related to the fluid flow in hot environment.

Further embodiments of the present invention are subject of the further sub-claims and of the following description, referring to the drawings.

In a possible embodiment of the cooled Prandtl probe assembly, the shell is of elongated cylindrical shape with substantial elliptical cross section with a frontal vertex line and a back- vertex line that are opposite to each other and two shell wall sections that are between the frontal vertex line and the back- vertex line.

According to the present embodiment, the total pressure intake hole of the at least one total pressure tube is located on the frontal vertex line of the shell and the static pressure intake hole of the at least one static pressure tube is located on the back-vertex line of the shell. The shell can be of different shape. However, the shell of elongated cylindrical shape with substantial elliptical cross section allows to minimize the impact of the cooled Prandtl probe assembly on the fluid flow. Therefore, the accuracy of the measurement does not suffer.

Location of the total pressure intake hole on the frontal vertex line of the shell, that is usually used as a leading edge to face fluid flow running, allows to provide the total pressure of the fluid flow to the measuring tool.

Since the shell affects the fluid flow, the more accurate measurement of the static pressure of the fluid flow can be performed on the back-vertex line of the shell, since the fluid flow is not perturbed there. So, the static pressure intake hole of the at least one static pressure tube locates on the back-vertex line of the shell, that is a trailing edge and usually is opposite to the leading edge / the frontal vertex line .

In a possible embodiment of the cooled Prandtl probe assembly, the Prandtl probe further comprises at least one further pressure tube with a further pressure intake hole, wherein the at least one further total pressure intake hole is located on a shell wall section of the shell, wherein the at least one further pressure tube is adopted to measure a pressure of the fluid flow

This feature allows measuring a pressure of the fluid flow and, therefore, based on the difference of the total pressure measured by the at least one total pressure tube and the pressure measured by the at least one further pressure tube, to calculate an angle of fluid flow approaching the leading edge of the cooled Prandtl probe assembly. Depending on the location of such further pressure intake holes on the shell wall section of the shell, i.e. between the frontal vertex line and the back-vertex line, this feature allows defining a flow fluid angle up to 90° - it makes this assembly a wide ^¬ angled probe. In other possible embodiment of the cooled Prandtl probe assembly, the shell comprises an inner shell wall, an outer shell wall and a shell cavity that is formed by the inner shell wall and located inside the inner shell wall.

The at least one total pressure tube and the at least one static pressure tube are located inside the shell cavity, while some part of these tubes goes through the inner shell wall and the outer shell way in such way to have intake holes of the respective tubes to stay open for providing respective pressure of the fluid flow to the measuring tool.

A heat exchanger is located between the inner shell wall and the outer shell wall and is adopted for circulation of the coolant fluid inside it.

Such design of the shell allows the coolant fluid circulating inside the heat exchanger between the inner shell wall and the outer shell wall. Therefore, the shell is cooled down and the respective pressure tubes are cooled down. The shell cavity can be used for providing the coolant fluid to the heat exchanger .

In enhanced embodiment of the cooled Prandtl probe assembly, the inner shell wall comprises at least one inner opening along the frontal vertex line. The frontal vertex line is usually the leading edge while the cooled Prandtl assembly is located into the fluid flow for further measurements. Such at least one inner opening on the inner shell wall, that can be of different shape and different size, is adopted to provide the coolant fluid from the shell cavity into the heat exchanger.

Additionally, according to the present invention, the outer shell wall comprises at least one outer opening along the back- vertex line. The back-vertex line is the trailing edge while the cooled Prandtl assembly is located into the fluid flow for further measurements. Such at least one outer opening on the outer shell wall, that can be of different shape and different size, is adopted to release the coolant fluid out of the heat exchanger . Such design of the shell and the heat exchanger located between the inner shell wall and the outer shell wall allows providing effective cooling of the inner part of the Prandtl probe and the shell. The coolant fluid is provided to the shell cavity, then goes through the at least one inner opening in the inner shell wall to the heat exchanger and further goes to the fluid flow through the at least one outer opening in the outer shell wall. Therefore, an effective method of coolant fluid delivery to the heat exchanger and of coolant fluid removal from the heat exchanger is realized. Outburst of the warmed-up coolant fluid through the outer opening located on the back-vertex line, that is the trailing edge, does not affect the measurements of the total pressure made on the leading edge of the cooled Prandtl probe assembly.

Additionally, such method of the effusion of the coolant fluid through the outer openings to the fluid flow allows minimizing the size of the shell.

In enhanced embodiment of the cooled Prandtl probe assembly, wherein the heat exchanger is a porous matrix.

The porous matrix (or a porous material and / or material with a porous structure) is well-known. A porous structure is a regular or irregular/statistic material with an interconnected open pore system which allows permeation of a fluid through the structure. The porous matrix has very high heat transferring surface to volume ratio. Thermal conductivity is not so important but materials with higher thermal conductivity are preferred.

The heat from the fluid flow that warms up the outer shell wall is removed via volumetric heat transfer between porous matrix and coolant fluid flowing through the porous matrix. This is very effective way of cooling down the shell.

In other possible embodiment of the cooled Prandtl probe assembly, the porous matrix of the heat exchanger comprises at least one channel that is free of the porous matrix. Such channels in the porous matrix allows balancing the pressure of the coolant fluid within the heat exchanger. Additionally, in case the porous matrix is manufactured by additive manufacturing methods, such channels allow getting rid of dust out of the porous matrix.

In other enhanced embodiment of the cooled Prandtl probe assembly, the cooled Prandtl probe assembly fabricated by an additive manufacturing method. The additive manufacturing methods can be used to fabricate the cooled Prandtl probe assembly in whole, or partly, for example only inner part of the Prandtl probe together with the shell and the porous matrix .

Concerning fabricating the porous matrix by the additive manufacturing method, additive manufacturing lattice structures can be assumed as porous matrix, as well as microchannel systems made in CAD, as well as porous material generated by tuning the machine parameters (hatch distance, laser power/speed, layer thickness) which generates "imperfectly"· welded material with an open pore structure. This is an easy method to manufacture the porous matrix with required characteristics, including size.

In other enhanced embodiment of the cooled Prandtl probe assembly, the inner part of the Prandtl, that is surrounded by the shell, is separated from the outer part by a sealing.

Such sealing allows preventing fluid leakage when the inner part is inserted into the fluid flow for measurement.

For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in accompanying drawings. The invention is explained in more details below using exemplary embodiments which are specified in the schematic figures of the drawings, in which:

FIG. 1 schematically illustrates a Prandtl probe as a prior art;

FIG. 2 schematically illustrates a cooled Prandtl probe assembly in accordance with the present invention; FIG. 3 schematically illustrates an embodiment of the cooled Prandtl probe assembly in accordance with the present invention;

FIG. 4 schematically illustrates the cross-sectional view (A- A) of an embodiment of the cooled Prandtl probe assembly in accordance with the present invention;

FIG. 5 schematically illustrates the cross-sectional view (A-

A) of an enhanced embodiment of the cooled Prandtl probe assembly in accordance with the present invention;

FIG. 6 schematically illustrates the cross-sectional view (B-

B) of an embodiment of the cooled Prandtl probe assembly in accordance with the present invention;

FIG. 7 schematically illustrates cells of the acoustic structure that are honeycomb shaped in cross-section;

Various embodiments are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be noted that the illustrated embodiments are intended to explain, and not to limit the invention. It may be evident that such embodiments may be practiced without these specific details.

FIG 2 illustrates a cooled Prandtl probe assembly 100 that comprises a Prandtl probe 1. The Prandtl probe 1 comprises at least one total pressure tube 2 with a total pressure intake hole 21 on its end, at least one static pressure tube 3 with a static pressure intake hole 31 on its end, and a measuring tool 5.

The at least one total pressure tube 2 with the total pressure intake hole 21 on its end is adopted to provide a total pressure of the fluid flow 4 to be measured. The at least one static pressure tube 3 with the static pressure intake hole 31 on its end is adopted to provide a static pressure of the fluid flow 4 to be measured. As it is shown on FIG 3, the Prandtl probe lean have plurality of total pressure tubes 2 with respective total pressure intake holes 21 and / or plurality of static pressure tubes 3 with respective static pressure intake holes 31. Such tubes 2, 3 allows to measure respective pressure in different points of the fluid flow 4. Therefore, the profile of the respective pressure along the flow fluid can be measured. And, therefore, the profile of fluid flow velocity along the fluid flow can be calculated .

It is preferable, but not obligatory, to have the same number of the total pressure and static pressure tubes 2, 3.

The measuring tool 5 is connected to the at least one total pressure tube 2 and the at least one static pressure tube 3 to measure at least total and static pressure of the fluid flow 4 provided by the at least one total pressure tube 2 and the at least one static pressure tube 3 respectively.

The measuring tool 5 can comprise different types of sensors, that already well-known, to make measurement based on the respective pressures provided through the at least one total pressure tube 2 and the at least one static pressure tube 3. Such measuring tool 5 can comprise a controller that allows to calculate and output different parameters of the fluid flow 4 based on the respective pressures provided through the at least one total pressure tube 2 and the at least one static pressure tube 3. It can be velocity of the fluid flow 4. In some cases, the angle of the fluid flow 4 approaching the Prandtl probe 1 can be measured and outputted.

The Prandtl probe 1 comprises two parts: an inner part 6 that is usually situated into the fluid flow 4, and an outer part 7 that is usually situated outside the fluid flow 4. The measuring tool 5 are situated in the outer part 7 of the Prandtl probe 1 and kept outside of the fluid flow 4, while the total pressure intake hole 21 of the at least one total pressure tube 2 and the static pressure intake hole 31 of the at least one static pressure tube 3 are situated in the inner part 6 of the Prandtl probe 1 that is to be placed in the fluid flow 4 for further measurement. According to the present invention, the cooled Prandtl probe assembly 100 comprises the Prandtl probe 1 and a shell 200 that surrounds the inner part 6 of the Prandtl probe 1. The shell 200 is constructed in such way that it surrounds the at least one total pressure tube 2 and the at least one static pressure tube 3, and the total pressure intake hole 21 of the at least one total pressure tube 2 and the static pressure intake hole 31 of the static pressure tube 3 are located on the shell 200 in such way to be able to provide respective pressure of the fluid flow 4 to the measuring tool 5. In other words, the at least one total pressure tube 2 and the at least one static pressure tube 3 that are usually placed in the fluid flow 4 are situated in the shell 200, however, the total pressure intake hole 21 and the static pressure intake hole 31 of the respective tubes 2, 3 are integrated into the shell 200 in such way to be open for the fluid flow 4 and to be able to provide respective pressure to the measuring tool 5.

A coolant fluid 300 circulates inside the shell 200 and cools down the surface of the shell 200 and the at least one total pressure tube 2 and the at least one static pressure tube 3 that are located inside the shell 200. Therefore, the inner part 6 of the Prandtl probe 1 is not suffer from the high temperatures of the fluid flow 4.

The shell 200 can be of different size and different shape. However, preferably, the shell 200 should have such shape that does not change and affect much the fluid flow 4. Otherwise, the accuracy of the measurements will suffer. According to the present invention, the shell 200 is of elongated cylindrical shape having a major shell axis 210 generally perpendicular to the plane of measurement, i.e. most often perpendicular to the fluid flow 4. Such shape of the shell 200 allows to minimize the interference of the cooled Prandtl probe assembly 100 on the fluid flow 4 and, therefore, the measurements will be accurate. In fact, the more streamlined shape of the shell 200, the better. The shell 200 preferably has a substantial elliptical cross section (as shown on FIG 4) with a frontal vertex line 201 and a back-vertex line 202 that are opposite to each other and two shell wall sections 203 that are between the frontal vertex line 201 and the back-vertex line 202.

Moreover, the total pressure intake hole 21 of the at least one total pressure tube 2 is located on the frontal vertex line 201 of the shell 200 and the static pressure intake hole 31 of the at least one static pressure tube 3 is located on the back-vertex line 202 of the shell 200.

Additionally to the total pressure tubes 2 and the static pressure tubes 3, the Prandtl probe 1 further can comprise at least one further pressure tube 9 with a further pressure intake hole 91. Such further total pressure intake hole 91 of the al least one further pressure tubes 9 is located on a side wall section 203 of the shell 200, between the frontal vertex line 201 and the back-vertex line 202.

The at least one further pressure tube 9 is adopted to measure a pressure of the fluid flow 4. There can be a plurality of the further pressure tubes 9 adopted to measure a pressure of the fluid flow 4 in the location point of the respective further pressure intake hole 91. It is preferably to make at least two further pressure tubes 9 with further pressure intake holes that are located on both shell sections.

The coolant fluid 300 circulating inside the shell 200 cools down the shell 200 itself and all tubes 2, 3, 9 located inside the shell 200. Such coolant fluid 300 can be supplied to the shell 200 by different way. For example, there can be additional a coolant tube 301 that is connected with a source 302 of the coolant fluid outside on the flow fluid 4. Coolant fluid 300 can circulate in the shell 200 in different ways. The removal of the coolant fluid 300 from the shell 200 also can be done by separate tubes (not shown on FIG) to go outside of the fluid flow 4. According to the present invention as it is shown on FIG 5, the cooled Prandtl probe assembly 100 comprises a heat exchanger 400 that is located between an inner shell wall 204 and an outer shell wall 205.

The tubes - the at least one total pressure tube 2 and the at least one static pressure tube 3, and the at least one further pressure tube 9, if any - are situated inside a shell cavity 206 formed by the inner shell wall 204 and located within the inner shell wall 204. However, the parts of the tubes 2, 3, and 9, if any, are integrated into the shell 200, i.e. are integrated into the inner shell wall 204, the heat exchanger 400 and the outer shell wall 205 in such way to have respective intake holes 21, 31, 91 open for the fluid flow 4 to provide respective pressure to the measuring tool 5.

The shell cavity 206 can be used for providing the coolant fluid 300 to the heat exchanger 400. The coolant fluid 300 can be supplied to the heat exchanger 400 by different ways and warmed-up coolant fluid 300 can be removed from the heat exchanger 400 in different ways. However, according to the other embodiment of the present invention, the coolant fluid 300 is supplied to from the shell cavity 206 to the heat exchanger 400 through at least one inner opening 214 that is located on the frontal vertex line 201 of the inner shell wall 204.

The at least one inner opening 214 can be of different shape and of different size. There can be plurality of such inner openings 214, for example, plurality of orifices, along the frontal vertex line 201. The inner opening 214 should be of such size and such shape to provide enough coolant fluid 300 to the heat exchanger 400. Preferably, it should be one inner opening 214, but along entire length of the frontal vertex line 201 of the shell 200.

Having one inner opening 214 but entire length of the frontal vertex line 201 of the shell 200 allows loading the coolant fluid 300 evenly throughout all length of the heat exchanger 400 along the frontal vertex line 201 of the shell 200. It is preferable to remove the warmed coolant fluid 300 by using internal piping outside the inner part 6 of the Prandtl probe 1 and outside of the shell 200 - in other words - to create a closed-loop cooling scheme. For this case a low- pressure coolant fluid even for high-pressure applications can be used. Moreover, for liquid cooling it is possible to create completely closed cooling system with refrigerator somewhere outside the flow fluid.

However, such close-loop cooling scheme requires enough space inside the inner part of the Prandtl probe and the shell 200. However, the size of the shell 200 can be limited by the window through which the cooled Prandtl probe assembly should be introduced to the fluid flow 4. Additionally, the bigger the shell 200 is, the more negative effect / influence on the fluid flow 4 it makes.

Therefore, in accordance with an enhanced embodiment of the present invention, the removal of already warmed-up coolant fluid 300 can be executed through at least one outer opening 215 that is located on the back-vertex line 202 of the outer shell wall 205 of the shell 200.

The at least one outer opening 215 can be of different shape and of different size. There can be plurality of such outer openings 215 (for example, plurality of orifices) along the back-vertex line 202. The outer opening 215 should be of such size and such shape to effectively remove already warmed-up coolant fluid 300 out of the shell 200 to the fluid flow 4. Preferably, it should be one outer opening 215, but along entire length of the back-vertex line 202 of the shell 200.

Having one outer opening 215 but entire length of the back- vertex line 202 of the shell 200 allows removing the coolant fluid 300 evenly throughout all length of the heat exchanger 400 along the back-vertex line 202.

However, the pressure of the coolant fluid 300 supplied to the shell cavity 206 and further to the heat exchanger 400 should be high enough to effuse the coolant fluid 300 to the main fluid flow 4 out of the heat exchanger 400. Hot coolant fluid 300 has lower density and lower pressure due to losses in the heat exchanger, thus much larger pipe diameters to supply it back outside of the inner part 6 of the Prandtl probe 1 is needed. So, it is much more convenient simply to effuse the coolant fluid 300 to the main fluid flow 4 decreasing dimensions and complexity of the shell 200 and of the cooled Prandtl probe assembly 100 in whole.

The heat exchanger 400 can be of different types and can be manufactured in different ways. For example, it can be microchannel heat exchanger, when the heat exchanger 204 comprises of plurality small and thin microchannels within which flows the coolant fluid 300. Another option is a very ribbed / finned heat exchanger, when there are the shell walls 204, 205 of the shell 200 - between the outer shell wall 205 and the inner shell wall 204 - high number of ribs or fins that form large surface for heat transfer. Therefore, the coolant fluid 300 goes between the shell walls 204, 205 and takes off the heat from these ribs / fins.

In other embodiment of the present invention, the heat exchanger 400 is a porous matrix.

As it was mentioned above, the porous matrix has a very large heat transfer area and is easy in manufacturing, especially using additive manufacturing methods. The porous matrix 400 is designed to offer minimum pressure drop for the coolant fluid 300 passing the heat exchanger 400.

The heat from the fluid flow 4 that warms up the shell 200 is removed via volumetric heat transfer between porous matrix 400 and the coolant fluid 300 flowing through the porous matrix 400. This is very effective way of cooling down the shell 200.

The porous matrix 400 can be of different parameters (e.g. pore diameters) that should be defined by experts. Porosity variation along the porous matrix 400 can be used to control heat transfer between the shell walls 204, 205 and the coolant fluid 300.

Additionally, the porous matrix of the heat exchanger 400 may comprise at least one channel 401 free of the porous matrix. The cooled Prandtl probe assembly 100 can have plurality of such channels 401 that are free of the porous matrix. Such channels 401 in the porous matrix of the heat exchanger 400 allows balancing the pressure of the coolant fluid 300 within the heat exchanger 400. Hollow volumes of the channels 401 in the porous matrix of the heat exchanger 400 reduce an overall coolant flow resistance that leads increasing of the coolant flow rate at given pressure drop. The coolant fluid 300 getting into such channel 401 is evenly distributed over it and then evenly gets into the next section of the porous matrix of the heat exchanger 400. Therefore, there is no overheating areas in the heat exchanger 400.

The size, the shape, the location and the number of such channels 401 should be defined by experts. Preferably, there should be at least two such channels 401, at least one per the shell wall section 203.

Also, preferably, such channels 401 are mostly oriented in parallel with the major shell axis 210 of the shell 200.

Additionally, in case the porous matrix 400 is manufactured by additive manufacturing methods, such channels 401 allow getting rid of dust out of the porous matrix 400.

In enhanced embodiment of the present invention, the shell 200 with the porous matrix of the heat exchanger 400 is fabricated by an additive manufacturing method from appropriate temperature resistant alloys to prevent oxidation and cracking at large temperature gradients. This is well known method.

The complete part of the cooled Prandtl probe assembly 100 is made by additive manufacturing / generative production, e.g. by laser metal powder bed fusion technology. The cooled Prandtl probe assembly 100 may consist of the same substance, e.g. same metal alloy or same metal-ceramic composite material, as one monolithic component.

However, such additive manufacturing allows to produce the porous matrix 400 with required characteristics and of required sizes and shape. The complete part is made by additive manufacturing / generative production, e.g. by laser metal powder bed fusion technology. The body consists of the same substance, e.g. same metal alloy or same metal-ceramic composite material, as one monolithic component.

As it was mentioned above some part of the cooled Prandtl probe assembly 100 is placed in the flow fluid 4 with high temperature, while another part of the cooled Prandtl probe assembly 100 is located outside of the flow fluid 4, therefore there is a task to prevent leakage of the flow fluid 4 through a window (not shown on FIG, as it is covered with the sealing 8) the inner part 6 of the Prandtl probe 1 surrounded with the shell 200 is inserted into the flow fluid 4.

So, according to the present invention, the cooled Prandtl probe assembly 100 comprises a sealing 8 that has a shape of the window the shell 200 with the inner part 101 of the Prandtl probe 1 is inserted into the flow fluid 4. Such sealing 8 prevents fluid leakage when the inner part 6 is inserted into the fluid flow 4 for measurement.

Usually, the sealing 8 has the shape of a window that is used to introduce the cooled Prandtl probe assembly into the fluid flow 4 to take measurements. Further the sealing 4 and the outer part 7 of the cooled Prandtl probe assembly 100 can be cooled down by using different cooling systems (e.g. water cooling) .

The thicknesses of the shell walls 204, 205 - the inner shell wall 204 and the outer shell wall 205 - and the thicknesses of the heat exchanger 400 should be defined by experts based on the cooling reguirements and surrounding parameters in the application .

The cooled Prandtl probe assembly 100 works the following.

The work principles of the Prandtl probe 1 are well known. So, it will not be described here in details.

The cooled Prandtl probe assemble 100, in particular the inner part 6 of the Prandtl probe 1 surrounded with the shell 200 should be located into the fluid flow 4 that flows inside a fluid flow channel 500.

It is preferably to locate the cooled Prandtl probe assembly 100 perpendicular to the fluid flow 4, i.e. in such way that the major shell axis 210 of the cooled Prandtl probe assembly 100 is perpendicular to the fluid flow 4. However, in some cases, a direction of the fluid flow 4 is not well known, or constructively it is not possible to locate the cooled Prandtl probe assembly 100 perpendicular to the fluid flow 4. In such cases, the cooled Prandtl probe assembly 100 should be located in such way that the flow fluid 4 approaches the frontal vertex line 201 of the shell 200 first, i.e. the frontal vertex line 201 of the shell 200 should be a leading edge of the shell 200, while the back-vertex line 202 of the shell 200 should be a trailing edge of the shell 200.

In case of embodiment of the cooled Prandtl probe assembly 100 in which the Prandtl probe 1 comprises one or more further pressure tubes 9 with a further pressure intake hole 91, the cooled Prandtl probe assembly 100 allows measuring an angle the flow fluid 4 approaching the leading edge 201 of the shell 200. It can be done by measuring the pressure of the fluid flow 4 in location on the shell wall sections 203 of the shell 200. Preliminarily, the cool Prandtl probe 100 with particular locations of the further total pressure intake hole 91 on the shell wall sections 203 of the shell 200 should be calibrated depending on angle of the fluid flow 4 towards the leading edge / the frontal vertex line 201 of the shell 200.

Due to the elongated cylindrical with substantial elliptical cross section shape of the shell 200, the cooled Prandtl probe assembly 100 allows measuring wide angles - up to 90° of the fluid flow 4 towards the leading edge / the frontal vertex line 201 of the shell 200.

Since the fluid flow 4 is of extremely high temperature it is preferably to avoid any leakages of the fluid flow 4 from the area where it flows through a window through which the cooled Prandtl probe assembly 100 is introduced. Also, any leakages can negatively affect the performance of the equipment (e.g. a gas turbine) in which such fluid flow 4 is used. Therefore, it is essential for the cooled Prandtl probe assembly 100 to have a special sealing 8 that is designed in such way to prevent fluid leakage when the cooled Prandtl probe assembly 100 is inserted into the fluid flow 4 for measurements. Also, all tubes 2, 3, 9 go through this sealing 8 to the measuring tool 5. Moreover, additional one or more tubes / channels, e.g. channels 301 for delivering the coolant fluid 300 and / or channels for removal the coolant fluid 300 from the shell 200, can go through the sealing 8 to the shell 200.

The coolant fluid 300 provided into the shell 200 cools down the respective pressure tubes 2, 3, 9 that are located inside the shell 200 and the shell 200 itself.

A wide variety of coolant as e.g. cold air, hot compressed air, nitrogen, helium, argon, water, demineralized water, alcohols, hydrocarbons, cooling oils, silicone oils, can be used as a coolant fluid 300.

In case of embodiment the cooled Prandtl probe assembly 100, the coolant fluid 300 is provided to the shell cavity 206, further goes to the heat exchanger 400 that is located between the inner shell wall 204 and the outer shell wall 205. In general, the cooling fluid 300 flows between two thin, impermeable solid walls - the outer shell wall 205 and the inner shell well 204 through the heat exchanger 400. As shown on FIG 6, the coolant fluid 300 enters the heat exchanger 400 through the inner opening 214 from the shell cavity 206. Further, the coolant fluid 300 goes through the heat exchanger 400. Since the coolant fluid 300 enters the heat exchanger 400 on the frontal vertex line 201, the coolant fluid 300 is separated and goes through the heat exchanger 400 in both shell wall sections 203 from the frontal vertex line 201 of the shell 200 towards the back-vertex line 202 of the shell 200. Going through the heat exchanger 400, the coolant fluid 300 is warming up taking the heat from the heat exchanger 400 and, therefore, cooling down the shell 200, and everything that is located inside the shell 200, in particular respective tubes 2, 3, 9 that provide pressure to the measuring tool 5 for further measurements. In other words, the heat from the fluid flow 4 is supplied to the outer shell wall 205 and removed via volumetric heat transfer between the heat exchanger 400 and the coolant fluid 300 that passing through it.

In enhanced embodiment of the cooled Prandtl probe assembly 100 in which the heat exchanger 400 is a porous matrix, the heat exchanger 400 additionally has one or more channels 401 that are free of the porous matrix. Such channels 401 are designed to equalize the pressure of the coolant fluid 300 inside the heat exchanger 401. In case of uneven heating of the shell 200 and the heat exchanger 401, respectively, the coolant fluid 300 may flow inside the heat exchanger 401 with different velocity in different areas of the heat exchanger 400, and therefore, the coolant fluid 300 may be unevenly distributed inside the heat exchanger 400.

The channels 401 separates the heat exchanger 400 on several heat exchanger sections 402, 403. The coolant fluid 300 inside the channel 401 is quickly got evenly distributed. Therefore, the coolant fluid 300 enters next heat exchanger section 403 along its length. Therefore, the cooling of the heat exchanger 400 is even.

Also, in case of porous matrix 400 fabricated by additive manufacturing method, such channels 401 help removing a dust from the porous matrix.

Finally, the already warmed up coolant fluid 300 gets effused to the trailing edge / the back-vertex line 202 of the outer shell wall 205 through the outer opening 215. The warmed-up coolant fluid 300 joints the fluid flow 4 already on the trailing edge 202 of the shell 200 and therefore, does not affect the measurements of the total pressure.

The cooled Prandtl probe assembly 100 comprise one or more total pressure tubes 2 with a total pressure intake hole 21 and one or more static pressure tubes 3 with a static pressure intake hole 31.

It should be noted that in case the cooled Prandtl probe assembly 100 comprises several total pressure tubes 2 and therefore there are respective number of total pressure intake holes 21 on the shell 200, the cooled Prandtl probe assembly 100 is able to measure total pressure of the fluid flow 4 in the points where the total pressure intake holes 21 are located, therefore, it is possible to receive a profile of total pressure along the major axis of the shell 200. Have such measurements of total pressure, it is possible to receive a profile of velocity of fluid flow along the major axis of the shell 200.

Proposed invention allows to decrease temperature of the shell 200 and the inner part 6 of the Prandtl probe 1 in high temperature environment. Also, it allows to use nickel-based alloys that immune to ablation in the high temperature fluid flows and velocity flows instead of ceramics which have carrying away effect in such flows during operation time. While the present invention has been described in detail with the reference to certain embodiments, it should be appreciated that the present invention is not limited to those precise embodiments. Rather, in view of the present disclosure which describes exemplary modes for practicing the invention, many modifications and variations would present themselves to those skilled in the art without departing from the scope and spirit of this invention. The scope of the invention is, therefore, indicated by the following claims rather than by the foregoing description. All changes, modifications, and variations coming within the meaning and range of equivalency of the claims are to be considered within their scope.

Reference numerals

1 - Prandtl probe

2 - total pressure tube

3 - static pressure tube

4 - fluid flow

5 - measuring tool

6 - inner part of the Prandtl probe

7 - outer part of the Prandtl probe

8 - sealing

9 - further pressure tube

10 - major Prandtl probe axis 21 - total pressure intake hole 31 - static pressure intake hole 91 - further pressure intake hole 100 - cooled Prandtl probe assembly

200 - shell

201 - frontal vertex line, leading edge

202 - back-vertex line, trailing edge

203 - shell wall section

204 - inner shell wall

205 - outer shell wall

206 - shell cavity 210 - major shell axis

214 - inner opening

215 - outer opening

300 - coolant fluid

301 - coolant tube

302 - source of coolant fluid

400 - heat exchanger

401 - channel

500 - fluid flow channel