Branch of Science Associated with the Invention

The present disclosure relates to a new innovative design of a propeller for both substantially compressible and incompressible fluids. More particularly, the invention relates to propellers for use in wind turbines, aircraft engines, drones, cooling fans and marine based applications.

Background of related art or science

A propeller is a device to convert torque into thrust, thereby converting rotational motion into linear motion by accelerating fluid axially. For a propeller to generate the maximum amount of thrust with the least amount of shaft power input, a combination of high blade pitch and low rotational speed is of advantage.

While the aerodynamics of a standard propeller can be designed by following the standard design procedures for such a propeller; this will always result in a standard propeller with standard efficiency and standard drag characteristics.

The maximum pitch that can be applied to the propeller is in practice limited by the velocity of the fluid it is operated in. If the incoming fluid velocity is low or zero, the propeller blade will experience stall at too high pitch angles and will not move any fluid at all. A fan or static thruster which operates in zero velocity conditions is therefore limited in how efficient it can operate due to pitch angle constrains.

Despite this the efficiency of propellers in use is not high with cavitation and aeration being major problems in all types of propellers with the balance between the design factors of propeller size, rotational speed, power input, drag, thrust and efficiency. Among attempts to resolve such problems is of US patent 10,400,785 B2 which utilises blades of hyperbola shape at different radial distances from the blade root; yet unable to achieve the required efficiency as expected.

To some extent, above-mentioned propeller has failed to provide a solution to the problem of achieving increased efficiency from a propeller while achieving reduced cavitation and aeration. Therefore a need exists for a solution to the problem of providing such increased efficiency.

Therefore, using the background of our previous patent US 10,400,785 B2, switching from hyperbola equation to a polynomial expression allows us to cover distinctive designs of the blade of the propeller aiming to target various existing applications and ultimate goal is to improve efficiency.

The object of this invention is to provide a propeller that can be operated at high blade variable pitch angles at zero fluid velocity inflow conditions without stalling, delivering equivalent thrust at significantly reduced power input levels when compared to conventional type propellers, or at least provides the public with a useful alternative to conventional propellers.

Description and Purpose of the Invention

In a first aspect the invention comprises a propeller blade with a surface geometry defined by the projection of surface lines from an origin to a three dimensional spiral, wherein the spiral is formed by the projection of a two dimensional spiral onto a surface of revolution defined by generic functions of a polynomial.

Preferably the two dimensional spiral is a Fibonacci spiral.

Displacement from the origin to the final point of Fibonacci equals to the radius of the cone shaped from the polynomial equations.

In general, the polynomial equation could be a monomial, binomial, trinomial and quadratic polynomial wherein the displacement from the origin to the final point of Fibonacci equals to a radius of the cone shaped from any of the above-mentioned polynomial equation.

The surface and design can be applied with all sorts of turbines and propellers.

Preferably the leading and trailing portions of the blade are symmetrical for various applications including wind turbines, drone, cooling fans, aircrafts and marine applications or asymmetric for marine applications.

For increased performance in one direction the leading portion is smaller than the trailing portion.

The alignment of the cone shaped from polynomial equation against the Fibonacci spiral can be at any angles.

Preferably the thickness of the blade is uniform.

In a further aspect the invention comprises a propeller with a plurality of propeller blades.

The final projection of the surface is retrieved from the intercepted points between the Fibonacci spiral and the cone shaped from polynomial equations.

Surface of the blade formed using polynomial expression against spiral can be convex and concave at the same time.

It should be noted that any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below as appropriate.

These and other features of as well as advantages which characterise the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.

The design of a propeller derived from fundamentals of trigonometry and is something which can be altered using reverse engineering calculation with the help of supercomputers and development or conceiving ideas by such means should be considered as a violation of copyright for this patent.

Full Disclosure of Invention

The following detailed description of the invention refers to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration.

The invention describes propellers comprising logarithmically scaled blades where their surface contours are derived from the flow contours inherent in a natural vortex. It has been found that propellers constructed in this manner can be operated at high blade pitch angles at zero fluid velocity inflow conditions without stalling, delivering equivalent thrust at significantly reduced power input levels when compared to conventional type propellers.

Fluid flow inside of a vortex funnel occurs in a self-organised manner in accordance with clearly defined geometric parameters. In a vortex, the fluid will flow without turbulence and with greater velocity. The propeller blades described in the invention, have surface contours derived from the vortex flow-line geometry resulting in propellers that resist the formation of surface turbulence and will engender an even and coherent fluid flow across their surfaces. As a result, the propellers may be operated at steep pitch angles in low fluid inflow velocity conditions, without stalling. By operating at a lower rotational speed at the same air volume delivery rate, significantly less shaft power is consumed and as the blade tip speed is reduced, noise is also reduced. Alternatively a fixed amount of power can be used to deliver a higher volume of air when compared with conventional propellers.

The underlying geometric shape of a vortex is an equiangular logarithmicspiral also known as golden spiral or Fibonacci spiral as is often found in natural objects ranging from sea shells to spiral galaxies. When viewed three dimensionally, the fluid flow in a vortex can be drawn as a projection of a golden spiral onto a surface of revolution of a polynomial function where the variable can occur in the equation more than one time with different degree of the exponent and the displacement from the origin to the final point of Fibonacci equals to a radius of the cone shaped from polynomial equation covering both symmetric and asymmetric aspects.

Figure 1 shows the basic geometrical components used to define the surface of a propeller blade according to the invention. A quadratic polynomial shows the base formed as the parabola is rotated through 360° to form a surface of revolution. A golden spiral around the origin of the quadratic parabola is projected onto the surface of revolution to form a 3d spiral corresponding to the fluid flow in a vortex. Figure 1 is shown with a grid to aid visualisation. A further representation of the geometry is shown without a grid in Figure 2.

A first half surface geometry of a propeller blade is shown by the mesh in Figure 3 which is formed from lines starting at the origin (of the spiral and the quadratic polynomial) and terminating on the 3d spiral. In Figure 4 the surface is copied and rotated to make a second surface. Together the surfaces create a continuous surface with diverging and converging flow contours.

A first blade profile is shown in Figure 5. The blade profile is projected onto the surface to form a first propeller blade.

The symmetric profile across the XY horizontal cross section of the first propeller blades provides equal performance in both directions of rotation of the propeller.

The blade profile may be varied for either aesthetic or performance considerations and also the blade may or may not extend to the hub of the propeller. Such variations have shown to have minimal impact on performance.

A second symmetric blade profile is shown in Figure 6. The blade profile is projected onto the surface to form a second propeller blade; which in combination with two further blades forms a second propeller as shown in Figure 7 which is primarily being designed for wind turbines.

A second complete propeller based on blade profile is shown in Figure 8 and comprises two blades evenly spaced around a hub and designed specifically for drone applications.

A third complete propeller based on symmetric profile is shown in Figure 9 and comprises two blades evenly spaced around a hub and designed specifically for aircraft application.

Fourth complete propeller based on asymmetric blade profile is shown in Figure 10 and comprises four blades evenly spaced around a hub and designed specifically for marine applications.

Another complete propeller based on symmetric blade profile is shown in Figure 11 and comprises four blades evenly spaced around a hub and designed specifically for marine applications.

Another complete propeller based on symmetric blade profile is shown in Figure 12 and comprises four blades evenly spaced around a hub and designed specifically for cooling fan application. In an alternative embodiment of the invention an asymmetric projection onto the surface of Figure 4 is used to produce an asymmetric blade profile as shown in Figure 10. Such a propeller will operate in a first direction (with the narrower part of the profile leading) with greater efficiency than the symmetric propellers available commercially.

The asymmetric profile across the XY horizontal cross section of the first propeller blades provides equal performance in both directions of rotation of the propeller.

The propeller of Figure 8 has been shown in wind tunnel testing to have an even and consistent airspeed across the entire length of the blade which leads to its efficiency. In contrast a fan of conventional profile has the highest airspeed at roughly 2/3 of its diameter reducing to zero towards the centre and the tip.

A working prototype of the invention was produced and compared with a conventional ceiling fan with a diameter of 1. 5 m . At a shaft speed of 730 rpm the standard fan delivered 700 m3 /minute of air at 23.45 N torque. In comparison to hyperbolic design, this propeller able to have 52 % increase in efficiency. Further tests and simulations of different blade diameters and speeds have shown comparable improvements. It has also been demonstrated that the pitch is optimal at all speeds but it performs exceptional even at variable pitch ratios. This is unlike conventional propellers which have an optimal pitch that is speed dependent. Airflow is adjusted by varying the speed of the propeller alone, which is relatively simple to implement. By being able to produce the same airflow at a lower speed the propellers are much quitter in operation, with tests showing a reduction in noise.

A further asymmetric propeller made in accordance with the invention is shown as in Figure 10. The profile of this propeller does not extend all the way to the hub. This propeller has been extensively modelled and compared to one of the better performing examples of prior art propellers on the market.

The propeller is also unlike many traditional propellers in that it does not need to act as an aerofoil and can thus be made a uniform thickness. This is advantageous as it greatly simplifies construction of the propellers as they can be stamped from a metal sheet. The propellers can also be extremely thin thus reducing drag.

In a further embodiment of the invention, not shown, the leading and trailing portions of the propeller are made in symmetric and asymmetric forms. A propeller with a steeper leading profile has been found to offer even greater performance advantages.

The present invention provides clear understanding to the reader that a propeller that can be operated at high and variableblade pitch angles at zero fluid velocity inflow conditions without stalling, delivering equivalent thrust at significantly reduced power input levels when compared to conventional type propellers.

Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field.

In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Figure 1 shows a spiral projected onto a surface of revolution of a polynomial used to determine the geometry of a propeller blade of the present invention. A mesh is included to aid 3d visualisation.

Figure 2 shows Figure 1 without a mesh.

Figure 3 shows a three dimensional surface constructed from the projection of Figure 2 representing half the surface geometry of a propeller blade.

Figure 4 shows the surface of Figure 3 copied and rotated to produce a complete surface geometry of a propeller blade.

Figure 5 shows a first propeller blade profile being projected onto the surface of Figure 4 to form a first propeller blade. Figure 6 shows a second propeller blade profile being projected onto the surface of Figure 4 to form a second propeller blade.

Figure 7 shows a first propeller formed by three blades of Figure 5 displaced about a central hub for wind turbine application.

Figure 8 shows a second propeller formed by two blades of Figure 6displaced about a central hub for drone application.

Figure 9 shows a second propeller formed by two blades of Figure 6 displaced about a central hub for aircraft application.

Figure 10 shows a fourth propeller formed with an asymmetric profile for marine application.

Figure 11 shows a fourth propeller formed with an symmetric profile for marine application.

Figure 12 shows a fourth propeller formed with an symmetric profile for cooling fan application with the prior art propeller of Figure 13.

Figure 13 shows a prior art propeller used for comparison purposes

Best Invention Method

As stated in the Full Disclosure of Invention.