AU2018101230B4

AU2018101230B4 - Aerodynamic Regulation of Airscrew-, Fan- and Wind Turbine Blades with Bores and/or Cutting and/or Notching

Info

Publication number: AU2018101230B4
Application number: AU2018101230A
Authority: AU
Inventors: Norbert CÍRUS; Róbert CÍRUS; Attila NYÍRI
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-08-24
Filing date: 2018-08-24
Publication date: 2019-05-02
Anticipated expiration: 2026-08-24
Also published as: AU2018101230A4

Abstract

Page 1 of 1 Extract Title: Aerodynamic Regulation of Airscrew-, Fan- and Wind Turbine Blades with Bores and/or Cutting and/or Notching Axial airplane airscrew-, fan-, and wind turbine blade of low loading is characterised by the fact that the aspect ratio of the airscrew-, fan- and wind turbine blades is low; near the wide blade ends, but in an appropriate distance an aperture of appropriate length and width - almost parallel to the side of the blade end - is formed, which connects the surfaces of lower and higher pressure. When being operated, the air flowing through this aperture eliminates the turbulence formed at the end of the blades. With regards to diameter, the choice of the distribution of strings on the airscrew blade (its blade width) caused problems in case of adapting a huge performance, as well as there was a need to form wide blade ends. The losses resulting from the circular flow of the blade ends were, however, increased dramatically. In case of adapting wide blade ends, the invention uses the phenomenon known from physics as interference, more precisely whirl interference to reduce or eliminate the loss of potential resulting from the circular flow of the blade ends tips on the airscrew. A whirl of contrary direction and of equal angular momentum (or impulse momentum) is induced at the ends of the airscrew blades, which by this eliminates or significantly reduces the whirls appearing at the end of wide blades and causing losses. As a result of this, a tractive force evolves on the airscrews and the range of action of the aircraft as well as the time spent flying can be increased. Its application is also recommended on wind turbine rotor blades. If applied, it reduces the resonant vibrations occurring on the blades and the turbines, and thus extending their lifetime significantly. Using aerodynamic braking the forming of the pivoting tip is more effective and less vibrating. The blade edges are working as slotted flaps.

Description

2018101230 05 Apr 2019

Aerodynamic Regulation of Airscrew-, Fan- and Wind Turbine Blades with Bores and/or Cutting and/or Notching [0001] The pressure distribution of airscrew-, fan-, and wind turbine blades, and by this the determination of flow characteristics are solved by means of linking the areas of different pressure (low and high) on the blades with bores and/or cutting and/or notching.

[0002] The original pressure characteristics are changed due to the flow resulting from the pressure difference in the bores, cuts or notches. These changes are of such nature that on the blades (from a physical and technical point of view) the emergence of unfavourable turbulences is reduced or eliminated. The solution can be used on tools of any desired size.

[0003] One way to realize this is when close to the end of the blade, but on a point which is in an appropriate distance from it, a cut of appropriate width and almost parallel to the end of the blade is shaped. The air flowing through this aperture eliminates the air turbulence which would otherwise occur on the end of the blades.

[0004] The elaborator of the most modem theory on airscrews so far is Sydney Goldstein, who took into consideration the circulation on the airscrew blades serving the ascensional force, as well as - by assuming a constant circulation - the effect of whirling strings of spiral shape leaving the end tips of the airscrew blades. {Goldstein, Sydney. (1929). On the Vortex Theory of Screw Propeller. Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences. 123. 440-465. 10.1098/rspa.l929.0078.} [0005] Goldstein solved the task of potential theory defining the velocity distribution by a lightly loaded airscrew of two, three and four blades. From a practical point of view, the result of the theory appears in a corrective factor, which mainly phrases the loss of potential resulting from the circular flow of the blade end tips on the airscrew.

[0006] With regards to diameter, the choice of the distribution of strings on the airscrew blade (its blade width) caused problems in case of adapting a huge performance, as well as there was a need to form wide blade ends. The losses resulting from the circular flow of the blade ends were, however, increased dramatically.

[0007] In case of adapting wide blade ends, the invention uses the phenomenon known from physics as interference, more precisely whirl interference to reduce or eliminate the loss of potential resulting from the circular flow of the blade ends tips on the airscrew.

2018101230 05 Apr 2019 [0008] A whirl of contrary direction and of equal angular momentum (or impulse momentum) is induced at the ends of the airscrew blades, which by this eliminates or significantly reduces the whirls appearing at the end of wide blades and causing losses. As a result of this, a tractive force evolves on the airscrews and the range of action of the aircraft as well as the time spent on flying can be increased.

[0009] Its application is also recommended on wind turbine rotor blades. If applied, it reduces the resonant vibrations occurring on the blades and the turbines, and thus extending their lifetime significantly. Using aerodynamic braking the forming of the pivoting tip is more effective and less vibrating. The pivoting tips are working as slotted flaps.

Claims

2018101230 05 Apr 2019

Patent claims:

1. Air screw-, fan-, and wind turbine blades with wide blade tips for use in an axial flow rotor stage, having a body with pressure and suction surfaces on opposite sides of the blade, a span extending between a root and a tip and a chord extending between a leading edge and a trailing edge, characterised in that formed in the end tip of the blade there is a notch which extends between the pressure and suction sides, and a channel leading to the notch - on the pressure side formed through the body of the blade between said pressure and suction surfaces, wherein the distance between the end tip of the blade and the notch changes in the diameter of the blades from 1.2 % to 1.67 % along the length of the notch.
2. Air screw-, fan-, and wind turbine blades with wide blade tip as claimed in claim 1 wherein the notch - for ensuring strength - can be divided to sections with small interruptions.
3. Air screw-, fan-, and wind turbine blades with wide blade tip as claimed in claim 2 wherein the length of the notch is approximately 60% of the length of the tip of the blade.
4. Air screw-, fan-, and wind turbine blades with wide blade tip as claimed in any preceding claim wherein the width of the notch is 3.53 % of the length of the notch.
5. Air screw-, fan-, and wind turbine blades with wide blade tip as claimed in any preceding claim wherein the root of the notch is formed near the trailing edge.