WO2014121554A1

WO2014121554A1 - Design method for three-dimensional curved airfoil section

Info

Publication number: WO2014121554A1
Application number: PCT/CN2013/074018
Authority: WO
Inventors: 陈宇奇
Original assignee: 新疆尚孚新能源科技有限公司
Priority date: 2013-02-05
Filing date: 2013-04-10
Publication date: 2014-08-14
Also published as: CN103967718B; EA201500723A1; CN103967718A; EA029645B1

Abstract

Disclosed is a design method for a three-dimensional curved airfoil section. The method comprises the following steps: collecting arc coordinate data of a conventional 2D airfoil section such as (x₁, y₁) and (x₂, y₂); according to the conventional airfoil section coordinate data, calculating an increment such as ΔL₁ and ΔL₂ between each x coordinate point of a chord; determining a radius of rotation R of the airfoil section to be arranged according to the design; selecting x₁=z₁=0.707R, where y₁=0; inserting x₁, z₁, ΔL₁ and R into a specific formula to calculate x₂ and z₂, thereby creating a three-dimensional airfoil section arc coordinate (x₂, y₂, z₂), wherein y₂ is still a coordinate value of the thickness of the 2D airfoil section; and by this analogy, calculating a three-dimensional airfoil section arc coordinate cluster (x₃, y₃, z₃), etc. This method improves the aerodynamic profile of a blade by means of optimising a three-dimensional curved airfoil section, thereby increasing aerodynamic force efficiency of a rotary blade on the basis of the same materials and structural arrangement.

Description

Design method of three-dimensional curved airfoil

Technical field

The invention relates to a design method of a three-dimensional curved airfoil, which is not only for a wind turbine blade of a renewable energy type, but also for various types of aircraft with a rotary wing, a jet engine, a steam/gas turbine and an extra large turbine blade, etc. It can be used as a basic geometric unit for constructing various wings, rotors and blades. Background technique

The helicopter is a vertical landing gear with its rotor as its main source of lift. Its vertical takeoff and landing, air hovering and other performances are largely determined by the aerodynamic characteristics of the rotor, which is related to the aerodynamic shape of the rotor blades. Has a very close relationship. Therefore, the rotor airfoil, which is the basic element of the aerodynamic shape of the rotor blade, has an important influence on the flow field and aerodynamic characteristics of the helicopter rotor. It also plays a significant role in improving the maneuverability, cruising speed and noise reduction characteristics of the helicopter. Therefore, the development of advanced helicopter rotor airfoil aerodynamic design research is of great significance to improve rotor performance and improve helicopter performance. At present, foreign advanced helicopters are equipped with rotor-specific airfoils. For example, the Russian Mi-28N Holocaust gunship adopts the new TsAGI series airfoil, which enables it to continuously complete Nesterov flipping and Yin Maiman flipping in flight. , dead muscles and roll, and these difficult aerobatics can only be completed before the Mi-28N helicopter. It can be seen that the helicopter airfoil performance has reached a high level, mainly in the improvement of lift, the improvement of stall characteristics, and the reduction of noise level. In China, although the aerodynamic design technology of helicopter rotor has made great progress, there is still a big gap between the design of rotor airfoil and advanced countries. There is no helicopter-specific airfoil with independent intellectual property rights. Therefore, it is worthwhile to carry out in-depth research and design work on new helicopter airfoils. However, designing the helicopter rotor airfoil is a rather daunting task. First of all, due to the rotation of the blade, the relative inflow velocity of each profile airfoil changes continuously from low speed to high speed in the span direction, causing severe aerodynamic interference between the blades, a paddle-vortex interference phenomenon in the flow field, and a complicated spiral. Wake, and at When flying at a high speed, the front blade may have a shock stall, and the trailing blades may have air separation. The flow field of the helicopter rotor is very complicated, and it is difficult to accurately simulate it. Secondly, although the current airfoil design methods have made great progress, they all have their own shortcomings, and the development is not perfect.

Early airfoil research relied on the experience of designers and relied on wind tunnel tests. The most representative airfoils in this period were the NACA series in the United States, the TsAGI series in Russia, and the FFW series in Europe. In the 1950s, especially after entering the transonic and supersonic eras, due to limitations in experimental conditions, etc., relying solely on experience and wind tunnel tests could not meet the requirements, and the development of airfoil became very slow. After entering the 1970s, with the development of computer capabilities and numerical calculation methods, the design level of the airfoil has been greatly improved. In particular, the computational fluid dynamics (CFD) method has fully exploited the advantages of saving development costs, shortening the development cycle, and reducing design costs. Therefore, the airfoil design based on CFD method has become a research hotspot.

In order to effectively use the power from the air, people will use structures with specific aerodynamic shapes, such as the wing of an aircraft, commonly known as "wings", blades of wind turbines, etc. to achieve this goal. At present, these specific shapes are invariably constructed by a combination of various airfoil types, that is, the airfoil of the rotor and the blade are superimposed by a two-dimensional plane airfoil, as shown in Fig. 1. Figure 2, Figure 3. Currently all wings of the world 2D airfoil data. Its geometric envelope constitutes the first calculation of the bone ^

Then calculate the arc coordinate on the airfoil and the lower arc coordinate ix _L ,

Vu = 3⁄4 + y _t cos 0,

among them, θ = aictaii

The airfoil envelope diagram can be drawn by coordinates, as shown in Figure 4.

Because the airfoil envelope is flat, when the two-dimensional plane airfoil is rotated, its sweeping trajectory will form a torus in the plane of rotation. The defects are: due to the geometric envelope of the two-dimensional plane airfoil Like translation, in the case of rotation, it will not be able to achieve full-pass mechanical wrapping with the flow of the Euler streamline. Summary of the invention

The task of the invention is to improve the aerodynamic extraction efficiency of the rotating blade on the basis of the same material and structural arrangement by constructing an optimized three-dimensional curved airfoil and then changing the aerodynamic shape of the blade.

The three-dimensional curved airfoil of the present invention is formed from the perspective of kinematics, as shown in Fig. 6.

After analysis, the mining force of the aircraft wing is mainly in the state of translation, and the traction of the helicopter rotor and the wind turbine blade is in the state of rotation. This three-dimensional curved airfoil invention will better conform to and improve the mining function of rotating blades and rotary blades in kinematics and aerodynamics.

The present invention is based on the above-described two-dimensional plane envelope (NACA series in the United States, TsAGI series in Russia, FFA series in Europe, and other y-axis ordinate-corrected airfoil series, etc.), and is determined by the radius R of rotation in the blade length direction. The body is attached to the cylinder to generate a three-dimensional curved airfoil. According to Figure 5, the chord length growth relationship is: tan [ h arctan(

R

= R ² - 3⁄4 The blade chord is long. Finally, the coordinates of the airfoil envelope in the three-dimensional space (on the cylindrical body), the upper arc is ίχ _υ , γ _υ , ζ _υ ) ; the lower arc is ix _L , y _L , _Zu ) , which constitutes the rotation The three-dimensional curved airfoil of the blade, see Figure 6.

The specific steps of the present invention are as follows:

A method for designing a three-dimensional curved airfoil, comprising the steps of:

a) Extract the conventional 2-D airfoil arc coordinate data ( _Xl , _Yl ), (3⁄4, y ₂ ) ... ; Calculate the increment Δ厶 between the X coordinate points of the string according to the conventional airfoil coordinate data. Δ厶... Δ厶(Δ 厶= X _i+1 - 3⁄4); Determine the radius of rotation R of the airfoil to be arranged according to the design; b) Select = _Zl = 0.707 R; _yi = 0 at this time;

c) Bring _Xl , _Zl , Δ厶 and R into the formula

2

= ^TL , _ZL , _Ί

Tan [ h arctan( ~―)] + 1

R x _x

z ₂ = R ² ― X2

d) Calculate X2, z _2:

e) construct 3D airfoil arc coordinate data (3⁄4, , y ₂ ), Note: y ₂ is still the 2-D airfoil thickness coordinate value;

Repeat steps (d) and (e) progressively to obtain a three-dimensional coordinate cluster of airfoil arcs, (x ₃ , Z3, y ₃ ).

The above y is still the 2-D airfoil thickness coordinate value, and can also be the y correction value of other airfoil series. For the industrial application invention, its biggest joint advantage is that by constructing an optimized three-dimensional curved airfoil and then changing the aerodynamic shape of the blade, the aerodynamic extraction efficiency of the rotating blade is improved on the basis of the same material and structural arrangement. DRAWINGS

Figure 1. Structure of an aircraft wing assembled from different two-dimensional planar airfoils

Figure 2. A perspective view of the aerodynamic shape of existing wind turbine blades assembled from various 2D planar airfoils; their chord length and torsion angle are all changed according to certain rules.

Figure 3. Schematic representation of existing steam turbine blades and helicopter rotors consisting of specific airfoils; they are all constructed of two-dimensional planar airfoils.

Figure 4. The existing planar airfoil envelope diagram

Figure 5. Schematic diagram of the growth relationship of the string coordinates along the rotating cylindrical body of the present invention

Figure 6. Comparison of a three-dimensional curved airfoil (B) and a two-dimensional planar airfoil (A) of a rotating blade of the present invention.

The following table is a three-dimensional coordinate value of the three-dimensional curved airfoil of the present invention on a rotating cylinder (R: 10.26 m), which is a specific embodiment of the present invention. The first three sets of data in each line are the three-dimensional coordinates of the upper arc; the last three sets of data in each line are the three-dimensional coordinates of the lower arc.

Replacement page (Article 26) 6323. 38 8079. 76 284. 43 6323. 38 8079. 76 -119. 64

6223. 47 8156. 96 267. 18 6226. 28 8154. 82 -103. 58

6122. 87 8232. 74 245. 76 6128. 03 8228. 91 - 85. 76

6021. 68 8307. 05 220. 86 6028. 57 8302. 05 - 66. 98

5919. 93 8379. 86 193. 07 5927. 89 8374. 23 -47. 86

5817. 66 8451. 18 162. 95 5825. 99 8445. 44 -29. 23

5714. 93 8520. 98 131. 22 5722. 83 8515. 68 -12. 30

5611. 74 8589. 29 98. 68 5618. 45 8584. 90 1. 87

5508. 07 8656. 14 65. 89 5512. 90 8653. 06 11. 35

5403. 88 8721. 56 33. 47 5406. 25 8720. 09 13. 74

5298. 85 8785. 77 0. 00 5298. 85 8785. 77 0. 00

The specific steps of the present invention are described as:

f) Extract the arc data (or lower arc) coordinate data ( _Xl , y. ), ( , y ₂ ) on any conventional 2-D airfoil ...

g) Calculate the increment Δ Α, Δ between the X coordinate points of the string according to the conventional airfoil coordinate data.

X _i+1 -Xi)

h) Determine the radius of rotation (position) of the airfoil (including the rotor and the rotating blade) to be arranged according to the design. R

i) Select = two 0. 707 R; at this time two 0.

j) Bring _Xl , _Zl , and R into the formula

z 2 = R ² - x ₂ calculates χ ₂ , z ₂

k) Construct 3D airfoil arc coordinate data (3⁄4, z ₂ , y ₂ ).

Note: y ₂ " y is still the 2-D airfoil thickness coordinate value and the y correction of other airfoil series.

1) Repeat steps (e) and (f) progressively to obtain the upper (or lower) arc replacement page (rule 26) Dimensional coordinate cluster,

(X3, z ₃ , y ₃ )

(X4> z ₄ , y^)

(X, Z, y)

26)

Claims

Claim

a) Extract the conventional 2-D airfoil arc coordinate data ( _Xl , _Yl ), (χ ₂ , y ₂ ) . . . ; Calculate the increment Δ厶 between the X coordinate points of the string according to the conventional airfoil coordinate data. , Δ厶. . . Δ厶(Δ 厶= X _i+1 - Xi); Determine the radius of rotation R of the airfoil to be arranged according to the design; b) Select xi = zi = 0. 707 R, at this time = 0; c) Bring _Xl , _Zl , Δ厶 and R into the formula

2

^ = ΔΕ , _ZL , Ί _Λ

Tan L h arctan( ~―) J + 1

R _x

z ₂ ² = R ² — x ₂ ² d) Calculate x ₂ , z ₂ ; e) Construct 3D airfoil arc coordinate data (x ₂ , z ₂ , y ₂ ), Note: y ₂ is still 2-D Airfoil thickness coordinate value;

f) Repeat steps (d), (e) progressively to obtain the three-dimensional coordinate cluster of the airfoil arc, (Χ3, z ₃ , y ₃ ).

2. A method of designing a three-dimensional curved airfoil according to claim 1, wherein y is a 2-D airfoil thickness coordinate value.

3. A method of designing a three-dimensional curved airfoil according to claim 1, wherein y is a y correction value of the 2-D airfoil series.