CN114383802A - Pneumatic optimization method for double-arc wind tunnel corner guide vane, guide vane and wind tunnel - Google Patents

Abstract

The invention discloses a pneumatic optimization method for a double-arc wind tunnel corner guide vane, the guide vane and a wind tunnel, wherein the double-arc guide vane has a given large chord length spacing ratio, the double-arc guide vane has an arc windward surface and an arc leeward surface, and the tail edges of the windward surface and the arc leeward surface are both arcs, wherein the optimization method comprises the following steps: acquiring an outlet airflow deflection angle theta behind the tail edge of the double-arc guide vane, wherein the airflow deflection angle theta is an included angle between the axis direction of the wind tunnel at the downstream of the corner and the outlet airflow direction of the guide vane; based on the airflow deflection angle theta, optimizing the tail edge configuration of the flow deflector to enable the windward side of the tail edge to be changed into a first straight line from an arc line, the leeward side of the tail edge to be changed into a second straight line from an arc line, and the intersection point of the first straight line and the second straight line to be used as the top point of a new tail edge; and rotating the flow deflector to increase the installation angle of the flow deflector by a set angle, so that the outlet airflow direction of the flow deflector is parallel to the axial direction of the wind tunnel at the downstream of the corner, and the installation angle is the included angle between the chord length direction of the flow deflector and the axial direction of the wind tunnel at the upstream of the corner.

Description

A kind of aerodynamic optimization method, deflector and wind tunnel for corner deflector of double arc wind tunnel

technical field

The invention belongs to the field of aerospace engineering, and in particular relates to an aerodynamic optimization method for a corner deflector of a double-arc wind tunnel, a deflector and a wind tunnel.

Background technique

With the vigorous development of the civil aviation industry, the requirements for airworthiness certification of aircraft are becoming more and more stringent. As the mainstream test equipment for aerodynamic noise research, the aero-acoustic wind tunnel has entered the climax of construction.

Wind tunnel corner deflectors are mainly used in low-speed recirculation wind tunnels, and their function is to improve the flow field quality at the corners and reduce the flow loss of the wind tunnel. In the aero-acoustic wind tunnel, the wind tunnel corner deflector also has an important role: as a sound-absorbing component to reduce the noise level propagating in the wind tunnel.

The commonly used corner deflector types in conventional wind tunnels include arc plate type, SA wing type and double arc type. Due to the aero-acoustic wind tunnel's noise reduction requirements for the deflector, the deflector needs a certain thickness to fill the sound-absorbing material, so the double arc type is more suitable. At the same time, in order to improve the noise reduction effect, the chord-to-length ratio of the guide vane installation needs to be increased. As shown in Figure 1 and Figure 3, in conventional use, the chord length-to-spacing ratio (c/d) of the corner deflectors in the double-arc wind tunnel is 1.4 to 2.5. In the aeroacoustic wind tunnel, the double-arc corner deflector The chord length-to-spacing ratio will be increased to 3.5 to 5, as shown in Figures 2 and 4. The improvement of the chord length to spacing ratio increases the number of guide fins and reduces the relative distance between adjacent guide fins, which will increase the maximum velocity of the airflow when it flows through the guide fins, and at the same time the guide fins guide the airflow. Enhanced effect. Referring to Fig. 4, under the same installation angle α of the guide vane, when the chord length spacing ratio is large, the airflow at the outlet of the guide vane deviates from the axis direction of the wind tunnel downstream of the corner, resulting in an increase in the flow loss downstream of the guide vane, a decrease in the quality of the flow field, and additional aerodynamic noise.

Therefore, it is expected that an aerodynamic optimization design method for the corner deflector of the double-arc wind tunnel can solve the problems of serious acceleration of the leading edge airflow and excessive deflection of the outlet airflow direction caused by the installation with a large chord-to-length spacing ratio.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose an aerodynamic optimization method for the corner deflector of a double arc wind tunnel, which can achieve the purpose of reducing the maximum speed of the leading edge of the deflector and correcting the outlet airflow direction without excessively increasing the extra structural length.

In order to achieve the above purpose, the present invention provides a method for aerodynamic optimization of a double-arc wind tunnel corner deflector. The windward surface and the leeward surface are arc-shaped, and the trailing edges of the windward surface and the leeward surface are arcs, and it is characterized in that, the method includes:

Obtain the outlet airflow deflection angle θ behind the trailing edge of the double-arc guide vane, and the airflow deflection angle θ is the angle between the axial direction of the wind tunnel downstream of the guide vane and the airflow direction at the outlet of the guide vane;

Based on the airflow deflection angle θ, the configuration of the trailing edge of the guide vane is optimized, so that the windward surface of the trailing edge is transformed from an arc to a first straight line, and the leeward surface of the trailing edge is transformed from an arc is a second straight line, and the intersection of the first straight line and the second straight line serves as the vertex of the trailing edge;

Rotate the guide vane to increase the installation angle of the guide vane by a set angle, and make the direction of the airflow at the outlet of the guide vane parallel to the axial direction of the downstream wind tunnel at the corner, and the installation angle is the direction of the chord length of the guide vane The angle with the direction of the wind tunnel axis upstream of the corner.

In an optional solution, the optimizing the trailing edge of the guide vane includes:

A first optimization point is determined on the windward surface of the trailing edge, so that the included angle between the inner tangent of the deflector passing through the first optimization point and the axial direction of the downstream wind tunnel is β, and the angle between β and the airflow is β. The folding angle θ meets the set correlation degree;

A second optimization point is determined on the windward surface of the trailing edge, so that the line connecting the first optimization point and the second optimization point is parallel to the diagonal direction of the corner, and the diagonal direction of the corner is the direction of the line connecting the vertices of the trailing edges of the two adjacent pieces of the deflector;

The inner tangent and the outer tangent of the deflector passing through the second optimized point are the first straight line and the second straight line, respectively.

In an optional solution, the set correlation degree is: 0.5θ≤β≤2.5θ.

In an optional solution, the method for obtaining the airflow deflection angle includes: obtaining through simulation or estimating and obtaining according to an empirical value.

In an optional solution, the chord length-to-spacing ratio is 3.5-5.

In an optional solution, the β=θ, and the rotating the guide vane includes: rotating the guide vane in a direction in which the installation angle of the guide vane increases by an angle of θ.

The present invention also provides a double-arc wind tunnel corner guide fin, the guide fin has a large chord-length-to-spacing ratio, and the guide fin is designed by the above method.

In an optional solution, the chord length-to-spacing ratio is 3.5-5.

The present invention also provides an aero-acoustic wind tunnel, the aero-acoustic wind tunnel includes a corner of the wind tunnel, and the above-mentioned double-arc wind tunnel corner deflector is arranged at the corner of the wind tunnel.

The beneficial effects of the present invention are:

By modifying the aerodynamic profile of the trailing edge of the guide vane, the invention changes the arc at the trailing edge of the guide vane at the original corner into a straight line, which weakens the deflection effect of the trailing edge of the guide vane on the airflow direction, and optimizes the large chord length-to-spacing ratio. At the same time, the chord length of the guide vane does not change much, and the structural length of the guide vane is not excessively increased. By adjusting the installation angle of the guide vanes, the airflow channel formed by the two adjacent guide vanes becomes wider near the leading edge, which reduces the maximum airflow speed, reduces the friction resistance of the guide vanes and reduces the flow noise.

The present invention has other features and advantages which will be apparent from or will be apparent from the accompanying drawings and the following detailed description incorporated herein Rather, the drawings and the detailed description serve to explain certain principles of the invention.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of the exemplary embodiments of the present invention in conjunction with the accompanying drawings.

Figure 1 shows a specific implementation case where the small chord length-to-spacing ratio double-arc guide vanes are installed in the corner of the wind tunnel.

Fig. 2 shows a specific implementation case where the large chord length-to-spacing ratio double-arc guide vanes are installed in the corner of the wind tunnel.

Fig. 3 shows the small chord-length-to-spacing ratio double-arc corner guide vanes in a conventional wind tunnel (two guide vanes are used to indicate the relative positions between the guide vanes).

Figure 4 shows a double arc corner deflector with a large chord-length-to-spacing ratio in an aeroacoustic wind tunnel.

Fig. 5 shows a method to solve the excessive deflection of the outlet airflow when the double-arc wind tunnel corner deflector has a large chord-length-to-spacing ratio.

Figure 6 shows another method to solve the excessive deflection of the outlet airflow when the double-arc wind tunnel corner deflector has a large chord length-to-spacing ratio.

FIG. 7 shows a schematic diagram of a method for aerodynamic optimization of a corner deflector in a double-arc wind tunnel according to an embodiment of the present invention.

FIG. 8 shows a schematic diagram of the rotation of the corner deflector of the double-arc wind tunnel according to an embodiment of the present invention (the dotted line is before rotation, and the solid line is after rotation).

FIG. 9 is a schematic diagram showing the comparison before and after the optimization of the corner deflector in a double-arc wind tunnel according to an embodiment of the present invention.

Detailed ways

The present invention will be described in more detail below. While the present invention provides preferred embodiments, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limiting the invention.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; it can be mechanical connection, direct connection, or indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In the background art, when the double-arc wind tunnel corner deflector has a large chord-length-to-pitch ratio, the outlet airflow is excessively deflected, and currently, two methods are often used to solve the problem.

Method 1, as shown in Figure 5, adjusts the outlet airflow direction to be along the wind direction by reducing the installation angle α of the guide vane (the installation angle of the guide vane is the angle between the chord length direction of the guide vane and the axial direction of the upstream wind tunnel). Hole Pipe Axial. This method only considers the adjustment of the outlet air flow, and does not consider the influence of the air flow at the leading edge of the guide vane after the installation angle is adjusted. With the adjustment of the installation angle of the guide vane, the airflow channel formed between the two guide vanes has changed. After the guide vane installation angle becomes smaller, the airflow channel near the leading edge of the guide vane becomes narrower, resulting in accelerated airflow in this section. This is accompanied by an increase in flow resistance losses and an increase in flow noise.

Method 2, as shown in Figure 6, this method keeps the position of the leading edge of the guide vane unchanged, extends the trailing edge of the guide vane straightly, and forms a long channel with approximately equal cross-section at the tail of the guide vane. The direction is consistent with the axis direction of the downstream wind tunnel, so as to correct the direction of the airflow at the outlet of the guide vane to the direction along the axis of the downstream wind tunnel. This method requires a long straight extension to correct the direction of the outlet airflow, resulting in increased resistance loss and increased manufacturing and installation costs. At the same time, the method ignores the effect of accelerated airflow near the leading edge of the guide vane after the chord-to-spacing ratio of the guide vane increases.

All the existing methods simply correct the airflow direction at the outlet of the guide vane, but do not optimize the aerodynamic characteristics of the leading edge of the guide vane, and even further aggravate the deterioration.

In order to solve the problem of serious acceleration of the leading edge air flow and excessive deflection of the outlet air flow caused by the installation with a large chord length spacing ratio. The purpose of reducing the maximum speed of the leading edge of the guide vane and correcting the direction of the outlet airflow is achieved without increasing the length of the extra structure. An embodiment of the present invention provides a method for aerodynamic optimization of a double-arc wind tunnel corner deflector. Referring to FIG. 2, FIG. 7 to FIG. 9, FIG. A concrete example of implementation in the corner of the wind tunnel. The double-arc guide vane has a given large chord-length-to-spacing ratio, and the double-arc guide vane has an arc-shaped windward surface and a leeward surface, and the trailing edges of the windward surface and the leeward surface are both. arc, the method includes:

Obtain the outlet airflow deflection angle θ behind the trailing edge of the double-arc guide vane, and the airflow deflection angle θ is the angle between the axial direction of the wind tunnel downstream of the guide vane and the airflow direction at the outlet of the guide vane;

Based on the airflow deflection angle θ, the configuration of the trailing edge of the guide vane is optimized, so that the windward surface of the trailing edge is transformed from an arc to a first straight line, and the leeward surface of the trailing edge is transformed from an arc is a second straight line, and the intersection of the first straight line and the second straight line serves as the vertex of the trailing edge (the trailing edge of the new deflector);

Rotate the guide vane to increase the installation angle of the guide vane by a set angle and make the outlet airflow direction parallel to the axial direction of the downstream wind tunnel. The installation angle is the chord length direction of the guide vane and the upstream wind of the corner. The included angle in the direction of the hole axis.

Specifically, in this embodiment, the chord-length-to-spacing ratio of the double-arc guide vanes is 3.5-5. For a given large chord length-to-spacing ratio (such as in the design of aeroacoustic wind tunnels, the required chord length and spacing of the guide vanes can be given according to the noise reduction index proposed for the corner guide vanes, thereby obtaining the required chord length Spacing ratio), which corresponds to an airflow deflection angle θ, which can be obtained according to the numerical simulation results or estimated according to empirical values.

In this embodiment, optimizing the trailing edge of the guide vane includes: determining a first optimization point on the windward surface of the trailing edge, so that the inner tangent of the guide vane passing through the first optimized point is connected to the downstream wind tunnel The included angle of the axis direction is β, and the β and the airflow deflection angle θ satisfy the set correlation (eg 0.5θ≤β≤2.5θ); the second optimization point is determined on the windward surface of the trailing edge, Make the connection line between the first optimization point and the second optimization point parallel to the diagonal direction of the corner, and the diagonal direction of the corner is the adjacent two pieces of the guide vanes (the guide before unoptimized). The connecting line direction of the apex of the trailing edge; the inner tangent and the outer tangent of the guide vane passing through the second optimization point are the first straight line and the second straight line, respectively.

Specifically, according to the airflow deflection angle θ obtained in the first step, the geometry of the trailing edge is optimized for the corner deflector of the double-arc wind tunnel. After the optimization of this step, the deflecting effect of the trailing edge of the guide vane on the airflow direction is weakened.

1. Find the first optimized point 7 on the windward surface of the trailing edge of the deflector, so that the angle between the inner tangent 6 of the deflector passing through the first optimized point 7 and the direction of the downstream wind tunnel axis 2 is θ (in other embodiments, The included angle ranges from 0.5θ to 2.5θ). The inner tangent line 6 (the first straight line) is the aerodynamically optimized profile of the windward surface of the trailing edge of the deflector.

2. Find the second optimized point 8 on the leeward surface of the trailing edge of the deflector. The outer tangent 5 (second straight line) of the deflector passing through the second optimized point 8 is the aerodynamic optimization profile of the leeward surface of the trailing edge of the deflector. A parallel line 10 in the corner diagonal direction 9 is made through the first optimization point 7 , and the intersection point of the straight line 10 and the leeward surface of the guide vane is the second optimization point 8 . The leeward side aerodynamic profile 3 and the windward side aerodynamic profile 4 are the new deflector aerodynamic profiles optimized for the trailing edge.

The new guide vane after the optimal design of the trailing edge obtained in the previous step, and then adjust the leading edge position of the guide vane. As shown in FIG. 8 , the guide vane is rotated clockwise at the rotation base point 12 by an angle θ (so that the outlet airflow direction 11 is parallel to the axial direction 2 of the downstream wind tunnel at the corner). Compared with before, the flow channels between adjacent guide vanes near the leading edge of the vanes are expanded, the maximum airflow velocity is reduced, and the flow field is optimized.

The determination of the first optimization point 7 and the second optimization point 8 and the determination of the rotation angle provided in this embodiment are not unique. For example, when determining the first optimization point 7, the angle between the inner tangent 6 and the axis direction of the downstream wind tunnel can be taken as 2θ, the position of the second optimization point 8 can also be reliably forward or backward, and the rotation angle can also be adjusted according to other parameters (only Ensure that the airflow direction 11 at the outlet of the guide vane after rotation is parallel to the axial direction 2 of the downstream wind tunnel). Therefore, in practice, the three optimization parameters of the first optimization point 7 , the second optimization point 8 and the rotation angle of the guide vane have various combinations, and this embodiment only provides a relatively simple parameter determination scheme.

The method of the invention carries out aerodynamic optimization on the double-arc corner guide vanes with large chord length-to-spacing ratio. By modifying the aerodynamic profile of the trailing edge of the guide vane, the arc at the trailing edge of the guide vane at the original corner is changed to a straight line, so that the deflection effect of the trailing edge of the guide vane on the airflow direction is weakened, and the double chord length spacing ratio is optimized. The airflow direction field at the outlet of the arc corner deflector, and the length of the deflector structure is not greatly increased. By increasing the installation angle of the guide vanes, the airflow channel formed by the adjacent guide vanes becomes wider near the leading edge of the guide vanes, which reduces the maximum airflow speed between the guide vanes, reduces the frictional resistance of the guide vanes, and reduces the frictional resistance of the guide vanes. Reduce flow noise. Compared with the existing method, the method of the present invention not only solves the problem of the airflow direction at the outlet of the guide vane, but also optimizes the flow field near the leading edge of the guide vane without excessively increasing the structural length of the guide vane.

Various embodiments of the present invention have been described above, and the foregoing descriptions are exemplary, not exhaustive, and not limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (9)

1. A pneumatic optimization method for a double-arc wind tunnel corner guide vane is characterized in that the double-arc wind tunnel corner guide vane has a given large chord length spacing ratio, the double-arc guide vane has arc windward sides and arc leeward sides, and the tail edges of the windward sides and the arc leeward sides are arc lines, and the method comprises the following steps:

acquiring an outlet airflow deflection angle theta behind the tail edge of the double-arc flow deflector, wherein the airflow deflection angle theta is an included angle between the axis direction of the wind tunnel at the downstream of the corner and the outlet airflow direction of the flow deflector;

optimizing the configuration of the tail edge of the guide vane based on the airflow deflection angle theta, so that the windward side of the tail edge is changed into a first straight line from an arc line, the leeward side of the tail edge is changed into a second straight line from an arc line, and the intersection point of the first straight line and the second straight line is used as the vertex of the tail edge;

and rotating the flow deflector to increase the installation angle of the flow deflector by a set angle, and enabling the outlet airflow direction of the flow deflector to be parallel to the axial direction of the wind tunnel at the downstream of the corner, wherein the installation angle is the included angle between the chord length direction of the flow deflector and the axial direction of the wind tunnel at the upstream of the corner.

2. The bi-arc wind tunnel corner vane aerodynamic optimization method of claim 1, wherein the optimizing the trailing edge of the vane comprises:

determining a first optimization point on the windward side of the trailing edge, so that an included angle between an internal tangent of a flow deflector passing through the first optimization point and the axis direction of a wind tunnel at the downstream of a corner is beta, and the beta and the air flow deflection angle theta meet a set correlation degree;

determining a second optimization point on the windward side of the trailing edge, so that the connecting line of the first optimization point and the second optimization point is parallel to the diagonal direction of the corner, wherein the diagonal direction of the corner is the connecting line direction of the vertexes of the trailing edges of the two adjacent guide vanes;

the inner tangent line and the outer tangent line of the guide vane passing through the second optimization point are respectively the first straight line and the second straight line.

3. The pneumatic optimization method for the bi-arc wind tunnel corner deflectors according to claim 2, wherein the set correlation degree is as follows: beta is more than or equal to 0.5 theta and less than or equal to 2.5 theta.

4. The pneumatic optimization method for the bi-arc wind tunnel corner baffle according to claim 1, wherein the method for obtaining the deflection angle of the airflow comprises the following steps: obtained through analog simulation or estimated according to empirical values.

5. The pneumatic optimization method for the bi-arc wind tunnel corner deflectors according to claim 1, wherein the chord length to pitch ratio is 3.5-5.

6. The aerodynamic optimization method of bi-arc wind tunnel corner deflectors of claim 2, wherein β θ, said rotating said deflectors comprises: and the angle for rotating the guide vane towards the direction of increasing the installation angle is theta.

7. A bi-arc wind tunnel corner baffle having a large chord length to pitch ratio, wherein the baffle is designed by the method of any one of claims 1-6.

8. The bi-arc wind tunnel corner baffle of claim 7, wherein the chord length to pitch ratio is from 3.5 to 5.

9. An aeroacoustic wind tunnel, characterized in that the aeroacoustic wind tunnel comprises a wind tunnel corner, wherein the wind tunnel corner is provided with the bi-arc wind tunnel corner deflectors of claims 7-8.

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