Device for obtaining repeatable test result of slender revolution body under large attack angle

Abstract

The invention relates to a device for obtaining a repeatable test result of a slender revolution body under a large attack angle. The device comprises a head tip, a head body, a projectile body, a fastener and a turbulent flow bulge, the head tip downstream part is connected with the head body upper part, the head tip is fixed on the head body through a fastener, and the head body downstream part is connected with the missile body upper part; the turbulent flow protrusions are fixed to the surface of the head tip. By fixing the turbulent flow protrusion on the head tip, disturbance caused by the turbulent flow protrusion becomes a leading factor influencing asymmetric separation, uncertain influence caused by irregular disturbance of incoming flow is shielded, and a repeatable test result of the slender revolution body under a large attack angle is obtained. By changing the rotation angle of the head tip relative to the head body, the influence of the roll angle change of the head tip on the asymmetric separation is researched, and the bistable characteristic of the asymmetric separation is researched. The method solves the technical problem that the test result in the asymmetric separation characteristic research of the slender revolution body cannot be repeated.

Description

Technical Field

[0001] The invention belongs to the technical field of wind tunnel tests of slender rotating bodies at large attack angles, and relates to a device for obtaining repeatable test results of slender rotating bodies at large attack angles. Background Art

[0002] The modern battlefield has put forward more stringent requirements on the maneuverability of aircraft. In actual combat, aircraft need to complete rapid turns and nose pointing in a short period of time. In this process, the aircraft will face ultra-large angle of attack flight conditions. Its maneuverability and flight performance at large angles of attack are the key to its ability to win the battle on the battlefield. This makes the flow characteristics of aircraft at large angles of attack a research hotspot.

[0003] In order to reduce the shock wave drag as much as possible, the forebody of supersonic aircraft is mostly designed as a slender rotating body. With the increase of the angle of attack, the flow field state in the leeward area of ​​the slender rotating body undergoes attachment flow, symmetrical separation, asymmetrical separation and unsteady vortex shedding in sequence. The asymmetrical separation in the leeward area will induce uncontrollable lateral force and yaw moment, which seriously affects the lateral stability of the aircraft. The asymmetric separation of the slender rotating body under large angle of attack conditions also has a bistable characteristic, that is, the lateral force induced by the asymmetric back vortex only switches between the positive maximum value and the negative minimum value with the change of the nose tip roll angle. At this time, the asymmetric back vortex has two stable distribution regular states, which is called bistable. The bistable characteristic is an important content in the study of asymmetric separation characteristics.

[0004] A large number of experimental research results show that the asymmetric separation of slender rotating bodies at large angles of attack is affected by disordered disturbances in the wind tunnel flow and processing defects in the model head. This leads to the fact that when other experimental conditions are the same, the test results of the same model under different blowing machines or the test results obtained using models from different processing batches are not repeatable, which makes it extremely difficult to use experimental means to study the asymmetric separation characteristics of slender rotating bodies at large angles of attack.

[0005] In view of this, it is necessary to design a test device that can solve the technical problem of non-repeatable test results in the study of asymmetric separation characteristics of slender rotating bodies at large attack angles. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to propose a device for obtaining repeatable test results of a slender rotating body at a large attack angle, and to solve the technical problem of irreproducible test results in the study of asymmetric separation characteristics of a slender rotating body.

[0007] The solution to the technical problem of the present invention is: a device for obtaining repeatable test results of a slender rotating body at a large attack angle, comprising a head tip, a head body, a projectile body, a fastener and a spoiler protrusion;

[0008] The downstream of the head tip is connected to the upstream of the head body, the head tip is fixed to the head body by a fastener, and the downstream of the head body is connected to the upstream of the body; the spoiler protrusion is fixed on the surface of the head tip;

[0009] By fixing the spoiler protrusion on the head tip, the disturbance caused by the spoiler protrusion becomes the dominant factor affecting the asymmetric separation, shielding the uncertain influence caused by the irregular disturbance of the incoming flow, and obtaining repeatable test results of the slender rotating body at a large angle of attack;

[0010] By changing the rotation angle of the head tip relative to the head body, the influence of the change of the head tip rolling angle on the asymmetric separation and the bistable characteristics of the asymmetric separation are obtained.

[0011] Furthermore, a cylindrical boss is provided downstream of the head tip, and a countersunk hole is provided upstream of the head body, and the cylindrical boss is inserted into the countersunk hole to form a cylindrical fit; an internal thread is provided downstream of the head tip, and an external thread matching the internal thread is provided on the upstream side wall of the fastener, and the head tip is fixed to the head body by the fit between the internal thread and the external thread.

[0012] Furthermore, the downstream of the head body is a cylindrical boss, the cylindrical boss is provided with a pin hole, the upstream of the body is provided with a hollow hole that cooperates with the cylindrical boss, the upstream surface of the body is provided with a pin hole, the cylindrical boss is inserted into the hollow hole to form a cylindrical fit, and the head body and the body are positioned and fixed by pins.

[0013] Furthermore, after the head tip, the head body and the elastic body are connected in sequence, the overall surface finishing is required to ensure that the outer contour of the connecting body is consistent with the surface contour of the original model and no boss appears at the joint.

[0014] Furthermore, the surface of the head tip is engraved with a first marking line and a second marking line, the first marking line is adjacent to the joint surface of the head tip and the head body, and its direction is along the generatrix direction; the second marking line is a cross-shaped marking line formed by the intersection of a marking line along the generatrix direction and a marking line along the circumferential direction.

[0015] Furthermore, a third marking line is engraved on the upstream surface of the head body, and the third marking line is composed of a plurality of marking lines arranged at predetermined angles along the circumferential direction, and is oriented along the direction of the mother line and is adjacent to the joint surface between the head tip and the head body; a fourth marking line is engraved on the downstream surface of the head body, and the fourth marking line is adjacent to the joint surface between the head body and the bullet body, and is oriented along the direction of the mother line.

[0016] Furthermore, a fifth marking line is engraved on the upstream surface of the body, the fifth marking line is adjacent to the joint surface of the head body and the body, and the direction is along the generatrix direction.

[0017] Furthermore, the position of the head body relative to the bullet body is achieved by aligning the fourth marking line and the fifth marking line.

[0018] Furthermore, the spoiler protrusion is fixed on the head tip and is located at the intersection of the second marking lines.

[0019] Furthermore, the head tip and the head body can rotate relative to each other, and the rotation angle is determined according to the alignment relationship between the first marking line and the third marking line.

[0020] The beneficial effects of the present invention compared with the prior art are:

[0021] (1) The device of the present invention has a spoiler protrusion fixed on the tip of the head. The spoiler protrusion can disturb the flow field, making the asymmetric separation of the slender rotating body at a large angle of attack certain, which can solve the technical problem of irreproducibility of experimental results in previous studies on the asymmetric separation characteristics of slender rotating bodies at large angles of attack.

[0022] (2) The head tip of the device of the present invention can make quantitative angle rotation relative to the head body, which can be conveniently used to study the influence of the change of the head tip rolling angle on asymmetric separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a device for obtaining repeatable test results of a slender rotating body at a large attack angle according to the present invention;

[0024] Description of reference numerals:

[0025] 1. Head tip; 2. Head body; 3. Spring body; 4. Fastener; 5. Spoiler protrusion; 6. First marking line; 7. Second marking line; 8. Third marking line; 9. Fourth marking line; 10. Fifth marking line. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Example 1

[0028] like Figure 1 As shown, an embodiment of the present invention provides a device for obtaining repeatable test results of a slender rotating body at a large attack angle, comprising a head tip 1, a head body 2, a projectile body 3, a fastener 4 and a spoiler protrusion 5. The downstream of the head tip 1 is connected to the upstream of the head body 2, the head tip 1 is fixed to the head body 2 by the fastener 4, the downstream of the head body 2 is connected to the upstream of the projectile body 3; the spoiler protrusion 5 is fixed on the surface of the head tip 1.

[0029] Specifically, there is a cylindrical boss downstream of the head tip 1, and a countersunk hole is provided upstream of the head body 2. The cylindrical boss can be inserted into the countersunk hole to form a cylindrical fit. The precise cylindrical fit can ensure the high concentricity between the head tip 1 and the head body 2. At the same time, the cylindrical fit does not hinder the relative rotation between the head tip 1 and the head body 2.

[0030] The present invention does not strictly limit the fastening method between the head tip 1 and the head body 2. Taking into account the convenience of model connection, in some embodiments of the present invention, the head tip 1 is provided with an internal thread downstream, and the fastener 4 is a bolt matching the internal thread. The tight connection between the head tip 1 and the head body 2 is achieved through the tightening action of the fastener 4.

[0031] Furthermore, there is a cylindrical boss downstream of the head body 2, on which a pin hole is provided, and there is a hollow hole upstream of the body 3 that cooperates with the cylindrical boss. A pin hole is provided on the upstream surface of the body 3, and the cylindrical boss can be inserted into the hollow hole to form a cylindrical fit, and the head body 2 and the body 3 are positioned and fixed by pins.

[0032] Furthermore, after the head tip 1, the head body 2 and the elastic body 3 are connected in sequence, the overall surface finishing is required to ensure that the outer contour of the connection body is consistent with the surface contour of the original model and no boss appears at the joint.

[0033] Furthermore, a first marking line 6 and a second marking line 7 are engraved on the surface of the head tip 1. The first marking line 6 is adjacent to the joint surface of the head tip 1 and the head body 2 and is oriented along the generatrix direction. The second marking line 7 is composed of a marking line along the generatrix direction and a marking line along the circumferential direction intersecting each other.

[0034] Furthermore, a third marking line 8 is engraved on the upstream surface of the head body 2, and the third marking line 8 is composed of a plurality of marking lines arranged at a certain angle along the circumferential direction, and is oriented along the direction of the busbar and is adjacent to the joint surface between the head tip 1 and the head body 2; a fourth marking line 9 is engraved on the downstream surface of the head body 2, and the fourth marking line 9 is adjacent to the joint surface between the head body 2 and the bullet body 3, and is oriented along the direction of the busbar.

[0035] Furthermore, the present invention does not impose strict restrictions on the angle interval of the marking lines in the third marking lines 8, and the angle interval can be adjusted according to actual needs.

[0036] Furthermore, a fifth marking line 10 is engraved on the upstream surface of the body 3 , and the fifth marking line 10 is adjacent to the joint surface of the head body 2 and the body 3 , and is oriented along the generatrix direction.

[0037] As a preferred embodiment, the present invention does not strictly limit the processing method of the marking lines 6-10, and it is preferred that the marking lines are clear and the positioning is accurate. In some embodiments of the present invention, the marking lines 6-10 are processed by scratching the surface of the model, and the marking depth does not exceed 0.02mm.

[0038] Furthermore, the position of the head body 2 relative to the bullet body 3 is achieved by aligning the fourth marking line 9 and the fifth marking line 10 .

[0039] Furthermore, the steps for adjusting the rotation angle of the head tip 1 relative to the head body 2 are: when it is necessary to change the rotation angle of the head tip 1 relative to the head body 2, first loosen the fastener 4, then rotate the head tip 1 to align the first marking line 6 with the marking line corresponding to the target angle in the third marking line 8, and finally tighten the fastener 4 to complete the change of the rotation angle of the head tip 1 relative to the head body 2.

[0040] like Figure 1 As shown in the partial enlarged view, the spoiler protrusion 5 is fixed at the intersection of the second marking line 7 on the head tip 1. In some embodiments of the present invention, the spoiler protrusion 5 is a zirconia ball, and the ratio of the diameter of the zirconia ball to the local diameter of the head tip 1 is about 0.082. The present invention does not strictly limit the fixing method of the spoiler protrusion 5. As a preferred solution, the zirconia ball is attached to the head tip 1 by strong glue.

[0041] The role of the spoiler protrusion 5 is explained as follows: the asymmetric separation of the slender rotating body at a large attack angle is very sensitive to the disturbance of the tip of the model head. By fixing the spoiler protrusion 5 on the tip 1, the disturbance caused by the spoiler protrusion 5 becomes the dominant factor affecting the asymmetric separation, shielding the uncertain effects caused by irregular disturbances of the incoming flow, and obtaining repeatable test results of the slender rotating body at a large attack angle.

[0042] On the basis of the above technical solution, by changing the rotation angle of the head tip 1 relative to the head body 2, the influence of the change of the head tip roll angle on the asymmetric separation can be further studied, and the bistable characteristics of the asymmetric separation can be studied.

[0043] In summary, a device for obtaining repeatable test results of a slender rotating body at a large attack angle according to an embodiment of the present invention can solve the technical problem of non-repeatable test results in the study of asymmetric separation characteristics of a slender rotating body at a large attack angle. At the same time, it is equipped with a rotatable head tip, which can be conveniently used to study the influence of the change of the head tip roll angle on the asymmetric separation.

[0044] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0045] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A device for obtaining repeatable test results of a slender rotating body at a large angle of attack, characterized in that: It comprises a head tip (1), a head body (2), a body (3), a fastener (4) and a spoiler protrusion (5); The downstream of the head tip (1) is connected to the upstream of the head body (2), and the head tip (1) is fixed to the head body (2) by a fastener (4); the downstream of the head body (2) is connected to the upstream of the projectile body (3); the spoiler protrusion (5) is fixed on the surface of the head tip (1); By fixing the spoiler protrusion (5) on the head tip (1), the disturbance caused by the spoiler protrusion (5) becomes the dominant factor affecting the asymmetric separation, shielding the uncertain influence caused by the irregular disturbance of the incoming flow, and obtaining repeatable test results of the slender rotating body at a large angle of attack; By changing the rotation angle of the head tip (1) relative to the head body (2), the influence of the change of the head tip rolling angle on the asymmetric separation and the bistable characteristics of the asymmetric separation are obtained.

2. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 1, characterized in that: A cylindrical boss is provided downstream of the head tip (1), and a countersunk hole is provided upstream of the head body (2). The cylindrical boss is inserted into the countersunk hole to form a cylindrical fit. An internal thread is provided downstream of the head tip (1), and an external thread matching the internal thread is provided on the upstream side wall of the fastener (4). The head tip (1) is fixed to the head body (2) by the fit between the internal thread and the external thread.

3. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 1, characterized in that: The head body (2) is provided with a cylindrical boss downstream, and a pin hole is provided on the cylindrical boss. The body (3) is provided with a hollow hole upstream to match the cylindrical boss. The upstream surface of the body (3) is provided with a pin hole, and the cylindrical boss is inserted into the hollow hole to form a cylindrical fit. The head body (2) and the body (3) are positioned and fixed by pins.

4. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 1, characterized in that: After the head tip (1), the head body (2) and the elastic body (3) are connected in sequence, the entire surface needs to be finely processed to ensure that the outer contour of the connection body is consistent with the surface contour of the original model and no boss appears at the joint.

5. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 1, characterized in that: The surface of the head tip (1) is engraved with a first marking line (6) and a second marking line (7); the first marking line (6) is adjacent to the joint surface of the head tip (1) and the head body (2) and is oriented along the generatrix direction; the second marking line (7) is a cross-shaped marking line formed by the intersection of a marking line along the generatrix direction and a marking line along the circumferential direction.

6. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 5, characterized in that: The upstream surface of the head body (2) is engraved with a third marking line (8), the third marking line (8) is composed of a plurality of marking lines arranged at predetermined angles along the circumferential direction, the direction is along the generatrix direction, and is adjacent to the joint surface between the head tip (1) and the head body (2); the downstream surface of the head body (2) is engraved with a fourth marking line (9), the fourth marking line (9) is adjacent to the joint surface between the head body (2) and the bullet body (3), and the direction is along the generatrix direction.

7. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 6, characterized in that: The upstream surface of the projectile body (3) is engraved with a fifth marking line (10), the fifth marking line (10) is adjacent to the joint surface of the head body (2) and the projectile body (3), and is oriented along the generatrix direction.

8. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 7, characterized in that: The position of the head body (2) relative to the bullet body (3) is achieved by aligning the fourth marking line (9) and the fifth marking line (10).

9. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 5, characterized in that: The spoiler protrusion (5) is fixed on the head tip (1) and is located at the intersection of the second marking line (7).

10. The device for obtaining repeatable test results of a slender rotating body at a large angle of attack according to claim 6, characterized in that: The head tip (1) and the head body (2) can rotate relative to each other, and the rotation angle is determined according to the alignment relationship between the first marking line (6) and the third marking line (8).

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