Engine pneumatic probe closed wind tunnel rotating window test clamp

Abstract

The invention discloses an engine pneumatic probe closed wind tunnel rotating window test clamp which comprises a disc base, the disc face of the disc base is fixedly connected with one end of a symmetrical wing-shaped supporting arm, and the other end of the symmetrical wing-shaped supporting arm is fixedly connected with the outer side wall of a cylindrical fairing. The disc base, the symmetrical wing-shaped supporting arms and the cylindrical fairing are provided with hole channels which are communicated with one another and used for installing a pneumatic probe, and the hole channels located in the symmetrical wing-shaped supporting arms are cavity holes matched with the installation part of the pneumatic probe. A detection part of the pneumatic probe penetrates through a hole channel in the cylindrical fairing and extends into the cylindrical fairing; according to the scheme, an internal flow channel of an engine is simulated through the cylindrical fairing, and meanwhile interference of turbulent flow generated by an appearance step point of the pneumatic probe on a pressure measuring hole of a detection part of the pneumatic probe is isolated; the front end of the cylindrical fairing is designed to be an annular thin-edge tip, so that turbulent flow of flowing air flow can be prevented, and the flow field quality of the air flow in the cylindrical fairing is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of wind tunnel testing, and in particular to a closed wind tunnel window rotating test fixture for an engine pneumatic probe. Background Art

[0002] 1. Wind tunnel test

[0003] Wind tunnel is a very important ground test equipment and facility in the aviation industry; wind tunnel test, numerical simulation and flight test are the three major means of aerodynamic research; the theoretical basis of wind tunnel test is the principle of relativity of motion; in actual flight, the airflow is stationary and the aircraft moves in the airflow; in the wind tunnel, the aircraft or aircraft parts, models, etc. are fixed in the wind tunnel test area and the airflow is flowing, thus simulating the relative motion between the aircraft and the airflow during flight.

[0004] A product or model needs to choose a suitable wind tunnel for testing according to the test conditions; the selection of wind tunnel mainly considers the following points: the size of the test sample and the size of the wind tunnel, the maximum test Mach number of the wind tunnel, the quality of the wind tunnel flow field, the installation interface of the wind tunnel test sample, and the special requirements of the test; whether it is an open wind tunnel or a closed wind tunnel, there is a test area that meets the flow field quality requirements; the effective test area of ​​a closed wind tunnel is generally in the central area of ​​the test section cross section, and the specific range is determined according to the flow field calibration results, which is roughly 60% to 70% of the cross section; an open wind tunnel does not have a fixed test section, and its effective test area is also determined according to the flow field calibration, and generally does not exceed 60% of the size of the contraction section outlet cross section. The test part of the test sample should be located in the effective test area of ​​the wind tunnel for testing.

[0005] 2. Disturbance flow

[0006] Laminar flow is a stable airflow movement pattern in which the airflow moves along fixed, predictable streamlines, while turbulent flow is an unstable airflow movement pattern in which there are obvious lateral movements and eddies. When laminar airflow flows on the surface of an object with a continuous (streamlined) shape and limited length, it can usually maintain a laminar state of motion. However, when the direction of the continuous change of the surface of the object is at a large angle to the direction of movement of the airflow itself, resulting in an excessively large pressure gradient in the downstream direction, it will become turbulent or eddy.

[0007] When there is a discontinuous step change on the surface of an object, the airflow is disturbed by the step point and changes dramatically, forming a turbulent and eddy mixed disturbance near the step point and downstream; the disturbance is changing all the time, causing continuous and unstable disturbances to the surrounding flow field; the shape of the disturbance is affected by many factors such as the external dimensions of the disturbance point, the flow velocity, and whether there is a constraining wall.

[0008] 3. Pneumatic probe inside the engine

[0009] A certain number of pneumatic probes need to be installed inside the aircraft engine to measure the total pressure, static pressure and other internal pressures in different areas of the engine. Before each pneumatic probe is installed on the engine, it is necessary to undergo an aerodynamic consistency test to ensure that it meets the design and manufacturing specifications. The test equipment for conducting aerodynamic consistency tests on pneumatic probes inside the engine is the wind tunnel.

[0010] The pneumatic probe in the engine can be divided into the installation part and the detection part in terms of appearance and structure; the installation part is generally completely fitted with the cavity surface reserved inside the engine, and is positioned by means of positioning pins and pin grooves; the installation part is not exposed to the airflow. The probe of the detection part extends into the flow channel inside the engine to measure the airflow pressure.

[0011] Usually, in order to install and position the pneumatic probe and fit the reserved surface inside the engine, the mounting part and the detection part of the pneumatic probe cannot achieve continuous changes in appearance. Instead, there are edges and corners with step changes, resulting in the following defects:

[0012] 1. Because there is no smooth transition between the pneumatic probe installation part and the probe part, there are step points on the shape such as edges or corners (such as Figure 5 As shown in the figure, and these shape step points are very close to the pressure measuring holes of the probe part, during the wind tunnel test, if the shape step points are directly exposed to the airflow, a turbulent area will be generated (such as Figure 6 As shown in the figure, the flow field stability around the pressure measuring holes of the probe is affected, which affects the test accuracy.

[0013] 2. Closed wind tunnel is the most common type of wind tunnel at home and abroad. This type of wind tunnel has a common feature that there is a slow-flowing air boundary layer on the surface of the tunnel wall near the test section. If the pneumatic probe only extends the probe part into the test section (such as Figure 7 ), the probe will be in the boundary layer. Since the boundary layer velocity is much smaller than the center velocity and the flow field is uneven, it does not meet the test requirements. During the test, the main test part of the test sample needs to avoid the boundary layer and be installed in the center area of ​​the test section (effective test area). If the installation part of the pneumatic probe is also extended into the test section (such as Figure 8 As shown in the figure, the step point of the pneumatic probe is also exposed to the airflow, forming a turbulent area, thus affecting the measurement accuracy of the detection part.

[0014] 3. Since there is no restriction on streamlines by the wall in the open wind tunnel, only a small area between the contraction section and the diffusion section is the effective test area that meets the flow field requirements. In order to place the probe part of the pneumatic probe in the effective test area of ​​the open test section, for the open wind tunnel of conventional size, there will also be turbulence problems caused by the shape step point (such as Fig. 9 shown). Summary of the invention

[0015] In view of the above-mentioned deficiencies in the prior art, the present invention provides a closed wind tunnel window test fixture for an engine pneumatic probe, which solves the problem that it is difficult to conduct a pneumatic consistency test of a pneumatic probe in a closed wind tunnel.

[0016] To achieve the above purpose, the technical solution adopted by the present invention is:

[0017] Provided is a closed wind tunnel window test fixture for an engine pneumatic probe, comprising a disc base, a disc surface of the disc base being fixedly connected to one end of a symmetrical wing-shaped support arm, the other end of the symmetrical wing-shaped support arm being fixedly connected to the outer side wall of a cylindrical fairing, a hole interconnected with each other and used for installing the pneumatic probe being arranged on the disc base, the symmetrical wing-shaped support arm and the cylindrical fairing, and the hole in the symmetrical wing-shaped support arm being a cavity hole matched with a mounting portion of the pneumatic probe, and a detection portion of the pneumatic probe passing through the hole on the cylindrical fairing and extending into the cylindrical fairing.

[0018] Furthermore, a truncated cone-shaped drainage hole is opened at the front port of the cylindrical fairing, the large diameter end of the drainage hole is connected to the front end outer edge of the cylindrical fairing to form an annular thin-edge tip, and the small diameter end of the drainage hole is smoothly connected to the inner annular surface of the cylindrical fairing.

[0019] Furthermore, the inclination angle of the conical surface of the drainage hole is 20 degrees.

[0020] Furthermore, the axial distance between the hole on the cylindrical fairing and the tip of the annular thin edge is not less than twice the length of the detection part of the pneumatic probe.

[0021] Furthermore, the inner wall shape of the cylindrical fairing is the same as the inner flow channel wall shape of the engine at the location where the pneumatic probe is installed.

[0022] Furthermore, the diameter of the cylindrical fairing is 3-4 times the length of the detection part of the pneumatic probe.

[0023] Furthermore, the axis of the cylindrical fairing is arranged parallel to the disk surface of the disk base, and the disk surface of the disk base is provided with engraved lines, and the engraved lines are arranged perpendicular to the axis of the cylindrical fairing.

[0024] Furthermore, the disc base is fixed to the test section rotating window interface by screws.

[0025] Furthermore, the length of the symmetrical wing-shaped support arm is determined according to the thickness of the boundary layer of the closed test section, and the difference between the length of the symmetrical wing-shaped support arm and the thickness of the boundary layer of the closed test section is not less than 5 cm.

[0026] The beneficial effects of the present invention are:

[0027] 1. This scheme simulates the internal flow path of the engine through a cylindrical fairing, and at the same time isolates the disturbance of the turbulence generated by the step point of the pneumatic probe shape on the pressure measuring hole of the pneumatic probe detection part; the front end of the cylindrical fairing is designed as a ring-shaped thin-edge tip, which can prevent the flow of the airflow from generating turbulence, thereby ensuring the flow field quality of the airflow in the cylindrical fairing.

[0028] 2. This scheme facilitates the installation of the pneumatic probe by setting up symmetrical wing-shaped arms, while keeping the detection part of the pneumatic probe away from the wind tunnel wall, thereby avoiding the influence of the boundary layer of the tunnel wall. In addition, the symmetrical wing-shaped arms have a rectifying effect on the airflow and will not cause excessive interference to the airflow.

[0029] 3. This solution can ensure the installation accuracy of the pneumatic probe and the cylindrical fairing angle by testing and correcting the angle of the scale line. For example, the plumb line method is used to ensure the verticality of the scale line, thereby ensuring the horizontality of the pneumatic probe and the cylindrical fairing. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the front view of the closed wind tunnel rotating window test fixture for the engine pneumatic probe.

[0031] Figure 2 This is a top view of the closed wind tunnel window test fixture for the engine pneumatic probe.

[0032] Figure 3 This is the left view of the closed wind tunnel window test fixture for the engine pneumatic probe.

[0033] Figure 4 A cross-sectional view of a cylindrical fairing.

[0034] Figure 5 This is a simplified diagram of the appearance of a pneumatic probe in the prior art.

[0035] Figure 6 Schematic diagram of the turbulence area at the step point of the pneumatic probe shape.

[0036] Figure 7 Schematic diagram of the installation of the pneumatic probe close to the wall of the closed wind tunnel test section.

[0037] Figure 8 Schematic diagram of the installation of the pneumatic probe in the effective test area of ​​a closed wind tunnel.

[0038] Fig. 9 Schematic diagram of an aerodynamic probe installed in a wind tunnel with a regular size opening.

[0039] Among them, 1. disc base, 2. symmetrical wing-shaped support arms, 3. cylindrical fairing, 301. annular thin-edge tip, 302. drainage hole, 303. smooth transition zone, 4. pneumatic probe, 5. engraved lines, 6. screws. DETAILED DESCRIPTION

[0040] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0041] like Figure 1 As shown, a closed wind tunnel rotating window test fixture for an engine pneumatic probe 4 is provided, which includes a disc base 1, a disc surface of the disc base 1 is fixedly connected to one end of a symmetrical wing-shaped support arm 2, and the other end of the symmetrical wing-shaped support arm 2 is fixedly connected to the outer wall of a cylindrical fairing 3, and a channel which is interconnected and used to install the pneumatic probe 4 is provided on the disc base 1, the symmetrical wing-shaped support arm 2 and the cylindrical fairing 3, and the channel located in the symmetrical wing-shaped support arm 2 is a cavity hole matched with the installation part of the pneumatic probe 4, and the detection part of the pneumatic probe 4 passes through the channel located on the cylindrical fairing 3 and extends into the cylindrical fairing 3.

[0042] As an optional implementation, the disc base 1 is fixed to the test section rotating window interface by screws 6, the axis of the cylindrical fairing 3 is arranged parallel to the disc surface of the disc base 1, and a scaled line 5 is arranged on the disc surface of the disc base 1, and the scaled line 5 is arranged perpendicular to the axis of the cylindrical fairing 3; this scheme can ensure the installation accuracy of the angle of the pneumatic probe 4 and the cylindrical fairing 3 by testing and correcting the angle of the scaled line 5, for example, using a plumb line to compare with the scaled line 5 on the disc base 1, and rotating the angle of the wind tunnel rotating window until the scaled line 5 is consistent with the direction of the plumb line, thereby ensuring the horizontality of the pneumatic probe 4 and the cylindrical fairing 3.

[0043] As an optional implementation, the length of the symmetrical wing-shaped support arm 2 is determined according to the thickness of the boundary layer of the closed test section, and the difference between the length of the symmetrical wing-shaped support arm 2 and the thickness of the boundary layer of the closed test section is not less than 5 cm; the detection part of the pneumatic probe 4 is positioned away from the wind tunnel wall to avoid being affected by the boundary layer of the tunnel wall, and the rectifying effect of the symmetrical wing-shaped support arm on the airflow will not cause excessive interference to the airflow.

[0044] As an optional embodiment, the inner wall shape of the cylindrical fairing 3 is the same as the shape of the internal flow channel wall of the engine at the installation position of the pneumatic probe 4. The cylindrical fairing 3 simulates the internal flow channel of the engine and isolates the disturbance of the turbulence generated by the step point of the pneumatic probe 4 on the pressure measuring hole of the detection part of the pneumatic probe 4; the diameter of the cylindrical fairing 3 is 3-4 times the length of the detection part of the pneumatic probe 4; a truncated cone-shaped drainage hole 302 is opened at the front end of the cylindrical fairing 3, and the inclination angle of the cone surface of the drainage hole 302 is The angle of the drainage hole 302 is 20 degrees; the large diameter end of the drainage hole 302 is connected to the front outer edge of the cylindrical fairing 3 and forms an annular thin-edge tip 301, which can prevent the airflow from generating turbulence; the axial distance between the channel on the cylindrical fairing 3 and the annular thin-edge tip 301 is not less than twice the length of the detection part of the pneumatic probe 4; the small diameter end of the drainage hole 302 is smoothly connected to the inner annular surface of the cylindrical fairing 3 to form a smooth transition zone 303, which ensures the stability of the airflow, thereby ensuring the flow field quality of the airflow in the cylindrical fairing 3.

Claims

1. A closed wind tunnel window test fixture for an engine pneumatic probe, characterized in that: The invention comprises a disc base (1), the disc surface of the disc base (1) is fixedly connected to one end of a symmetrical wing-shaped support arm (2), the other end of the symmetrical wing-shaped support arm (2) is fixedly connected to the outer wall of a cylindrical fairing (3), the disc base (1), the symmetrical wing-shaped support arm (2) and the cylindrical fairing (3) are provided with a hole which is interconnected and used for installing a pneumatic probe (4), and the hole in the symmetrical wing-shaped support arm (2) is a cavity hole which matches the installation part of the pneumatic probe (4), and the detection part of the pneumatic probe (4) passes through the hole in the cylindrical fairing (3) and extends into the cylindrical fairing (3).

2. The engine pneumatic probe closed wind tunnel rotating window test fixture according to claim 1, characterized in that: A truncated cone-shaped drainage hole (302) is provided at the front end of the cylindrical fairing (3); the large-diameter end of the drainage hole (302) is connected to the front outer edge of the cylindrical fairing (3) to form an annular thin-edge tip (301); and the small-diameter end of the drainage hole (302) is smoothly connected to the inner annular surface of the cylindrical fairing (3).

3. The engine pneumatic probe closed wind tunnel rotating window test fixture according to claim 2, characterized in that: The inclination angle of the conical surface of the drainage hole (302) is 20 degrees.

4. The closed wind tunnel window test fixture for the engine pneumatic probe according to claim 2 is characterized in that: The axial distance between the hole on the cylindrical fairing (3) and the annular thin edge tip (301) is not less than twice the length of the detection part of the pneumatic probe (4).

5. The closed wind tunnel window test fixture for the engine pneumatic probe according to claim 1, characterized in that: The shape of the inner wall of the cylindrical fairing (3) is the same as the shape of the inner flow channel wall of the engine at the position where the pneumatic probe (4) is installed.

6. The closed wind tunnel window test fixture for the engine pneumatic probe according to claim 1, characterized in that: The diameter of the cylindrical fairing (3) is 3-4 times the length of the detection part of the pneumatic probe (4).

7. The closed wind tunnel window test fixture for an engine pneumatic probe according to claim 1, characterized in that: The axis of the cylindrical fairing (3) is arranged parallel to the disk surface of the disk base (1), and the disk surface of the disk base (1) is provided with a scale line (5), and the scale line (5) is arranged perpendicular to the axis of the cylindrical fairing (3).

8. The closed wind tunnel window test fixture for an engine pneumatic probe according to claim 1, characterized in that: The disc base (1) is fixed to the test section rotating window interface by means of screws (6).

9. The closed wind tunnel window test fixture for an engine pneumatic probe according to claim 1, characterized in that: The length of the symmetrical wing-shaped support arm (2) is determined according to the thickness of the boundary layer of the closed test section, and the difference between the length of the symmetrical wing-shaped support arm (2) and the thickness of the boundary layer of the closed test section is not less than 5 cm.

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