High-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure

Abstract

The invention relates to a spanwise-pressure-controllable high-speed three-dimensional internal flow tracer particle injection device which comprises N pressure regulating valves, an opening valve, a particle container and a power device, and N is larger than or equal to 3. The power device is connected with the particle container, the particle container is connected with the opening valve, the opening valve is connected with the N pressure regulating valves in parallel, and the N pressure regulating valves are uniformly arranged at the bottom of the internal flow model in the spanwise direction and uniformly spread tracer particles into the model through connecting interfaces on the internal flow model; wherein the power device reduces the pressure in the particle container through vacuumizing, so that the vacuum degree in the particle container meets the preset requirement; the particles are stored in the particle container, and after the vacuum degree in the particle container meets the preset requirement, the opening valve and the pressure regulating valve are opened, so that the particles enter the flowing space of the internal flow model from the particle injection position, and three-dimensional uniform scattering of the internal flow tracer particles of the aircraft is achieved.

Description

Technical Field

[0001] The present invention relates to a high-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure. During high-speed wind tunnel tests, the method can achieve three-dimensional uniform spreading of aircraft internal flow tracer particles, thereby creating prerequisites for high-speed internal flow particle image velocity field measurement, and belongs to the field of aerospace wind tunnel test technology. Background Art

[0002] Most of the air-breathing hypersonic vehicles represented by aerospace vehicles use combined engines, detonation engines, etc. as the main power. The air inlet and combustion chamber are the core of the air-breathing hypersonic propulsion system. The complex flow characteristics of the internal flow directly affect the performance of the propulsion system. Such aircraft often fly under variable angle of attack and sideslip angle. Under the flight conditions of variable angle of attack and sideslip angle, there are interferences of complex flow fields such as shock wave / shock wave and shock wave / boundary layer at the lip of the inlet, and even flow separation is caused, which seriously affects the aerodynamic performance of the inlet. When the separation bubble is large, it may also cause aerodynamic obstruction of the inlet, making the inlet unable to start. In-depth research and mastery of the complex flow characteristics of the internal flow are crucial for the integrated design of the airframe / propulsion, and can provide an important foundation for the performance improvement and innovative development of aircraft.

[0003] The use of particle image velocimetry to measure the velocity field of high-speed spatial flow fields is currently an effective technical means. However, in the measurement of high-speed internal flow, due to the strong compression and strong shear of the flow, there is a problem that tracer particles are difficult to enter the internal flow, especially when there are angles of attack and sideslip. The tracer particles entering the leeward area are very sparse, making it difficult to accurately calculate the velocity field of the internal flow. Therefore, it is necessary to supplement the internal flow with tracer particles.

[0004] However, internal flows such as intake ducts and combustion chambers present typical three-dimensional characteristics. Therefore, in order to ensure the uniformity of particle injection, it is necessary to accurately control the tracer particle injection pressure in each area within the spanwise range to ensure that the flow at the spanwise position is the same. Otherwise, it will greatly affect the calculation accuracy of the velocity field in three-dimensional space. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and provide a three-dimensional space tracer particle injection device and method with controllable spanwise pressure, so as to accurately control and realize high-speed inflow tracer particle injection and ensure the stability of spanwise injection.

[0006] The solution to the technical problem of the present invention is: a high-speed three-dimensional internal flow tracer particle injection device with controllable spanwise pressure, the device comprising N pressure regulating valves, an opening valve, a particle container, and a power device, where N is greater than or equal to 3;

[0007] The power device is connected to the particle container, the particle container is connected to the opening valve, the opening valve is connected in parallel to N pressure regulating valves, the N pressure regulating valves are evenly arranged at the bottom of the internal flow model along the span direction, and the tracer particles are evenly spread into the model through the connection interfaces on the internal flow model respectively;

[0008] The power device reduces the pressure in the particle container by vacuuming so that the vacuum degree in the particle container meets the preset requirements;

[0009] The particles are stored in a particle container. When the vacuum degree in the particle container meets the preset requirements, the opening valve and the pressure regulating valve are opened to allow the particles to enter the flow space of the internal flow model from the particle injection position to achieve three-dimensional uniform spreading of the aircraft internal flow tracer particles.

[0010] Preferably, the output end of the pressure regulating valve is connected to a corresponding connection interface on the internal flow model through a standard quick-connect connector.

[0011] Another technical solution of the present invention is: a high-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure, the method comprising the following steps:

[0012] S1. According to the incoming flow conditions of the particle image velocimetry test, the spanwise flow field pressure distribution of the flow space of the internal flow model is simulated and calculated by a numerical simulation method, and the flow field pressure P3(y) at the injection position of the tracer particles is preliminarily obtained, where y represents the spanwise position of the tracer particle injection position;

[0013] S2, adjusting the pressure value P6 in the particle container by the control power device, so that the particle flow pressure P5 before the pressure regulating valve is greater than the flow field pressure P3 (y) at the injection position of the tracer particles, and is within a preset range, and then entering step S3;

[0014] S3, opening the opening valve to connect the particle container and the pressure regulating valve, and adjusting the pressure regulating valves at the tracer particle injection positions respectively so that the pressure after the pressure regulating valves corresponding to the tracer particle injection positions meets the preset conditions.

[0015] Preferably, the preset range in step S2 is:

[0016] 1.2P3(y) max <P5<1.4P3(y) max

[0017] Among them, P3(y) max is the maximum value of the spanwise pressure distribution P3(y) at the tracer particle injection position obtained by simulation.

[0018] Preferably, the preset condition in step S3 is:

[0019] P3(y) <P4≤1.05P3(y)。

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

[0021] (1) The present invention realizes the spreading of tracer particles in the inner flow space by means of a local particle injection method. Compared with the existing method of only mainstream spreading, it effectively supplements the concentration of the inner flow tracer particles, making it possible to calculate the spatial velocity field using the PIV method.

[0022] (2) The present invention uses an intermittent spanwise distributed injection method to individually adjust the pressure distribution at each spanwise position, thereby ensuring the uniformity of particle spreading in the entire three-dimensional space. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a model of an embodiment of the present invention and a position for injecting tracer particles;

[0024] Figure 2 It is a schematic diagram of a spanwise injection control device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail step by step in conjunction with the accompanying drawings.

[0026] according to Figure 1 and Figure 2 The schematic diagram of the device is connected to form an overall spanwise pressure-controllable three-dimensional space tracer particle injection device; Figure 1 Schematic diagram of the model and the injection position of tracer particles; Figure 2 Schematic diagram of particle control method with controllable spanwise pressure.

[0027] like Figure 1 and Figure 2 As shown, a high-speed three-dimensional internal flow tracer particle injection device with controllable spanwise pressure provided by the present invention includes N pressure regulating valves 4, an opening valve 5, a particle container 6, and a power device 7, where N is greater than or equal to 3; in this embodiment, N is 4.

[0028] The power device 7 is connected to the particle container 6, the particle container 6 is connected to the opening valve 5, the opening valve 5 is connected in parallel to N pressure regulating valves 4, and the N pressure regulating valves 4 are evenly arranged at the bottom 2 of the internal flow model along the span direction, and the tracer particles are evenly spread into the interior of the model through the connection interfaces on the internal flow model respectively;

[0029] The power device 7 reduces the pressure in the particle container 6 by vacuuming, so that the vacuum degree in the particle container 6 meets the preset requirements;

[0030] The particles are stored in the particle container 6. After the vacuum degree in the particle container 6 meets the preset requirements, the opening valve 5 and the pressure regulating valve 4 are opened to allow the particles to enter the flow space 1 of the internal flow model from the particle injection position 2 to achieve three-dimensional uniform spreading of the aircraft internal flow tracer particles.

[0031] The output end of the pressure regulating valve 4 is connected to the corresponding connection interface on the internal flow model through a standard quick-connect connector.

[0032] The present invention also provides a high-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure, the method comprising the following steps:

[0033] S1. According to the incoming flow conditions of the particle image velocimetry test, the spanwise flow field pressure distribution of the flow space 1 of the internal flow model is simulated and calculated by a numerical simulation method, and the flow field pressure P3(y) at the tracer particle injection position 3 is preliminarily obtained, where y represents the spanwise position of the tracer particle injection position 3;

[0034] S2, considering the possible pressure loss caused by the pressure pipe and valve, the control power device 7 adjusts the pressure value P6 in the particle container 6, so that the particle flow pressure P5 before the pressure regulating valve 4 is greater than the flow field pressure P3 (y) at the tracer particle injection position 3, and is within the preset range, and then enters step S3;

[0035] The preset ranges are:

[0036] 1.2P3(y) max <P5<1.4P3(y) max

[0037] Among them, P3(y) max is the maximum value of the spanwise pressure distribution P3(y) at the tracer particle injection position (3) obtained by simulation.

[0038] S3, open the opening valve 5 to connect the particle container 6 and the pressure regulating valve 4, and adjust the pressure regulating valve 4 at the tracer particle injection position 3 respectively, so that the pressure after the pressure regulating valve 4 corresponding to the tracer particle injection position 3 meets the preset conditions, and try to ensure that P4 is close to P3 (y);

[0039] The default conditions are:

[0040] P3(y) <P4≤1.05P3(y)。

[0041] Considering the possible pressure loss in the injection pipeline, the tracer particle dispersion in the spanwise plane is further measured by particle image velocimetry to observe the flow field at the particle injection position. If an obvious strong shock wave appears, it indicates that the particle injection velocity is too fast, which has a great impact on the flow field, and P4 needs to be reduced; if no particles are injected into the flow field, the value of P4 is increased so that the final tracer particles "slowly" enter the internal flow field of the model.

[0042] Based on the captured particle images, a 16 pixel × 16 pixel window can be selected at the outlet position to calculate the number of tracer particles within the window. The appropriate number of particles n within this window should satisfy 8 < n < 20. If the number of tracer particles is less than 5, it indicates that the injected particle quantity is small, and the value of P4 needs to be increased by adjusting the pressure valve (4) to increase the number of particles entering the flow field; if the number of particles is greater than 20, it means that too many particles are injected, and the value of P4 needs to be reduced until the number of particles is within the ideal range.

[0043] By this method, the replenishment of tracer particles for high-speed internal flow can be achieved, and at the same time, the interference of tracer particle injection on the flow field can be avoided to the greatest extent, so as to realize the high-precision velocity field measurement of high-speed internal flow.

[0044] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the disclosed methods and technical contents without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention all belong to the protection scope of the technical solution of the present invention.

Claims

1. A high-speed three-dimensional internal flow tracer particle injection device with controllable spanwise pressure, characterized in that It comprises N pressure regulating valves (4), an opening valve (5), a particle container (6), and a power device (7), where N is greater than or equal to 3; The power device (7) is connected to the particle container (6), the particle container (6) is connected to the opening valve (5), the opening valve (5) is connected in parallel to N pressure regulating valves (4), the N pressure regulating valves (4) are evenly arranged at the bottom of the internal flow model along the span direction, and the tracer particles are evenly spread into the interior of the model through the connection interfaces on the internal flow model respectively; The power device (7) reduces the pressure in the particle container (6) by evacuating the particle container, so that the vacuum degree in the particle container (6) meets the preset requirements; The particles are stored in a particle container (6). After the vacuum degree in the particle container (6) meets preset requirements, the opening valve (5) and the pressure regulating valve (4) are opened, so that the particles enter the flow space (1) of the internal flow model from the particle injection position (2) to achieve three-dimensional uniform spreading of the aircraft internal flow tracer particles.

2. The high-speed three-dimensional internal flow tracer particle injection device with controllable spanwise pressure according to claim 1, characterized in that: The output end of the pressure regulating valve (4) is connected to the corresponding connection interface on the internal flow model through a standard quick-connect connector.

3. A high-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure, characterized in that The steps include: S1. According to the incoming flow conditions of the particle image velocimetry test, the spanwise flow field pressure distribution of the flow space (1) of the internal flow model is simulated and calculated by a numerical simulation method, and the flow field pressure P3(y) at the tracer particle injection position (3) is preliminarily obtained, where y represents the spanwise position of the tracer particle injection position (3); S2, adjusting the pressure value P6 in the particle container (6) by the control power device (7) so that the particle flow pressure P5 in front of the pressure regulating valve (4) is greater than the flow field pressure P3 (y) at the tracer particle injection position (3) and is within a preset range, and then entering step S3; S3, opening the opening valve (5) so that the particle container (6) and the pressure regulating valve (4) are connected, and respectively adjusting the pressure regulating valve (4) at the tracer particle injection position (3) so that the pressure after the pressure regulating valve (4) corresponding to the tracer particle injection position (3) meets the preset conditions.

4. A high-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure according to claim 1, characterized in that: The preset range in step S2 is: 1.2P3(y) max <P5<1.4P3(y) max Among them, P3(y) max is the maximum value of the spanwise pressure distribution P3(y) at the tracer particle injection position (3) obtained by simulation.

5. A high-speed three-dimensional internal flow tracer particle injection method with controllable spanwise pressure according to claim 1, characterized in that: The preset conditions in step S3 are: P3(y) <P4≤1.05P3(y)。

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