Measuring device for total pressure loss of supersonic internal flow field

Abstract

The invention provides a device for measuring the total pressure loss of a supersonic internal flow field. The device comprises a total pressure probe, a supporting rod and a wind tunnel bottom plate, the total pressure probe is arranged on the wind tunnel bottom plate through a supporting rod. An airflow conveying channel is arranged in the total pressure probe, and a pressure measuring hole is formed in the central position of a wedge structure at the front end of the total pressure probe; an airflow outlet is formed in the rear end of the total pressure probe and connected with the pressure scanning valve through a hose. The total pressure and the Mach number do not need to be measured twice, the total pressure and the Mach number can be measured at the same time in single measurement, and compared with a traditional round probe, operability and measurement accuracy are achieved; compared with normal shock waves in front of a round probe, the oblique shock waves in front of the probe have smaller clogging degree on a flow field, and the influence of an intrusive device on flow field starting can be reduced; when the probes in array arrangement realize simultaneous measurement of multi-point total pressure, the oblique shock wave-oblique shock wave interference in front of the probes has very low influence on the measurement accuracy, and the accuracy of the result is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic flow measurement, and in particular to a measurement device for total pressure loss in a supersonic internal flow field. Background Art

[0002] Supersonic internal flow fields widely exist in scramjet engine inlets, isolators, and combustors. Their flows include characteristics such as shock / shock interference, shock / boundary layer interference, shock / jet interference, expansion waves, and shear layers, and have strong non-uniformity. For the entire flow channel, the total pressure recovery coefficients of the inlet and combustor can reflect the thrust loss and are important indicators for evaluating engine performance. Therefore, experimental measurements of the total pressure at the inlet and outlet of the inlet and combustor can extract key pressure data from the complex supersonic internal flow field, thereby enabling optimal design of the inlet profile, combustor structure, etc.

[0003] Existing technologies generally replace flow channels such as inlets and combustors with a wind tunnel test section and use wind tunnel experiments to diagnose and measure supersonic internal flow fields. For total pressure measurement, the most commonly used is a circular hollow pipe-shaped total pressure probe. When the wind tunnel incoming flow (if the Mach number is known) passes through it, a normal shock wave will be generated in front of the probe, and then it will drop to a subsonic airflow and enter the pipe for measurement. Through the total pressure of the airflow behind the wave and the relationship before and after the normal shock wave, the actual total pressure of the airflow at the probe can be inversely deduced. If the total pressure of the incoming flow is known, the Mach number of the incoming flow can also be inversely deduced. Therefore, this type of probe is also often used to calibrate the Mach number of the wind tunnel incoming flow. This traditional total pressure probe requires the known total pressure or Mach number during measurement to achieve the measurement or derivation of another parameter. However, for complex supersonic internal flow fields such as scramjet engine inlets and combustors, the Mach number and total pressure of their flows are unknown. Therefore, even if the total pressure behind the wave of the probe is known, the actual total pressure in front of the wave at the probe cannot be inversely deduced. In previous operation methods, two wind tunnel experiments are required. In the first experiment, a circular total pressure probe is used to measure the total pressure behind the normal shock wave; in the second experiment, the probe is removed, a ramp with a known angle is added at the probe position, the shock wave angle of the ramp is measured through a schlieren system, the Mach number at the probe position is deduced according to the oblique shock wave relationship, and finally the total pressure in front of the wave is inversely deduced according to the normal shock wave relationship.

[0004] Using the existing circular total pressure probe to measure the total pressure of a complex supersonic internal flow field requires two experiments to deduce the total pressure in front of the wave. On the one hand, the operation is cumbersome and the probe and ramp need to be repeatedly replaced. On the other hand, for transient flow fields, the existing technologies cannot achieve the simultaneous measurement of Mach number and total pressure and cannot measure the total pressure of the incoming flow. And when measuring the total pressure distribution of a certain cross-section, multiple probes need to be arranged in an array. Due to the detached normal shock wave in front of the probe, there will also be a problem of interference between the normal shock waves in front of the probes, which to a certain extent limits the experimental measurement accuracy of the cross-section total pressure distribution. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a measuring device for the total pressure loss of a supersonic internal flow field. The present invention can simultaneously measure the Mach number and the total pressure after the wave, and also reduce the shock interference phenomenon during the multi-point array arrangement of the probe, improving the measurement accuracy of the cross-sectional total pressure distribution.

[0006] The technical solution of the present invention is: a measuring device for the total pressure loss of a supersonic internal flow field, including a total pressure probe, a support rod and a wind tunnel bottom plate; the total pressure probe is arranged on the wind tunnel bottom plate through the support rod.

[0007] Preferably, an air flow conveying channel is arranged inside the total pressure probe. The front end of the total pressure probe is a wedge structure, and a pressure measuring hole is arranged at the central position of the wedge structure; an air flow outlet is arranged at the rear end of the total pressure probe, and the air flow outlet is connected to a pressure scanning valve through a hose.

[0008] Preferably, the included angle θ between the wedge structure and the horizontal plane is 20 degrees.

[0009] Preferably, the length and width of the pressure measuring hole are both 0.5 mm.

[0010] Preferably, the method for measuring the total pressure loss by using the total pressure probe is as follows:

[0011] S1), Assume that the Mach number and total pressure of the air flow at the most upstream of the total pressure probe are Ma1 and P 01 respectively; after passing through the oblique shock wave at the leading edge of the wedge, the flow Mach number and total pressure drop to Ma2 and P 02 respectively;

[0012] S2), After the air flow enters the probe, since the flow is still not supersonic at this time, a normal shock wave is generated inside the air flow conveying channel of the probe to reduce the flow to subsonic speed. The flow Mach number after the normal shock wave is Ma3 and P 03 ; the total pressure P 03 of the subsonic flow is collected and recorded by the pressure scanning valve, and the specific value of the total pressure P 03 of the subsonic flow after time-averaging processing;

[0013] S3), The total pressure after the wave measured by the total pressure probe is the total pressure after the two shock waves of the oblique shock wave and the normal shock wave, and the actual total pressure P 01 of the air flow before the wave at the probe is calculated through the shock wave angle β of the oblique shock wave.

[0014] Preferably, in step S3), P 01 and P 02 are obtained according to the total pressure relationship formulas before and after the normal shock wave and the oblique shock wave; that is:

[0015]

[0016] In the formula, β is the angle between the oblique shock wave and the horizontal plane, i.e., the shock wave angle; γ is a preset parameter.

[0017] Preferably, in step S3), the Mach numbers Ma1 and Ma2 are calculated by the following formula, i.e.:

[0018]

[0019]

[0020] In the formula, β is the angle between the oblique shock wave and the horizontal plane, i.e., the shock wave angle; γ is a preset parameter; θ is the angle between the wedge structure and the horizontal plane, and θ = 20°.

[0021] Preferably, the total pressure probes are arranged in a vertical array to measure the total pressure at multiple points simultaneously.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The present invention does not require separate measurements of the total pressure and the Mach number twice. In a single measurement, the simultaneous measurement of the total pressure and the Mach number can be achieved. Compared with the traditional circular probe, it has easy operability and measurement accuracy.

[0024] 2. Compared with the normal shock wave in front of the circular probe, the oblique shock wave in front of the probe in the present invention has a smaller blockage degree to the flow field, and can reduce the influence of the invasive device on the start of the flow field.

[0025] 3. When the present invention arranges the probes in an array to simultaneously measure the total pressure at multiple points, the influence of the oblique shock wave - oblique shock wave interference in front of the probe of the present invention on the measurement accuracy is very low, and the accuracy of the result is higher. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the measurement device of the present invention;

[0027] Figure 2 is a schematic diagram of the flow field structure of the total pressure probe of the present invention;

[0028] Figure 3 is a schematic diagram of the measurement process of the present invention;

[0029] In the figure, 1 - total pressure probe; 2 - support rod; 3 - wind tunnel bottom plate;

[0030] 11 - pressure measurement hole; 12 - air flow outlet. Detailed Embodiments

[0031] The following further describes the detailed embodiments of the present invention in conjunction with the drawings:

[0032] As shown Figure 1 In this embodiment, a measurement device for total pressure loss of a supersonic internal flow field is provided, including a total pressure probe 1, a support rod 2 and a wind tunnel bottom plate 3; the total pressure probe 1 is arranged on the wind tunnel bottom plate 3 through the support rod 2.

[0033] Preferably in this embodiment, an air flow delivery channel is arranged inside the total pressure probe 1. The front end of the total pressure probe 1 is a sharp wedge structure, and the sharp wedge structure is horizontally symmetrical. The angle θ between the sharp wedge structure and the horizontal plane is 20 degrees. And a pressure measurement hole 11 is arranged at the central position of the sharp wedge structure; in this embodiment, the length and width of the pressure measurement hole 11 are both 0.5 mm. An air flow outlet 12 is arranged at the rear end of the total pressure probe 1, and the air flow outlet 12 is connected to a pressure scanning valve through a hose.

[0034] Preferably in this embodiment, as shown Figure 2 and 3 shown, the method for measuring total pressure loss by using the total pressure probe 1 is as follows:

[0035] S1), Assume that the Mach number and total pressure at the most upstream of the total pressure probe 1 are Ma1 and P 01 respectively; after passing through the oblique shock wave at the leading edge of the sharp wedge, the flow Mach number and total pressure drop to Ma2 and P 02 respectively;

[0036] S2), After the air flow enters the total pressure probe 1, since the flow is still supersonic at this time, a normal shock wave is generated inside the air flow delivery channel of the total pressure probe 1 to reduce the flow to subsonic speed. The flow Mach number after the normal shock wave is Ma3 and P 03 ; the total pressure P 03 of the subsonic flow is collected and recorded by the pressure scanning valve, and the specific value of the total pressure P 03 of the subsonic flow after time-averaging processing;

[0037] S3), The total pressure after the wave measured by the total pressure probe 1 is the total pressure after the two shock waves of the oblique shock wave and the normal shock wave, and the actual total pressure P 01 of the air flow in front of the wave at the probe is calculated through the shock wave angle β of the oblique shock wave; specifically as follows:

[0038] In this embodiment, the Mach numbers Ma1 and Ma2 are calculated by the following formula, that is:

[0039]

[0040] In the formula, β is the angle between the oblique shock wave and the horizontal plane, that is, the shock wave angle; γ is a preset parameter. In this embodiment, γ = 1.4; θ is the angle θ = 20 degrees between the sharp wedge structure and the horizontal plane.

[0041] Then, according to the total pressure relationship formula before and after the normal shock wave and the oblique shock wave, P01 and P 02 That is:

[0042]

[0043] In the formula, β is the angle between the oblique shock wave and the horizontal plane, that is, the shock wave angle; γ is a preset parameter.

[0044] Preferably in this embodiment, by arranging the total pressure probe 1 in a vertical array to measure the total pressure at multiple points simultaneously.

[0045] The above embodiments and the descriptions in the specification only illustrate the principles and the best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A device for measuring total pressure loss in a supersonic flow field, characterized in that: It comprises a total pressure probe (1), a support rod (2) and a wind tunnel bottom plate (3); the total pressure probe (1) is arranged on the wind tunnel bottom plate (3) via the support rod (2); An air flow conveying channel is arranged inside the total pressure probe (1); the front end of the total pressure probe (1) is a wedge structure, and a pressure measuring hole (11) is arranged at the central position of the wedge structure; the rear end of the total pressure probe (1) is provided with an air flow outlet (12), and the air flow outlet (12) is connected to a pressure scanning valve through a hose.

2. The device for measuring total pressure loss in supersonic internal flow field according to claim 1, characterized in that: The method for measuring the total pressure loss using the total pressure probe (1) is as follows: S1), assuming that the Mach number and total pressure of the airflow at the most upstream of the total pressure probe (1) are Ma1 and P respectively. 01 ; After passing through the oblique shock wave at the leading edge of the wedge, the flow Mach number and total pressure drop are Ma2, P 02 ; S2), after the airflow enters the total pressure probe (1), since the flow is still not supersonic at this time, a positive shock wave is generated inside the airflow transmission channel of the total pressure probe (1), so that the flow is reduced to subsonic speed. The flow Mach number after the positive shock wave is Ma3, P 03 ; Subsonic flow total pressure P 03 The total pressure of subsonic flow after time-average processing is collected and recorded by the pressure scanning valve. 03 Specific value of S3) The total pressure after the wave measured by the total pressure probe (1) is the total pressure after the two shock waves, the oblique shock wave and the normal shock wave, and the actual total pressure of the airflow P in front of the wave at the probe is calculated by the shock angle β of the oblique shock wave. 01 .

3. The device for measuring total pressure loss of supersonic internal flow field according to claim 2, characterized in that: The Mach numbers Ma1 and Ma2 are calculated by the following formula: Where β is the angle between the oblique shock wave and the horizontal plane, that is, the shock wave angle; γ is a preset parameter, and θ is the angle between the wedge structure and the horizontal plane.

4. The device for measuring total pressure loss of supersonic internal flow field according to claim 3, characterized in that: According to the relationship between the total pressure before and after the normal shock wave and the oblique shock wave, P 01 and P 02 ;Right now: Where β is the angle between the oblique shock wave and the horizontal plane, that is, the shock wave angle; γ is a preset parameter.

5. The device for measuring total pressure loss of supersonic internal flow field according to claim 1, characterized in that: The wedge structure is horizontally symmetrical.

6. The device for measuring total pressure loss in supersonic internal flow field according to claim 3, characterized in that: The angle θ between the wedge structure and the horizontal plane is 20 degrees.

7. The device for measuring total pressure loss in supersonic internal flow field according to claim 1, characterized in that: The length and width of the pressure measuring hole (11) are both 0.5 mm.

8. The device for measuring total pressure loss of supersonic internal flow field according to claim 1, characterized in that: The total pressure probes (1) are arranged in a vertical array to measure the total pressure at multiple points simultaneously.

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