Method and system for judging pointed cone transition position based on second modal wave amplitude

Abstract

A method for judging a pointed cone transition position based on a second modal wave amplitude comprises the following steps: carrying out a pointed cone boundary layer stability test in a hypersonic wind tunnel, and capturing a second modal wave; and judging the transition position and the surface flow state distribution of the pointed cone model by comparing the amplitudes of the second modal waves at different flow direction positions. Compared with a traditional transition position measurement method, the method provided by the invention can obtain the high-frequency pulsation information of the pointed cone surface while measuring the transition position. The method provided by the invention is convenient and rapid, the second modal wave frequency and the model surface transition position can be obtained at the same time, and a method is provided for improving the transition measurement capability of the hypersonic wind tunnel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind tunnel test measurement, and particularly relates to a method and system for determining the transition position of a sharp cone based on the amplitude of the second mode in stability wave. BACKGROUND

[0002] The transition problem is a problem that cannot be ignored in the design of a hypersonic vehicle. The increase in friction and heat flow caused by the transition directly affects the aerodynamic characteristics of the hypersonic vehicle. At present, the boundary layer transition caused by high-frequency disturbance is more recognized in the transition field, so in order to study the boundary layer transition, the high-frequency disturbance quantity must be measured, and the second mode wave is the main mode of the transition in hypersonic flow.

[0003] The mature method for measuring the second mode wave is to use a high-frequency pulsating pressure sensor to measure. However, in order to measure the second mode wave frequency and also want to obtain the transition position of the model surface, a heat flow sensor is usually additionally arranged near the high-frequency pulsating pressure sensor, and the transition position is determined by observing the heat flow change along the flow direction. However, this method not only increases the types of sensors and the measurement system, but also may affect the measurement and collection of the high-frequency pulsating pressure sensor near the heat flow sensor. SUMMARY

[0004] The technical purpose of the present application is to provide a method and system for determining the transition position of a sharp cone based on the amplitude of the second mode wave. By comparing the amplitude of the second mode wave at different flow direction positions, the transition position of the sharp cone model and the surface flow state distribution can be determined. Compared with the traditional transition position measurement method, the method of the present application can measure the transition position while obtaining the high-frequency pulsating information of the sharp cone surface.

[0005] To achieve the above technical purpose, the present application adopts the following technical solution: a method for determining the transition position of a sharp cone based on the amplitude of the second mode wave, comprising:

[0006] Performing a sharp cone boundary layer stability test in a hypersonic wind tunnel to capture the second mode wave;

[0007] By comparing the amplitude of the second mode wave at different flow direction positions, the transition position of the sharp cone model and the surface flow state distribution can be determined.

[0008] Further, the sharp cone boundary layer stability test in the hypersonic wind tunnel to capture the second mode wave comprises:

[0009] The sharp cone is used as a test model, a plurality of PCB high-frequency pulsating pressure sensors are arranged on the same generatrix of the surface of the sharp cone model, and a collection system capable of high-frequency collection and low-noise interference is built; the collection system is used to obtain the pulsating pressure-time curves of different sensor measuring points during the sharp cone boundary layer stability test in the hypersonic wind tunnel; and the second modal wave is obtained after Fourier transform.

[0010] Further, the transition starting position refers to the position of the maximum amplitude of the second modal wave.

[0011] Further, the hypersonic wind tunnel is a Φ1m caliber hypersonic shock wave wind tunnel, and the running time of the wind tunnel is about 5ms-60ms.

[0012] Further, the half-cone angle of the sharp cone model is 7°, the total length is 1000mm, and the material is 30CrMnSiA.

[0013] Further, the diameter of the PCB high-frequency pulsating pressure sensor is 3.18mm, the length is 7.6mm, the range is 345kPa, the accuracy is 7Pa, and the maximum range is 1MHz.

[0014] Further, the collection system comprises a high-frequency signal collector, a signal conditioner and a shielded cable, the high-frequency signal collector adopts an NIPXI-5922 collection card to collect the information of the PCB pressure sensor; the signal conditioner realizes the power excitation and voltage signal digital-analog conversion of the PCB pressure sensor, the signal conditioner comprises a 4-channel ICP amplification conditioning module, the output range is ±10V, and the frequency response is greater than 1MHz; and the high-frequency signal collector and the signal conditioner are connected by the shielded cable.

[0015] A system for determining the transition position of a sharp cone based on the amplitude of a second modal wave, comprising a PCB high-frequency pulsating pressure sensor, a sharp cone model, a collection system and a data processing module.

[0016] A plurality of PCB high-frequency pulsating pressure sensors are arranged on the same generatrix of the surface of the sharp cone model.

[0017] The collection system is used to collect the pulsating pressure-time curves of different sensor measuring points on the surface of the sharp cone model during the sharp cone boundary layer stability test in the hypersonic wind tunnel.

[0018] The data processing module obtains the second modal wave after Fourier transform of the pulsating pressure-time curves, and determines the transition position of the sharp cone model and the surface flow state distribution by comparing the amplitudes of the second modal waves at different flow directions.

[0019] Compared with the prior art, the advantages of the present application are that:

[0020] (1) The method for determining the sharp cone transition position based on the second modal wave amplitude can measure the transition position and obtain the sharp cone surface high-frequency fluctuation information at the same time.

[0021] (2) The method for determining the sharp cone transition position based on the second modal wave amplitude can save the installation of heat flow sensors and their acquisition systems compared with the traditional measurement method. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.

[0023] Figure 1 is a sharp cone model diagram and a measurement point layout diagram;

[0024] Figure 2 is a fluctuating pressure power spectrum diagram of different measurement points;

[0025] Figure 3 is a flowchart of the method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0026] The present application is described in conjunction with the drawings.

[0027] A method for determining the sharp cone transition position based on the second modal wave amplitude, comprising the following steps:

[0028] 1) A sharp cone boundary layer stability test is performed in a hypersonic wind tunnel, and a PCB high-frequency fluctuating pressure sensor is used to capture the second modal wave;

[0029] 2) By comparing the amplitude of the second modal wave at different flow direction positions, the transition position of the sharp cone model and the surface flow state distribution can be determined.

[0030] A sharp cone boundary layer stability test is performed in a hypersonic wind tunnel, and a PCB high-frequency fluctuating pressure sensor is used to capture the second modal wave, comprising:

[0031] During the hypersonic wind tunnel test, a sharp cone is used as a test model, a plurality of high-frequency fluctuating pressure sensors are arranged on the same generatrix of the model surface, and a set of acquisition system capable of high-frequency acquisition and low-noise interference is built. The acquisition system can obtain the fluctuating pressure of different measurement points with time, and the second modal wave can be obtained after Fourier transform.

[0032] By comparing the amplitude of the second modal wave at different flow direction positions, the transition position of the sharp cone model and the surface flow state distribution can be determined, comprising:

[0033] Because the amplitude of the second modal wave gradually increases and then decreases in the process of the flow state from laminar flow to transition and then to turbulent flow on the surface of the sharp cone model. When the sharp cone boundary layer is about to transition, the amplitude of the second modal wave continuously increases, and the frequency of the second modal wave gradually decreases; when the amplitude of the second modal wave reaches the maximum, the boundary layer begins to transition, that is, the position of the maximum amplitude of the second modal wave is the position of the transition initiation. If the second modal wave exists on the surface of the sharp cone model, when the amplitude of the second modal wave gradually increases along the flow direction until the bottom of the model, it indicates that the flow state on the surface of the sharp cone model is pure laminar flow; when the amplitude of the second modal wave gradually increases and then decreases along the flow direction, it indicates that the flow state on the surface of the sharp cone model is coexistence of laminar flow and transition; when the amplitude of the second modal wave gradually decreases along the flow direction until the second modal wave disappears, it indicates that the flow state on the surface of the sharp cone model is coexistence of transition and turbulent flow.

[0034] The hypersonic wind tunnel in step 1) is a Φ1m caliber hypersonic shock tunnel, and the running time of the wind tunnel is about 5ms-60ms.

[0035] The half-cone angle of the sharp cone model in step 1) is 7°, the total length is 1000mm, and the material is 30CrMnSiA.

[0036] The diameter of the PCB high-frequency pulsating pressure sensor in step 1) is 3.18mm, the length is 7.6mm, the range is 345kPa, the accuracy is 7Pa, and the maximum range is 1MHz.

[0037] A system for determining the transition position of a sharp cone based on the amplitude of the second modal wave, comprising a PCB high-frequency pulsating pressure sensor, a sharp cone model, a collection system and a data processing module.

[0038] A plurality of PCB high-frequency pulsating pressure sensors are arranged on the same generatrix on the surface of the sharp cone model.

[0039] The collection system is used to collect the pulsating pressure-time curve of different sensor measuring points on the surface of the sharp cone model during the sharp cone boundary layer stability test in the hypersonic wind tunnel; the collection system comprises a high-frequency signal collector, a signal conditioner and a shielded cable and the like modules, wherein the collector adopts an NIPXI-5922 collection card (with a maximum sampling frequency of 15MHz), the signal conditioner can realize power excitation and voltage signal digital-analog conversion of the PCB high-frequency pulsating pressure sensor (including a 4-channel ICP amplification conditioning module, with an output range of ±10V and a frequency response of greater than 1MHz), the high-frequency signal collector and the signal conditioner are connected by a shielded cable, and the shielded cable can reduce external noise interference;

[0040] The data processing module obtains the second modal wave after Fourier transform of the pulsating pressure-time curve, and determines the transition position of the sharp cone model and the flow state distribution on the surface of the sharp cone model by comparing the amplitudes of the second modal waves at different flow direction positions.

[0041] Embodiments:

[0042] A method for determining the transition position of a sharp cone based on the amplitude of the second modal wave, comprising the following steps:

[0043] 1. In the hypersonic wind tunnel test, a sharp cone is used as the test model, a plurality of high-frequency fluctuating pressure sensors (as shown in Figure 1 ) are arranged on the same generatrix on the surface of the model, and a collection system capable of high-frequency collection and low-noise interference is built. The fluctuating pressure of different measuring points with time can be obtained through the collection system, and the second modal wave can be obtained after Fourier transform. The hypersonic wind tunnel is a Φ1m caliber hypersonic shock tunnel, and the running time of the wind tunnel is about 5ms-60ms. The half-cone angle of the sharp cone model is 7°, the total length is 1000mm, and the material is 30CrMnSiA. The diameter of the PCB high-frequency fluctuating pressure sensor is 3.18mm, the length is 7.6mm, the range is 345kPa, the accuracy is 7Pa, and the maximum range is 1MHz.

[0044] 2. Because on the surface of the sharp cone model, the amplitude of the second modal wave gradually increases and then decreases (as shown in Figure 2 ) in the process of flow state from laminar flow to transition and then to turbulent flow. When the sharp cone boundary layer is about to transition, the amplitude of the second modal wave increases continuously, and the frequency of the second modal wave gradually decreases; when the amplitude of the second modal wave reaches the maximum, the boundary layer begins to transition, that is, the position of the maximum amplitude of the second modal wave is the position of the transition start (PCB3) (as shown in Table 1 below).

[0045] Table 1 Frequency corresponding to maximum amplitude of different PCB measuring points

[0046] Measurement point number 1 2 3 4 5 6 7 8 F (KHz) 183.71 158.05 151.9 141.46 134.90 115.14 115.14 104.70 PCB (Pa2 / Hz) 0.0918 0.4613 1.0249 1.0265 0.5542 0.6482 0.7493 0.2240

[0047] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

[0048] The contents not described in detail in the specification of the present application are the known technology of those skilled in the art.

Claims

1. A method for determining the transition position of a pointed cone based on the amplitude of the second mode wave, characterized in that: include: Conducting cone boundary layer stability tests in a hypersonic wind tunnel to capture the second mode wave; By comparing the amplitudes of the second mode waves at different flow directions, the transition position and surface flow distribution of the pointed cone model can be determined.

2. The method for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 1, wherein: Conducting cone boundary layer stability tests in a hypersonic wind tunnel to capture the second mode wave, including: A pointed cone is used as the test model. Several PCB high-frequency pulsating pressure sensors are arranged on the same busbar on the surface of the pointed cone model, and an acquisition system capable of high-frequency acquisition and low noise interference is built. The time-varying curves of the pulsating pressure at different sensor measuring points are obtained through the acquisition system, and the second mode wave is obtained after Fourier transform.

3. The method for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 1, wherein: The transition starting position refers to the position where the second modal wave amplitude is the largest.

4. The method for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 1, wherein: The hypersonic wind tunnel is a Φ1m caliber hypersonic shock wave wind tunnel, and the operation time of the wind tunnel is about 5ms-60ms.

5. The method for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 1, wherein: The semi-cone angle of the pointed cone model is 7°, the total length is 1000 mm, and the material is 30CrMnSiA.

6. The method for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 1, wherein: The PCB high-frequency pulsation pressure sensor has a diameter of 3.18 mm, a length of 7.6 mm, a measuring range of 345 kPa, an accuracy of 7 Pa, and a maximum measuring range of 1 MHz.

7. The method for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 6, characterized in that: The acquisition system includes a high-frequency signal collector, a signal conditioner and a shielded cable. The high-frequency signal collector uses a NIPXI-5922 acquisition card to collect information from the PCB pressure sensor. The signal conditioner realizes the power excitation and voltage signal digital-to-analog conversion of the PCB pressure sensor. The signal conditioner includes a 4-channel ICP amplification and conditioning module with an output range of ±10V and a frequency response greater than 1MHz. The high-frequency signal collector and signal conditioner are connected by a shielded cable.

8. A system for determining the transition position of a pointed cone based on the amplitude of the second mode wave, characterized in that: It includes PCB high-frequency pulsation pressure sensor, cone model, acquisition system and data processing module; Several PCB high-frequency pulsation pressure sensors are arranged on the same busbar on the surface of the pointed cone model; The acquisition system is used to obtain the curve of the pulsating pressure variation over time at different sensor measuring points on the surface of the cone model during the cone boundary layer stability test in the hypersonic wind tunnel; The data processing module performs Fourier transform on the curve of the pulsating pressure changing with time to obtain the second mode wave. By comparing the amplitudes of the second mode waves at different flow directions, the transition position and surface flow distribution of the pointed cone model are determined.

9. The system for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 8, characterized in that: The acquisition system includes a high-frequency signal collector, a signal conditioner and a shielded cable. The high-frequency signal collector uses a NIPXI-5922 acquisition card to collect information from the PCB pressure sensor. The signal conditioner realizes the power excitation and voltage signal digital-to-analog conversion of the PCB pressure sensor. The signal conditioner includes a 4-channel ICP amplification and conditioning module with an output range of ±10V and a frequency response greater than 1MHz. The high-frequency signal collector and signal conditioner are connected by a shielded cable.

10. The system for determining the transition position of a pointed cone based on the second modal wave amplitude according to claim 9, characterized in that: The PCB high-frequency pulsation pressure sensor has a diameter of 3.18 mm, a length of 7.6 mm, a measuring range of 345 kPa, an accuracy of 7 Pa, and a maximum measuring range of 1 MHz.

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