CN-121994444-A - Carbon dioxide injection device for tracing phase-change flow field of conventional hypersonic wind tunnel

CN121994444ACN 121994444 ACN121994444 ACN 121994444ACN-121994444-A

Abstract

The invention relates to the technical field of hypersonic wind tunnel tests, in particular to a carbon dioxide injection device for tracing a phase-change flow field of a conventional hypersonic wind tunnel, which comprises a gas supply module, a flow regulation module, an injection mixing module, an image feedback module and a control module, wherein the gas supply module is used for supplying carbon dioxide gas, the flow regulation module is used for regulating and controlling output flow of the carbon dioxide gas, the injection mixing module comprises an injection port and a wind tunnel heater, the injection port is positioned at the front end of the wind tunnel heater, an hypersonic wind tunnel test section, an outlet of the wind tunnel heater sprays mixed gas to the hypersonic wind tunnel test section through a spray pipe, the image feedback module is used for collecting Rayleigh scattering images in the hypersonic wind tunnel test section and analyzing quality indexes of the Rayleigh scattering images, and the control module is used for dynamically regulating the flow regulation module based on deviation of the quality indexes and set values. The invention can realize the control of the carbon dioxide flow in a wide range and high precision, and can obtain the high-quality flow field display effect under different wind tunnel running states through the feedback regulation and control with the image feedback module.

Inventors

WANG HONGWEI
HUANG ZHAN
LI XIAOHUI
LIU YAOFENG
QU ZHENLE
REN SHAOJIE

Assignees

中国航天空气动力技术研究院

Dates

Publication Date: 20260508
Application Date: 20251229

Claims (10)

1. A carbon dioxide injection device for conventional hypersonic wind tunnel phase change flow field tracing, comprising: a gas supply module including a carbon dioxide gas cylinder module for supplying carbon dioxide gas; The flow regulation and control module is connected with the outlet of the gas supply module and used for regulating and controlling the output flow of the carbon dioxide gas; The injection mixing module comprises an injection port and a wind tunnel heater, wherein the injection port is connected with the outlet of the flow regulating module, and is positioned at the front end of the wind tunnel heater to ensure that carbon dioxide gas is fully mixed with the main flow as incoming flow; The hypersonic wind tunnel test section, the outlet of the wind tunnel heater sprays mixed gas to the hypersonic wind tunnel test section through a spray pipe; The image feedback module comprises an image acquisition unit and an image processing unit, wherein the image acquisition unit is used for acquiring Rayleigh scattering images in a hypersonic wind tunnel test section, the image processing unit is used for analyzing quality indexes of the Rayleigh scattering images, and the image acquisition unit is connected with the image processing unit; And the control module is used for dynamically adjusting the flow regulation module based on the deviation between the quality index and a set value, and is connected with the image feedback module and the flow regulation module.
2. The carbon dioxide injection device of claim 1, wherein the gas supply module comprises a plurality of carbon dioxide gas cylinder modules connected in series, each carbon dioxide gas cylinder module comprising a plurality of cylinders connected in parallel.
3. The carbon dioxide injection device of claim 1, wherein the flow control module comprises a main control section and a sub control section which are sequentially connected, the inlet of the main control section is connected with the outlet of the gas supply module, the sub control section comprises a large flow branch and a small flow branch which are arranged in parallel, and the outlets of the main control section and the sub control section are connected with the injection port through pipelines.
4. The carbon dioxide injection device of claim 3, wherein the main control section is provided with a main control stop valve, a main filter, a flow regulating valve, a coriolis mass flowmeter and a pressure sensor in sequence; The high-flow branch is sequentially provided with a first electromagnetic control valve, a first check valve, a first filter and a first regulation and control pore plate, and the low-flow branch is sequentially provided with a second electromagnetic control valve, a second check valve, a second filter and a second regulation and control pore plate.
5. The carbon dioxide injection device of claim 1, wherein the injection port is located 2-3 meters in front of the wind tunnel heater.
6. The carbon dioxide injection device of claim 1, wherein the injection port injection pressure is 0.1-0.3MPa greater than a tunnel stabilizing section pressure in the hypersonic tunnel test section.
7. The carbon dioxide injection device of claim 1, wherein the main flow mass flow of the wind tunnel in the hypersonic wind tunnel test section The estimation formula is as follows: (1); Wherein, the As a specific heat ratio function, the calculation formula is as follows: (2); for the specific heat ratio of the gas, 1.4 is generally taken, In order for the total pressure of the incoming flow, R is the gas constant, generally 287J/(kg.K), To total temperature of incoming flow.
8. The carbon dioxide injection device of claim 7, wherein the nozzle throat area is calculated by the formula: (3); Wherein, the For the outlet area of the spray pipe, For the nozzle outlet mach number, Is the diameter of the outlet of the spray pipe.
9. The carbon dioxide injection device of claim 1, wherein the quality metrics of the rayleigh scattering image include image signal-to-noise ratio, contrast, and uniformity.
10. The carbon dioxide injection device of claim 9, wherein analyzing the image signal-to-noise ratio SNR of the rayleigh scattering image comprises: Defining the image signal-to-noise ratio SNR as: (4); Wherein, the The average intensity of the signal image area is obtained in real time through image acquisition by using an image gray scale meter, The average intensity of the noise image is obtained by running the system before the test.

Description

Carbon dioxide injection device for tracing phase-change flow field of conventional hypersonic wind tunnel Technical Field The invention relates to the technical field of hypersonic wind tunnel tests, in particular to a carbon dioxide injection device for tracing a phase-change flow field of a conventional hypersonic wind tunnel. Background Hypersonic ground test equipment is an important platform for researching aerodynamic characteristics of an aircraft, and a conventional hypersonic wind tunnel bears a large number of engineering test tasks due to the capability of long-term operation, quick implementation and high redundancy operation. However, such wind tunnels typically sacrifice low noise flow field characteristics in exchange for the engineering advantages described above, resulting in relatively low flow field quality, which is generally considered difficult to conduct in a fine flow structure observation-related basis study. The carbon dioxide phase change tracing technology is an economic, pollution-free and excellent-display-effect non-contact flow field visualization method. The principle is that carbon dioxide gas undergoes phase change due to rapid temperature drop in the process of fluid expansion in the following spray pipe, and is condensed into nano-scale ice crystal particles, and the particles generate Rayleigh scattering on laser, so that the visualization of a convection field structure is realized. Studies show that in the CO 2/N2 mixed gas, high-quality flow velocity measurement and flow visualization effects can be obtained only by 1% of CO 2 concentration. The technology is successfully applied to multi-research wind tunnels and college mute wind tunnels, and provides important data support for hypersonic flow research. However, the application of carbon dioxide phase change tracking technology in large caliber conventional hypersonic wind tunnels in engineering units still faces many challenges: The flow requirement range is wide, namely, for a large-caliber wind tunnel with the magnitude of 500mm or 1000mm, the carbon dioxide injection flow needs to cover a wide range of 20-400g/s to adapt to the requirements of different test states; The control precision requirement is high, namely the carbon dioxide flow needs to be accurately controlled, the excessive flow can cause flow interference, and the insufficient tracing effect is poor; the difficulty of mixing with the main flow is great, namely, how to ensure the uniform mixing of the carbon dioxide and the main flow in the large-caliber wind tunnel is a great difficulty; The prior art lacks the ability to dynamically adjust injection flow according to actual tracer effect. Especially for the conventional hypersonic wind tunnel, the difficulty of carbon dioxide phase change tracing technology application is increased due to the characteristic of larger flow field noise. Although Computational Fluid Dynamics (CFD) simulation can predict the condensing behavior of supercritical carbon dioxide in converging-diverging nozzles, how to achieve stable and reliable carbon dioxide injection and phase change tracking in practical large wind tunnels still requires specially designed injection devices and control strategies. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a carbon dioxide injection device for tracing a phase-change flow field of a conventional hypersonic wind tunnel, which can realize wide-range and high-precision carbon dioxide flow control, and can obtain high-quality flow field display effects under different wind tunnel running states through feedback regulation and control with an image feedback module. One or more embodiments of the present specification provide a carbon dioxide injection device for conventional hypersonic wind tunnel phase change flow field tracing, comprising: a gas supply module including a carbon dioxide gas cylinder module for supplying carbon dioxide gas; The flow regulation and control module is connected with the outlet of the gas supply module and used for regulating and controlling the output flow of the carbon dioxide gas; The injection mixing module comprises an injection port and a wind tunnel heater, wherein the injection port is connected with the outlet of the flow regulating module, and is positioned at the front end of the wind tunnel heater to ensure that carbon dioxide gas is fully mixed with the main flow as incoming flow; The hypersonic wind tunnel test section, the outlet of the wind tunnel heater sprays mixed gas to the hypersonic wind tunnel test section through a spray pipe; The image feedback module comprises an image acquisition unit and an image processing unit, wherein the image acquisition unit is used for acquiring Rayleigh scattering images in a hypersonic wind tunnel test section, the image processing unit is used for analyzing quality indexes of the Rayleigh scattering images, and the image acquisition unit is connected with the i