CN-121877838-B - Quantitative analysis method for influence of gas type and concentration on FLEET signals

Abstract

A quantitative analysis method of influence of gas types and concentration on FLEET signals belongs to the technical field of aerodynamic test. In order to solve the problem that the FLEET technology is applied to quantitative identification of gas components and concentrations, the invention performs test system construction, determines the influence of gas pressure on FLEET signal strength under a single gas test condition, determines the influence of gas pressure of different kinds of gases on FLEET signal strength under different kinds of single gas test conditions, determines the influence of gas pressure of combined gases on FLEET signal strength under combined gas test conditions, determines the influence of gas pressure on FLEET signal life under the single gas test conditions, and determines the influence of gas pressure of combined gases on FLEET signal life under combined gas test conditions. The invention realizes quantitative characterization of the influence of the gas species and the concentration thereof on FLEET signals.

Inventors

• ZHONG HONGJIE
• GUO TONGYU
• CHANG GUANG
• Men Guannan

Assignees

• 中国航空工业集团公司沈阳空气动力研究所

Dates

Publication Date

20260512

Application Date

20260320

Claims (7)

1. 1. A method for quantitatively analyzing the influence of a gas species and its concentration on FLEET signals, comprising the steps of: S1, building a test system; S2, determining the influence of gas pressure on FLEET signal intensity under a single gas test condition; S3, under the single gas test conditions of different types, analyzing the influence of the gas pressure of the different types of gases on FLEET signal intensity; s4, under the test condition of the combined gas, analyzing the influence of the gas pressure of the combined gas on FLEET signal intensity; s5, under the single gas test condition, analyzing the service life influence of the gas pressure on FLEET signals; S6, determining the influence of the gas pressure of the combined gas on FLEET signal life under the combined gas test condition.
2. 2. The quantitative analysis method for influence of gas types and concentrations on FLEET signals according to claim 1 is characterized in that the connection relation of a test system in the step S1 is that a high-pressure gas source I (1), a pressure reducing valve I (3) and a vacuum chamber (7) are sequentially connected, a high-pressure gas source II (2), a pressure reducing valve II (4) and the vacuum chamber (7) are sequentially connected, the vacuum chamber (7) is further respectively connected with a precision digital display pressure gauge (5) and a vacuum pump (15), laser emitted by a femto-second laser (12) is reflected to a reflecting mirror I (10) through a reflecting mirror II (11) and then projected to a plano-concave lens (9) and a plano-convex lens (8) and then irradiated into the vacuum chamber (7), an imaging system (6) is used for shooting FLEET signal images in the vacuum chamber (7), and a computer device (13) is connected with the imaging system (6) and is used for storing FLEET signal images shot by the imaging system (6) and processing images to obtain intensity information of FLEET signals.
3. 3. The quantitative analysis method for influence of gas species and concentration thereof on FLEET signal according to claim 2, wherein the imaging system (6), vacuum chamber (7), plano-convex lens (8), plano-concave lens (9), reflecting mirror I (10), reflecting mirror II (11) in step S1 are placed on a lifting table (14) respectively, the optical path is adjusted by the lifting table (14), Ensure FLEET that the signal image is generated and acquired at the central position of the vacuum chamber (7).
4. 4. A method for quantitatively analyzing the influence of a gas species and its concentration on FLEET signals as claimed in claim 3, wherein the imaging system in step S1 is composed of a high-speed camera, an image intensifier and a tele lens.
5. 5. The method for quantitative analysis of influence of a gas species and concentration thereof on FLEET signals according to claim 4, wherein the specific implementation method of step S2 includes the steps of: s2.1. Closing the pressure reducing valve I (3), pumping the vacuum chamber (7) to a vacuum environment by using a vacuum pump (15), and recording the initial pressure by using a pressure gauge (5) Acquiring FLEET signal images corresponding to the initial pressure using an imaging system (6) The pressure sequence is obtained by adjusting the pressure reducing valve I (3) to stepwise increase the gas pressure, recording the pressure and collecting FLEET signal images at the same time And FLEET signal image sequences M is the total number of pressure conditions, For the mth pressure to be the mth pressure, FLEET signal images corresponding to the mth pressure; S2.2 for Eliminating random noise in an image by using Gaussian filtering in a small range, performing binarization processing, extracting an edge point set of FLEET signals by a Canny edge detection method, and obtaining a left boundary of FLEET signals by taking minimum and maximum values in the horizontal direction in the edge point set And right boundary Taking the maximum and minimum in the vertical direction yields the upper boundary of FLEET signals And lower boundary A rectangular frame is determined as a mask based on the four boundaries: ; Wherein, the Representing a pixel coordinate in the image; And then obtaining a larger rectangular frame boundary by expanding the rectangular frame at the boundary of the added area, thereby obtaining: ; ; ; ; wherein k is a proportionality coefficient, To expand the left boundary of the FLEET signal, To enlarge the right boundary of the FLEET signal, To enlarge the lower boundary of the FLEET signal, An upper boundary for the expanded FLEET signal; The enlarged mask The method comprises the following steps: ; S2.3. FLEET Signal image for ith pressure Calculating the background mean value, and carrying out mean value calculation on all pixels of the background area, namely All pixels of 0 calculate the mean Then to Calculating a background mean value to obtain a background mean value sequence ; S2.4. FLEET Signal images corresponding to the ith pressure Calculate FLEET the intensity of the signal, i.e. for 1, And calculating the average value of the gray values of all pixels with the gray value of the first 20 percent Then to Calculating FLEET signal intensity to obtain FLEET signal intensity sequence ; S2.5. All And Corresponding subtraction to obtain FLEET signal strength sequence without background interference Wherein The intensity of the signal at the mth FLEET; s2.6 determination of the maximum in the intensity sequence of the signal of analysis FLEET Obtaining the corresponding pressure Is determined to be under the gas at the pressure of The strongest FLEET signal is obtained.
6. 6. The method for quantitatively analyzing the influence of a gas species and its concentration on FLEET signals according to claim 5, wherein the specific implementation method of step S3 includes the steps of: S3.1, according to the method of the step S2, respectively carrying out experiments under different gas types including nitrogen, oxygen and air, under each gas type, changing the gas pressure in the vacuum chamber and collecting corresponding FLEET signal images, calculating FLEET signal intensity corresponding to different pressure under each gas type, and determining the maximum FLEET signal intensity and corresponding pressure under each gas type ; S3.2. Recording the maximum FLEET signal intensity for each gas species And the corresponding pressure under the gas condition Then the Is the optimal gas condition for achieving the maximum FLEET signal intensity.
7. 7. The method for quantitative analysis of influence of a gas species and concentration thereof on FLEET signals according to claim 6, wherein the specific implementation method of step S4 includes the steps of: S4.1 based on the optimal gas conditions obtained in step S3, adjusting the pressure reducing valve I (3) to adjust the pressure to the value determined in step S3 Then regulating the pressure reducing valve II (4) under different gas conditions, increasing the pressure stepwise, recording the pressure, and collecting FLEET signal images to obtain a pressure sequence of the combined gas Image sequence corresponding to pressure sequence of combined gas ; S4.2. Then image series corresponding to the pressure series based on the combined gases Calculating FLEET signal intensity of the combined gas according to the method of the step S2 to obtain Wherein The mth FLEET signal intensity for the combined gas; s4.3. By analysis Maximum value of (2) Obtaining the corresponding pressure Determining that the total gas pressure is under the current combined gas condition And the high-pressure air source I (1) provides air with the pressure of When the strongest Fleet signal is obtained; S4.4. Judgment And obtained in step S2 If (3) > The current combined gas conditions proved to obtain a stronger FLEET signal than the single gas conditions, otherwise not.

Description

Quantitative analysis method for influence of gas type and concentration on FLEET signals Technical Field The invention belongs to the technical field of aerodynamic test, and particularly relates to a quantitative analysis method for influence of gas types and concentrations thereof on FLEET signals. Background With the continuous and deep research of high enthalpy flow, plasma flow and complex gas reaction processes, non-contact gas tracing and diagnosis technology based on laser-induced fluorescence is widely focused in the fields of aerodynamic test, combustion diagnosis, high-temperature gas physical property measurement and the like. The femtosecond laser electronic excitation molecular marking technology (Femtosecond Laser Electronic Excitation Tagging, FLEET) is used as a novel molecular marking tracing means, and the femtosecond laser is utilized to directly excite molecules in gas to form fluorescent marks, so that the method has the advantages of no need of externally adding trace particles, high time resolution, small disturbance of a convection field and the like, and has good applicability in high-speed, high-temperature and unsteady gas environments. In the prior art, FLEET technology is mainly used for flow field speed measurement and flow structure visualization, and the generation of fluorescence signals is closely related to parameters such as gas molecular species, gas concentration, environmental pressure and the like. However, in practical application, FLEET signal intensities and service lives under different gases and combination conditions are obviously different, and the detectability, measurement accuracy and feasibility of an experimental scheme of the signals are directly affected. Particularly, under the condition of low pressure or complex gas components, FLEET fluorescent signals are weak and are easy to be interfered by background light, scattered light and random noise, so that difficulty is brought to quantitative discrimination of the gas components and the concentration. The existing analytical methods for FLEET signals focus on qualitative comparisons or empirical determinations, lacking a systematic, reproducible experimental procedure for quantitative assessment of the effect of different gas species and combinations thereof on FLEET signal intensity and lifetime under controlled pressure conditions. Meanwhile, the traditional image processing method is insufficient in stability in the aspects of signal region extraction, background suppression and signal intensity quantification, and a unified evaluation standard is difficult to form among different experimental conditions, so that the further application of FLEET technology in quantitative identification of gas components and concentrations is limited. Therefore, a gas component characterization method based on FLEET signal intensity and life analysis is needed, and system characterization of FLEET signal intensity and life under different gases and combination conditions is realized by constructing a controlled gas environment and combining stable image processing and signal quantification strategies, so that reliable basis is provided for distinguishing gas components and concentrations. Disclosure of Invention The invention aims to solve the problem that FLEET technology is applied to quantitative identification of gas components and concentrations, and provides a quantitative analysis method for influence of gas types and concentrations thereof on FLEET signals. In order to achieve the above purpose, the present invention is realized by the following technical scheme: a quantitative analysis method for influence of gas types and concentrations thereof on FLEET signals comprises the following steps: S1, building a test system; S2, determining the influence of gas pressure on FLEET signal intensity under a single gas test condition; S3, under the single gas test conditions of different types, analyzing the influence of the gas pressure of the different types of gases on FLEET signal intensity; s4, under the test condition of the combined gas, analyzing the influence of the gas pressure of the combined gas on FLEET signal intensity; s5, under the single gas test condition, analyzing the service life influence of the gas pressure on FLEET signals; S6, determining the influence of the gas pressure of the combined gas on FLEET signal life under the combined gas test condition. Furthermore, the connection relation of the test system in the step S1 is that a high-pressure air source I, a pressure reducing valve I and a vacuum chamber are sequentially connected, the high-pressure air source II, the pressure reducing valve II and the vacuum chamber are sequentially connected, the vacuum chamber is also respectively connected with a precision digital display pressure gauge and a vacuum pump, laser emitted by a femtosecond laser is reflected to the reflecting mirror I through the reflecting mirror II and then projected thro