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针对可调谐半导体激光器吸收光谱(TDLAS)基于多普勒效应测速方法在燃气流速测量中频移量小、误差较大的问题,提出了结合固定波长吸收光谱法与互相关法的燃气速度测量方法。考虑碳氢燃料燃烧产物特点,选取H2O分子7 185.597cm~(-1)吸收谱线,通过布置上下游两束固定波长吸收光谱测点,分析两信号的互相关特性来计算得到燃气速度。利用平面火焰炉实验系统对该方法测量燃气速度开展实验研究,获得了变工况下燃气速度随时间的变化情况。在相同工况下开展数值计算,将测量结果与数值模拟计算结果进行对比,相对偏差不超过8%。同时将该方法初步应用于煤油燃料火箭基组合循环发动机(RBCC)的高速羽流速度测量,获得了上下游探测器脉动信号,通过互相关分析计算得到了羽流速度,验证了该方法的可行性。实验结果表明,该燃气速度测量方法具有测量范围宽、测量精度高,环境干扰小等优点。提出的方法为发动机燃气速度测量提供一种简单可靠的测量方法。
Aiming at the problem that tunable semiconductor laser absorption spectrum (TDLAS) based on Doppler effect velocimetry method has small frequency shift and large error in gas flow velocity measurement, a gas velocity measurement method based on fixed wavelength absorption spectroscopy and cross-correlation method is proposed. Considering the characteristics of the combustion products of hydrocarbon fuel, the absorption line of H2O of 7 185.597cm ~ (-1) was selected, and the gas velocity was calculated by arranging two fixed wavelength absorption spectrum measuring points on the upstream and downstream and analyzing the cross correlation of the two signals. The flat gas furnace experimental system is used to measure the gas velocity in this method. Experimental results show that the gas velocity changes with time under varying conditions. Under the same conditions, the numerical calculation is carried out, the measured results are compared with the numerical simulation results, the relative deviation does not exceed 8%. At the same time, the method is applied to the high-speed plume velocity measurement of kerosene-fuel rocket-based combined cycle engine (RBCC). The pulse signals of the upstream and downstream detectors are obtained. The plume velocity is obtained through the cross correlation analysis and the feasibility of the method is verified Sex. Experimental results show that the gas velocity measurement method has the advantages of wide measurement range, high measurement accuracy and small environmental interference. The proposed method provides a simple and reliable method of measurement of engine gas velocity.