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利用可调谐半导体激光器吸收光谱(TDLAS)燃烧诊断技术,开展了吸气式发动机来流热试实验燃气温度、H2O组分浓度和气流速度测量。选用1392 nm和1395 nm分布反馈式(DFB)半导体激光器,构建了交叉光束时分复用(TDM)系统,通过扫描波长方法,交替调制两个激光器以获得燃气双吸收谱线中心(7185.597 cm-1和7168.437 cm-1)附近吸收光谱。根据双线测温原理,通过双线积分吸收率比值推断燃气静温,并由此温度测量值,结合单线积分吸收率计算燃气中H2O组分浓度,此外,根据成70°夹角双激光束吸收中心的多普勒频移量计算气流速度,从而实现了发动机燃气参数的非接触式和实时在线测量。
Using Tunable Semiconductor Laser Absorption Spectroscopy (TDLAS) combustion diagnostic technology, a gas-heated experiment was carried out to study the gas temperature, H 2 O component concentration and gas velocity measurement. The 1392 nm and 1395 nm distributed feedback (DFB) semiconductor lasers were used to build a crossed beam time-division multiplexed (TDM) system. By scanning wavelength, two lasers were alternately modulated to obtain the center of gas double absorption line (7185.597 cm -1 And 7168.437 cm-1) near the absorption spectrum. According to the principle of two-wire temperature measurement, the gas temperature is deduced from the ratio of two-point integral absorption rate. From this temperature measurement, the concentration of H 2 O component in the gas is calculated according to the single-line integral absorption rate. The Doppler shift of the absorption center is used to calculate the gas velocity, thus enabling non-contact and real-time on-line measurement of engine gas parameters.