基于波长调制光谱(WMS)理论,提出一种利用光谱拟合实现燃烧场气体参数测量的方法;通过拟合谱线的谐波信号实现谱线积分吸光度、多普勒线宽和碰撞线宽的测量,进而实现燃烧场内气体温度、压强和水蒸气浓度的测量;通过数值仿真研究了积分吸光度和碰撞线宽对谐波信号的影响,并在样品池中进行实验研究。结果表明:谐波信号光谱对积分吸光度的灵敏度约为1,而对碰撞线宽的灵敏度则随碰撞线宽增大而先增大后基本不变;光谱拟合测量方法具有较高的测量精度,气体温度、压强、水蒸气物质的量分数的测量值与预测值的最大相对偏差分别小于4%、6%、5.5%。

Based on wavelength modulation spectroscopy (WMS) theory, a measurement method for gas parameters in combustion flow is put forward using spectroscopy fitting. Taking advantage of fitting harmonic signals of spectral lines, the integral absorbance, Doppler width, and collisional width are measured, and then the gas temperature, pressure, and vapour concentration are measured. The numerical simulation is used to investigate the effect of the integral absorbance and collisional width on harmonic signals, and experiments are conducted in a sample cell. The results show that the sensitivity of the harmonic signal spectrum to integral absorbance is nearly 1. However, the sensitivity of the harmonic signal spectrum to collisional width firstly increases and then keeps invariant approximately with the increase of collisional width. The fitting method has a high measurement accuracy. Compared with predicted values, the maximum measurement errors of measured temperature, pressure, and vapour mole fraction are less than 4%, 6%, and 5.5%, respectively.