燃烧流场线CARS测温技术研究

摘要

常规CARS采用凸透镜聚焦多束激光于空间一点,在满足相位匹配条件下产生携带该点温度信息的CARS信号。常规CARS一次只能测量一个空间点的温度,难以满足燃烧流场深入研究需要。为了提高CARS测量能力,使得CARS在一次测量中获得更多信息,提出了线CARS测量方法。线CARS测量方法在常规CARS基础上采用柱面凸透镜替换普通凸透镜,使得聚焦位置由焦点变为焦线。由于焦线上的点大部分满足相位匹配关系,因此可以同时获得多点CARS信号。后续光路同样采用柱面凸透镜替换普通凸透镜,通过光谱仪和 ICCD相机将 CARS信号传输至计算机,解析出聚焦线上 CARS信号对应的温度信息,实现CARS测量能力由“点”到“线”的提升。基于平面火焰炉的燃烧实验结果表明：线 CARS 可以一次有效测量200个空间点的温度信息,空间测量长度约3.6 mm,空间分辨率约18μm,测量结果相对不确定度优于7%,在保持测量精度的同时有效丰富了单次测量信息。%Some laser beams meet at a single point by a convex len in normal coherent anti-Stokes Raman scattering (CARS), and the CARS signal with temperature information of the focal piont yields under phase matching.Normal CARS can only get the temperature of one spatial piont in one measurement,which can not meet the needs of deep research on combustion flow field.In order to get more information in one test and improve the measuring capacity of CARS,line CARS (L-CARS)was pres-ented.In L-CARS,convex lens are replaced by cylindrical convex lens to get a focal line,and nearly all the points on the line meet the phase matching.So,the CARS signal of each point on the line yield in one test.Cylindrical convex lens are also used in subsequent beam path to focus the CARS signals into spectrometer,and ICCD camera transfers the signals to computer to ac-quire the temperature of each point.Then,the measuring capacity of CARS is advanced from piont measuring to line measuring. Experimental results based on plain flame furnace suggest that L-CARS can acquire about 200 points’temperatures effectively in one test,and the length of the measuring line is about 3.6mm.The spatial resolution is about 18μm and the uncertainty is less than 7%,which is as the same as the ordinary CARS’s.