Development of high-resolution n(2) coherent anti-stokes Raman scattering for measuring pressure, temperature, and density in high-speed gas flows.
Development of high-resolution n(2) coherent anti-stokes Raman scattering for measuring pressure, temperature, and density in high-speed gas flows.
复制标题
开发高分辨率 n(2) 相干反斯托克斯拉曼散射，用于测量高速气流中的压力、温度和密度。
作者：
M. A. Woodmansee;R. Lucht;J. Dutton
利用高分辨率N(2)相干反斯托克斯拉曼散射（CARS）技术，在光学可及的气室和欠膨胀声波射流流场中获得了压力、温度和密度的平均和瞬时测量值。这种非侵入式方法解决了nu = 0 ？1 N(2) q分支到Domega内= 0.10 cm（-1）。为了从实验光谱中提取热力学信息，利用N(2)光谱建模程序生成理论光谱，用最小二乘方法拟合实验光谱。在气电池中，cars测量的压力与传感器测量的压力比较有利。在亚大气条件下，单发CARS压力测量的精度和准确度增加。沿着欠膨胀射流的中心线，平均CARS P/T/rho测量值与从reynolds -average Navier-Stokes计算流体动力学模拟中提取的类似量之间的一致性通常很好。这种CARS技术能够捕捉到进入马赫盘的M = 3.4气流的低压和低温条件，以及这种正常激波下游的亚音速条件。
Mean and instantaneous measurements of pressure, temperature, and density have been acquired in an optically accessible gas cell and in the flow field of an underexpanded sonic jet by use of the high-resolution N(2) coherent anti-Stokes Raman scattering (CARS) technique. This nonintrusive method resolves the pressure- and temperature-sensitive rotational transitions of the nu = 0 ? 1 N(2) Q-branch to within Domega = 0.10 cm(-1). To extract thermodynamic information from the experimental spectra, theoretical spectra, generated by a N(2) spectral modeling program, are fit to the experimental spectra in a least-squares manner. In the gas cell, the CARS-measured pressures compare favorably with transducer-measured pressures. The precision and accuracy of the single-shot CARS pressure measurements increase at subatmospheric conditions. Along the centerline of the underexpanded jet, the agreement between the mean CARS P/T/rho measurements and similar quantities extracted from a Reynolds-averaged Navier-Stokes computational fluid dynamic simulation is generally excellent. This CARS technique is able to capture the low-pressure and low-temperature conditions of the M = 3.4 flow entering the Mach disk, as well as the subsonic conditions immediately downstream of this normal shock.