Development of a Simultaneous Measurement Method of Velocity, Temperature, and Concentration using a Diode Laser in a Supersonic Combustion Flow

本研究旨在开发一种利用紧凑型半导体激光器测量超音速燃烧流中速度、温度和浓度的新方法。该方法基于H2O分子的红外吸收特性，选用InGaSaP半导体激光器探测H2O振动-转动跃迁的1.393μm波段。对H2O分子过渡线的研究表明，两对过渡线分别适用于1300K-2000K和300K-1300K的温度测量。通过与美国科学家的合作，研制了半导体激光控制器、激光校正器光学元件和测量代码，并进行了光纤和半导体激光光学元件的组装；利用东北大学流体科学研究所的超音速燃烧试验装置，对超音速气流和火焰保持柱后的燃烧流动进行了测量试验，以确定…进一步说明了本研究开发的系统的性能。为了将激光探头安装到风洞的测量部分，采用了AR涂层光学窗口、针孔结构和氮气吹扫系统，以最大限度地减少表面反射、火焰辐射和周围空气对激光的吸收的影响。测量结果表明，在超音速气流中，在没有任何数据补偿的情况下，温度和速度的数据与数值估计值吻合得很好。当风洞空气再热器中残留的H2O产生的背景H2O浓度降低时，H2O浓度与估计值相吻合。将燃烧区域的速度数据与激光测速仪测得的平均速度进行了比较，两者吻合较好。尾流区H_2O浓度与基于H_2-空气火焰化学平衡的估算值也符合得很好。从这些结果中，证实了本研究开发的诊断方法的准确性和可行性。较少

This research was aimed to develop a new measurement method of velocity, temperature, and concentration in supersonic combustion flow by using a compact diode laser. This method is based on the infrared absorption characteristics of H_2O molecules.A InGaSaP diode laser was selected to detect 1.393 μm band of H_2O vibration-rotation transition. The investigation of the transition lines of H_2O molecules proved that two pairs of transition line are suitable for the temperature measurement in the range of 1300 K - 2000 K and 300 K - 1300 K separately. By collaboration research with a scientist in USA, the diode laser controller, laser corrector optics, and the measurement code were developed, and the assembling of the optical fibers and diode-laser laser optics were conducted.By using a supersonic-combustion test facility of Institute of Fluid Science, Tohoku University, measurement tests of supersonic air-flow and the combustion flow behind a flame holding strut were conducted to confirm … More the performance of the system developed in this research. For installing the laser probes to the measurement section of the wind tunnel, AR coated optical windows, pin-hole structure, and nitrogen-purge system were employed in order to minimize the effects of the surface reflection, flame radiation, and laser absorption by surrounding air. Results of the measurements showed that, in supersonic air-flow, data of temperature and velocity agreed well with the numerically estimated values without any data compensation. H_2O concentration agreed with estimated value when the background H_2O concentration caused by the residual H_2O via the air reheater of the wind tunnel was reduced. The velocity data for the combustion region was compared with the mean velocity measured by LDV and they agreed well. H_2O concentration was also agreed well with the values estimated based on chemical equilibrium of H_2-air flames in the wake region. From these results, the accuracy and feasibility of the diagnostic method developed in this research were confirmed. Less