AN INVESTIGATION ON A SUPERSONIC FLOW CO CHEMICAL LASER

利用激波风洞装置测量了超声速流动CO化学激光器的小信号增益系数。还对激光腔内各种反应的化学发光进行了直观观察，结果表明，混合层在下游方向的发展是非常渐进的，这与采用薄剪切层近似的数值计算所证明的一样。数值计算表明，在混合层仍占总流动宽度的一小部分的位置处，小信号增益系数开始减小。因此，为了获得更高的平均增益，比本实验的喷嘴小得多的喷嘴是可取的。预测的增益沿着流动的分布与实验结果相当吻合。结果表明，边界层的存在和壁催化的大小在决定激光器性能方面起着决定性的作用。

Small signal gain coefficients of a supersonic flow CO chemical laser were measured using a shock tunnel facility. The visual observation of the chemical luminescence from various reactions in the laser cavity were also performed and it was shown that the development of the mixing layer in the downstream direction is very gradual as was demonstrated by the numerical calculation using the thin shear layer approximation. The numerical calculation showed that the small signal gain coefficients begin to decrease at a location where the mixing layer is still a small portion of the total flow width. Therefore, much smaller nozzles than those of the present experiment are desirable in order to attain a higher average gain. The predicted distribution of the gains along the flow agreed fairly well with the experimental results. It was clearly demonstrated that the presence of the boundary layers and the magnitude of the wall catalysis play decisive roles in determining the laser performance.