超声速气流中分子弛豫过程的主/被动控制方法研究

High accurate numerical simulation, high speed laser schlieren apparatus, Nano-particle Planar Laser Scattering(NPLS), and small signal gain measurement technology are synthetically used for studying the initiative/passive flow control methods of the molecule relaxation processes in the supersonic gas flow.A LES numerical simulation method coupling with more accurate relaxation models is established; The control mechanism of pure nozzle profile restriction effect on the molecule relaxation processes is studied,so that a new nozzle profile design method which integrate the gasdynamic demands and relaxation demands is developed for satisfying the requirements of relaxation processes control. The sensitivity of the initiative flow control method using 'periodic temperature perturbation' effect on the molecule relaxation processes in the supersonic mixing layer of different layer thickness,convection mach number,total temperature and total pressure is studied. After that a new and high performance initiative flow control method for molecule relaxation processes control is developed. The research of this project will provide important reference and innovatory method for high performance and more efficient gasdynamic laser nozzle.

综合运用高精度数值仿真、高速激光纹影、纳米粒子平面激光散射测量（NPLS）、小信号增益测量等手段，对超声速气流中分子弛豫过程的主/被动控制方法进行研究：建立耦合更加精确弛豫模型的大涡模拟数值仿真手段；研究纯气动型面约束的被动控制方法对分子弛豫过程的控制机理，从对弛豫过程控制的需求出发发展综合考虑"气动+弛豫"需求的新型喷管型面设计方法；研究不同射流厚度、对流马赫数、总温、总压的超声速射流混合层中分子弛豫过程对"周期性温度激励"控制手段的感受性，进而发展新型高效的超声速气流弛豫过程主动控制方法。本项目研究将为发展高性能和高效率气动二氧化碳激光器喷管提供重要参考和创新发展思路。

采用理论分析、实验研究和数值仿真的方法，对超声速气流中弛豫过程的主/被动控制方法进行研究。首先基于OpenFoam建立起一套更加精确的预混/混合型气动二氧化碳激光器喷管二维/三维增益场数值仿真手段。被动控制方法方面：首次将一种可以局部调节喷管型面的新型喷管设计思想——任意长度喷管（ALN）设计思想运用于气动二氧化碳激光器喷管设计，建立同时满足气动和弛豫要求的型面设计方法。研究了筛形喷管和基于“主喷管喉部喷射副气流”喷管构型的弛豫过程控制效果。主动控制方法方面：首次将基于周期性温度激励的主动控制技术引入混合型气动CO2激光器研究，研究了采用周期性温度激励时混合型气动CO2激光器的混合特性、流场特性及小信号增益分布特性。为了完成实验设计了燃烧驱动混合型气动CO2激光器的高温氮气发生器方案，成功点火，且燃烧稳定性较好。