RESEARCH ON COMBINED CYCLE ENGINES FOR SUPER AND HYPERSONIC AEROSPACE PROPULSION

超音速贯流风扇气动动力学：利用新开发的CFD和双线性化理论程序对叶栅颤振边界进行了参数研究。后一种代码的实用性已得到证实。采用N-S程序进行数值模拟，研究了STFF型叶栅流动的启动和不启动条件。用流动显示的方法对流场进行了研究。化学反应流动：建立了等离子体炬系统。从理论和实验上验证了活性化学物种对超音速气流中氢气燃烧的启动作用。利用Mie散射和OH排放测量技术，对掺有低反应燃气的超音速气流中产生和控制火焰预燃激波的条件进行了实验研究。建立了一种预测湍流扩散燃烧中NOx浓度的新的计算模型。混合：实验研究了波纹板混合器产生的浓度场、速度场和涡量场的三维结构。从理论上研究了涡旋在混合现象中的行为和作用。冲击波：数值研究了叶栅中不稳定激波运动的机理。材料：提出了一种通过改变表面几何形状来减少残余应力的技术，以防止涂层中由于热应力而产生的裂纹，并从理论上验证了该方法的有效性。

Supersonic Through-Flow Fan (STFF) Aerodvnamics : Parametric studies of the cascade flutter boundaries have been conducted by using the newly developed CFD and Double Linearization Theory codes. The usefulness of the latter code has been confirmed. The start and unstart conditions of STFF cascade flows have been investigated by N-S code numerical simulation. The flow field has been studied by means of the flow visualization.Chemically Reacting Flows : A plasma torch system has been constructed. The effect of active chemical species on initiating the hydrogen combustion in supersonic air flows has been theoretically and experimentally verified. the conditions of generating and controlling the precombustion shock for holding flames in a supersonic air flow mixed with a low-reacting fuel gas have been experimentally investigated by using Mie-scattering and OH emission measurement techniques. A new computational model to predict NOx concentrations in turbulent diffusion combustion has been developedMixing : Three-dimensional structures of concentration, velocity and vorticity fields generated by a lobed plate mixer have been experimentally studied. The behavior and role of vortices in mixing phenomena have been theoretically investigated.Shock Wave : The mechanism of unstable shock motion in cascade has been numerically studied.Material : A residual stress reduction technique by modifying the surface geometry has been proposed to prevent cracks from developing in the coated layr due to thermal stress and its usefulness has been theoretically verified.