Research of Combustion Control in Dual-Mode Ramjet Combustor with Staged Fuel Injection

对双模冲压发动机燃烧室的实际构型--矩形扩张段通道内的超音速加热燃烧流动进行了实验和数值研究。介绍了一种激光速度和浓度测量方法，用于大分离区域流场的非侵入式诊断。在实验研究中，将一个或两个H2/N2等离子体炬连接到风道上，通过放电和燃烧火焰中的氢向超音速气流供热，观察到准激波的形成和燃烧模式的转变。结果表明，风道发散对拟激波的形成和燃烧模式的转变有较大的抑制作用。不同发散角的实验结果表明，在发散通道中产生假激波所需的附加热可以用准一…来估算。更多维度的理论。当等面积管道中的等离子体炬产生拟冲击波时，与直管相连的发散管道中的另一个等离子体炬需要增加一定的热量才能影响上游段。计算结果表明，在直管和扩径管道中进行分级喷油比单次喷注相同总量的燃料可以获得更大的推力。在数值研究中，得到了矩形通道拐角处厚边界层分离导致的拟激波波阵面的上游传播，以及扩径管道内明显的不对称分离等详细的流场特征。数值结果验证了为补偿管道分流的影响所需的加热量的准一维理论评估。利用粒子图像测速仪，我们得到了有激波和涡流的550米/S流动中的平均三维速度分布。利用丙酮平面激光诱导荧光法，获得了喷射剂在整个流场中的定性分布以及喷射口附近的马赫数分布。这些测量技术适用于有假激波和燃油喷射的流动。较少

Supersonic flow with heat addition and combustion in rectangular ducts with diverging section, which are realistic configuration for the combustor of dual-mode ramjet engines, was investigated experimentally and numerically. Laser measurement methods of velocity and concentration were introduced for non-intrusive diagnostics of the flowfields with large separated regions.In the experimental study, one or two H2/N2 plasma torches were attached to the duct for heat addition to the supersonic airstream by electrical discharge and combustion of hydrogen in the feedstock of the torch, and formation of pseudo-shock wave and transition of combustion mode were observed. It was found that the divergence of the duct considerably suppress the formation of pseudo-shock waves and the transition of combustion mode. Results of experiments with various diverging angles indicated that the additional heat required to produce the pseudo-shock wave in the diverging duct could be estimated by the quasi-one … More dimensional theory. When the pseudo-shock wave was produced by the plasma torch in the constant area duct, another plasma torch in the diverging duct connected to the straight duct required certain amount of heat addition to affect the upstream section. From this result, it was shown that the staged fuel injection in the straight and diverging ducts could deliver more thrust than the single injection of the same total amount of fuel.In the numerical study, detailed features of the flowfield, such as the upstream propagation of the pseudo-shock wave front led by separation of thick boundary layer at the corner of the rectangular duct, and significant asymmetric separation in the diverging duct, were obtained. Numerical results validated the quasi-one dimensional theoretical evaluation of the heat addition required to compensate the influence of duct diverging.Using the particle image velocimetry, we obtained averaged three-dimensional velocity distributions in the flow up to 550m/s with shock waves and vortices. By the acetone planar laser induced fluorescence method, qualitative distribution of injectant in the whole flow field as well as the Mach number distribution near the injection port were obtained. These measurement techniques are applicable to the flow with the pseudo-shock wave and fuel injection. Less