脉冲控制模式电弧等离子体对凹腔性能改变的研究

Research on the Performance Change of Cavity by Pulsed Control Plasma

基于准直流电弧放电热阻塞原理,以超燃燃烧室凹腔为研究对象,在凹腔后向台阶上部与凹腔底部靠近前壁面附近布置电极,脉冲控制方式产生丝状等离子体,分析了不同脉冲控制频率下壁面压力、剪切层、凹腔阻力以及质量交换率等性能参数的变化。结果表明:前后缘附近特征点的第一振荡特征频率都接近脉冲控制频率,之后的特征频率则与控制频率成倍频关系;丝状等离子体的存在破坏了凹腔内大回流区结构;等离子体对凹腔产生了预热效果;等离子体的存在减小了凹腔冷流阻力,且在较高控制频率下的阻力系数更低;凹腔质量交换率因等离子体的存在而大幅提高,较高控制频率下具有更高的质量交换率。

The effect of quasi-DC discharge plasma filament on the cavity in a scramjet combustor is numerically investigated based on the dominant thermal mechanism. The electrodes are located near the upper edge of the back- step and at the bottom of the cavity. And plasma filament is formed in pulsed control mode. Change of prformace parameters such as wall pressure, shear layer, cavity drag force and mass ex-change rate under the different pulsed control frequencies is analyzed. Simulation results demonstrate that the first oscillation frequencies of the key points are close to the pulsed control frequencies, and other oscillation frequencies are the multiple of the pulsed control frequencies. The big recirculation zone is destroyed by the plasma filament, yet the cavity is preheated. The drag coefficient drops more apparently with higher control frequency, while the rate of mass exchange increases much more by the plasma, the mass exchange rate is higher under higher control freGuencv.