超燃冲压发动机隔离段内附面层/激波串相互干扰研究

Investigation of boundary layer/shock wave train interference in a scramjet isolator

隔离段内激波串的产生和发展以及激波/附面层相互干扰现象是极为复杂的,有效地进行激波串的组织是研究隔离段的关键所在,而其性能的好坏直接影响着超燃冲压发动机的性能。采用数值模拟的方法对不同来流附面层厚度工况的二维轴对称隔离段内流场流动特性进行了数值计算,分析了附面层/激波相互作用机理和附面层对隔离段激波串及隔离段性能的影响。结构表明:压缩-膨胀-再压缩-再膨胀……的气流流动挤压过程导致激波串的形成,逆压梯度的存在构成了附面层分离;附面层厚度的增加影响着激波串起始位置和结构;随着附面层厚度的增加,出口总压恢复系数和质量平均马赫数降低,且随着反压增大,变化趋势趋于明显。

The occurance and the development of the isolator shock wave train and the interference phenomenon of shock wave/boundary layer are very complicated. The numerical method was used to simulate the characteristics of the two-dimensional-axis-symmetry isolator internal flow fields under different incoming airflow boundary layer thickness, the interference mechanism of shock wave/boundary layer and the influence of the boundary layer on the isolator shock wave train and the performance of the isolator. The computational results show that the periodical expansion and the compression results in the formation of the shock wave train and the existence of the negative pressure gradients have influence upon the boundary layer separation. The location and the structure of the shock wave train are effected by the incoming airflow boundary layer thickness. With the in- crease of the boundary layer thickness, the total pressure recovery coefficient and average Mach number at outlet decrease. This variation is more significant with the backpressure increasing.