边界层抽吸和脉动反压作用下隔离段内流动特性研究

A Study of Flow Characteristics in Isolator with Effects ofBoundary Layer Suction and Oscillating Back Pressure

关键词:  边界层抽吸  脉动反压  激波串  迟滞现象  隔离段

Key words:  Boundary layer suction  Oscillating back pressure  Shock train  Hysteresis phenomenon  Isolator

摘要:

为了解上游边界层抽吸控制和下游周期脉动反压作用下隔离段内流动特性，采用非定常数值模拟和理论分析相结合的方法，对来流Ma=2情况下的隔离段内激波串动态演化特性、激波串形态结构变化以及激波串演化迟滞现象进行了研究。结果表明，在脉动反压和边界层抽吸作用下，激波串在上游抽吸狭缝与下游隔离段出口之间周期振荡，振荡频率与脉动反压一致。在振荡过程中，首道激波串形态在规则反射与马赫反射以及马赫反射与弧形激波（包含正激波）之间相互转换。边界层抽吸将激波串固定在抽吸狭缝位置，有效提高了隔离段抗反压性能，脉动频率越大，可承受的瞬态反压峰值越大。在一个振荡周期内，激波串向上移动速度较向下移动更快，且在上下移动过程中形态变化存在迟滞现象。

Abstract:

To investigate the flow characteristics in the isolator influenced by the boundary layer suction at upstream and the oscillating back pressure at downstream, unsteady numerical simulation and theoretical analysis methods are used to study the shock train dynamic evolution, the structure variation and the hysteresis as the upstream flow condition is Ma=2. Results show that the boundary layer suction and oscillating back pressure can induce the shock train oscillating periodically between the suction position and the isolator outlet, and the oscillation frequency is identical to the back pressure frequency. During an oscillation process, the first shock train varies between a regular reflection and a Mach reflection or between a Mach reflection and an arc shock (including a normal shock). Besides, the boundary layer suction impels the shock train fixed at the suction slot, which effectively improves the resistance capability of the isolator to the back pressure, and the peak value of the back pressure increases as the oscillation frequency increases. Results as well exhibit that during an oscillation period, the shock train moves upwards faster than downwards, and a hysteresis for the shock structure occurs as the shock train moves up and down.