端壁吸/吹气对超声速压气机叶栅流场影响机理的对比研究

Comparison Between Effects of Endwall Suction and Air Injection on Flow Field of a Supersonic Compressor Cascade

关键词:  激波/附面层干扰  超声速压气机叶栅  角区分离  附面层抽吸  附面层吹气

Key words:  Shock wave/boundary layer interaction  Supersonic compressor cascade  Corner separation  Boundary layer suction  Boundary layer injection

摘要:

附面层吸/吹气是抑制流动分离、提高压气机叶片负荷的有效技术途径。针对超声速压气机叶栅内激波诱导的角区分离，分别采用多种不同的端壁吸/吹气方案对其进行流动控制，旨在探索端壁吸/吹气对激波干涉下角区分离的控制机理，并对比分析端壁吸/吹气对超声速压气机叶栅角区分离的控制效果。结果表明：在激波/端壁附面层干涉下，该超声速压气机叶栅内存在大范围的激波诱导角区分离，角区分离使得该超声速叶栅存在强三维效应，二维叶栅中的单正激波变为“斜激波+正激波”结构，叶中吸力面尾缘开式分离变为闭式分离；端壁吸气可有效抑制该超声速叶栅的角区分离，吸气后近端壁区损失系数大幅降低，最优端壁吸气缝方案的起始点与亚声速压气机叶栅相同，但端壁吸气后叶中的双激波结构变为单正激波结构，叶中流动分离增大；端壁吹气也可有效抑制角区分离，其控制效果略优于端壁吸气，其原因是吹气缝处的静压高于吸气缝，对激波的增强作用弱于端壁吸气；与端壁吸气方案不同的是，最优端壁吹气缝方案的起始点位于叶片前缘。

Abstract:

Boundary layer suction and air injection are among the proved methods of controlling flow separation and improving blade loading of compressors. In this study, different endwall suction/air injection schemes were designed and investigated in a supersonic compressor cascade, in order to reveal the control mechanism of shock wave induced corner separation and the difference between endwall suction and air injection. Results show that significant area of corner separation appeares in the supersonic compressor cascade passage under shock wave/boundary layer interaction. Because of the influence of severe corner separation, the single-normal passage shock wave in the two-dimensional cascade changes to a double-shock wave (an oblique shock wave and a normal shock wave) in the mid-span of the three-dimensional supersonic compressor cascade, and the open separation changes to a closed separation on the suction surface near the trailing edge. Endwall suction can effectively control the corner separation, the loss coefficient near the endwall is reduced significantly. The optimal endwall suction scheme is the same with subsonic compressor cascade in the open literatures. After endwall suction, the double-shock wave in the mid-span changes to a single-normal shock wave, and the separation near the trailing edge of the mid-span is enlarged. Endwall air injection can also effectively reduce corner separation of the supersonic compressor cascade, and the control effects is superior to endwall suction, which is because the static pressure at the air injection slot are higher than that at the suction slot. The optimal endwall air injection scheme is located at the leading edge of the cascade.