交流介质阻挡放电等离子体主动控制S形进气道流动分离的实验研究

Experimental Research on Active Control of S-Shaped Inlets Flow Separation by AC-DBD Plasma

关键词:  S形进气道  流动控制  DBD等离子体  流动分离  总压畸变

Key words:  S-shaped inlet  Flow control  DBD plasma  Flow separation  Total pressure distortion

摘要:

S形进气道内的流动分离和二次流造成进气道出口压力损失和气流畸变较为严重，严重影响发动机的工作性能。为改善其流场特性，采用交流介质阻挡放电（Alternating current dielectric barrier discharge，AC-DBD）等离子体激励器主动控制进气道内的流场。在来流风速为10m/s，雷诺数Re_D为1.35×10⁵的工况下，探究了控制位置、布局形式对控制效果的作用规律，从流向和出口截面流场及压力分布出发，探究了主动控制的机理。结果表明，AC-DBD等离子体激励器能够提高壁面静压恢复系数，抑制流动分离并改善出口压力畸变。激励器控制位置在分离点附近最佳，且以诱导气流与来流平行的布局形式最优。在本实验范围内，出口静压系数提高了8.94%，出口稳态畸变指数降低了4.58%。其控制机理是DBD等离子体产生的诱导气流直接加速边界层运动，提高边界层抵抗逆压梯度的能力，从而抑制流动分离。同时，抑制二次流运动，降低压力畸变。

Abstract:

The flow separation and secondary flow in the S-shaped inlets cause serious pressure loss and airflow distortion at the outlet of the inlet， which seriously affects the working performance of the engine. In order to improve its flow field characteristics， the alternating current dielectric barrier discharge（AC-DBD）plasma actuator is used to actively control the flow field in the inlet. Under the working conditions of the incoming wind speed of 10m/s and the Reynolds number Re_D of 1.35×10⁵， the effects of the control position and layout form on the control effect were explored. The mechanism of active control was explored from the flow direction， outlet section flow field and pressure distribution. The results show that the AC-DBD plasma actuator can improve the wall static pressure recovery coefficient， suppress the flow separation and improve the outlet pressure distortion. The actuator control position is optimal near the separation point， and is optimal in a layout that induces the airflow to be parallel to the incoming flow. Within the scope of this experiment， the outlet static pressure coefficient increased by 8.94%， and the outlet steady-state distortion index decreased by 4.58%. The control mechanism is that the induced airflow generated by the DBD plasma directly accelerates the movement of the boundary layer and improves the ability of the boundary layer to resist the adverse pressure gradient， thereby inhibiting flow separation. At the same time， the movement of the secondary flow is suppressed and the pressure distortion is reduced.