高负荷压气机叶栅分离结构及其等离子体流动控制

Separation Structure and Plasma Flow Control on Highly Loaded Compressor Cascade

为揭示高负荷压气机叶栅内部流动损失的产生机理和分布规律以及等离子体气动激励的作用机制,利用拓扑分析和数值计算方法,从计算模型的建立与验证、基准流场的分离结构和等离子体流动控制3个方面展开研究;对总压损失系数分布、拓扑结构和表面流谱与空间流线分布以及旋涡结构进行分析,并开展了激励方式的优化分析。结果表明:随着攻角的增大,固壁面拓扑结构增加了3对奇点,吸力面流向激励改变了固壁面拓扑结构。当攻角为2°时,在吸力面拓扑结构中产生了一对奇点,打断了角区分离线,并引入了一条回流再附线。叶栅流道内部有5个主要涡系,尾缘径向对涡促进流体的展向流动,并成为吸力面倒流的主要组成部分;角涡是一个独立的涡系,其强度和尺度不受等离子体气动激励的影响。吸力面流向激励可以改善叶中流场,但对角区流动作用很小;端壁横向激励可以降低角区流动损失,对叶中流场作用有限;吸力面流向与端壁横向组合激励在整个叶高范围内均可以显著抑制流动分离;端壁横向流动对角区流动分离结构的影响大于吸力面附面层的分离。吸力面流向激励的优化明显降低,而端壁横向激励和组合激励的优化保持并增强了等离子体流动的控制效果。

To discover the rule of flow loss generation and distribution as well as mechanism of plasma aerodynamic actuation in highly loaded compressor cascade,research on the establishment and verification of simulation model,flow separation structure of basic flowfield and plasma flow control is conducted with topology analysis and numerical method.The total pressure loss coefficient distribution,topology structure,surface streamline patterns and three-dimensional streamlines distribution as well as vortex structure are analyzed,and analysis of optimized actuation layouts are conducted.Results show that three pairs of additional singular points of surface topology strucutre generate with the increase of angle of attack.Plasma actuation changes solid surface topology structure.One pair of additional singular point of surface topology structure ge-nerates with plasma actuation and one more reattachment line appears,which break the the separation line on suction surface at angle of attack of 2°.There are five principal vortices inside the cascade passage.The radial coupling-vortex greatly promotes the fluids carried by passage vortex to move in spanwise direction and becomes the main part of backflow on suction surface.Corner vortex exists independently and its strength and scale are hardly affected by plasma actuation.Suction surface streamwise actuation can have better effect on the flowfield near midspan than the angular region.Endwall pitchwise actuation can prevent the flow separation in corner region except for the flowfield near midspan.Combined actuation can obviously prevent the flow separation for the whole blade span.Endwall transverse movement has greater influence on flow separation structure in corner region than separated suction side boundary layer.Optimized suction side streamwise actuation obviously reduce the capability of preventing boundary layer separated flow,but the optimized endwall pitchwise actuation and combined actuation retain and enhance the performance of plasma flow control.