等离子体对大折转角扩压叶栅性能影响的机理

Mechanism of plasma effect on the performance of highly-turning compressor cascade

关键词:  扩压叶栅  等离子体  耗散函数  损失分析

Key words:  Compressor cascade  Plasma  Dissipation function  Loss mechanism

摘要:

利用熵和耗散函数分析了某大折转角扩压叶栅内的流动及损失特性,探讨了等离子体减小损失的作用机理。结果表明,分离区仅是低能流体聚集区,而非高损失来源区;等离子体影响叶栅流动的机制可归结为,诱导其作用区上游流体加速降压、在其作用区内构造局部顺压力梯度以及增加电极附近的气流速度;等离子体通过减弱流动分离以减小栅内损失,其本质是通过减小吸力面后半部的分离区或低速区以减弱其与主流的剪切强度和减小强剪切作用区,从而减弱该区域内的耗散;等离子作用下吸力面附近气体流速的增加使得尾迹损失减小,而电极表面附近的粘性摩擦损失增加。

Abstract:

The mechanism of plasma effect was investigated on a highly-turning compressor cascade by discussing the entropy and dissipation function.The results show that the separation zone is merely an accumulation area for low-energy fluid with large total pressure loss and entropy rather than a zone of losses source.The mechanisms of the plasma effect on the flow field are inferred to include reducing the pressure upstream the plasma region by inducing acceleration,generating a local favorable pressure gradient within the plasma region and increasing the flow velocity near the electrodes.Moreover the plasma can weaken the shear strength and reduce the strong shear zone in the region between the separation and mainstream by increasing the velocity and minishing the separation area,which is the essence of plasma effect on reducing the cascade losses.It is also found that the wake loss are reduced and the friction loss near the electrode are enhanced,which are caused by the increase of the velocity.