端壁合成射流对高负荷扩压叶栅损失特性的影响

Effects of Endwall Synthetic Jet on Loss Characteristics of a Highly Loaded Compressor Cascade

关键词:  端壁合成射流  高负荷扩压叶栅  损失特性  气动性能  流动控制

Key words:  Endwall synthetic jet  Highly loaded compressor cascade  Loss characteristics  Aerodynamic performance  Flow control

摘要:

利用端壁合成射流技术对高负荷扩压叶栅内的流动分离控制展开数值研究，探讨其改善损失的作用机理及影响因素。研究结果表明，端壁合成射流可以显著提升叶栅气动性能，使总压损失最大降低21.63%，静压升提高5.60%。射流形成的流向射流旋涡通过上洗/下洗作用促进了端壁附面层与主流高速流体间的动量交换，阻碍了通道涡向叶展中部的迁移、削弱其展向影响范围，并通过流向动量注入效应增大了激励缝下游流体的能量，从而推迟流动分离、降低叶栅损失。激励位置和射流角度是影响端壁合成射流作用效果的重要参数，当激励位于角区分离线上游附近且射流角度较小时，流动控制效果最佳。此外，提高射流动量也有助于增强其控制流动分离的能力。

Abstract:

Numerical investigations for flow separation control were conducted on a highly loaded compressor cascade using endwall synthetic jet. The mechanism by which the actuation delays flow separation and reduces losses was explored and the effects of some dominant factors on the control effectiveness were analyzed in detail. Numerical results indicate that the endwall synthetic jet is able to improve the cascade aerodynamic performance remarkably，the total pressure loss could be reduced by 21.63% with a 5.60% static pressure rise increase. The streamwise jet vortex could enhance the momentum exchange between the sidewall boundary layer and the high momentum freestream fluid through upwash and downwash，which also impedes the migration of passage vortex towards the blade midspan and weakens its influence in spanwise direction. Moreover，the streamwise momentum addition by the jet could increase the energy level of the fluid downstream of the slot. The combined effects delay flow separation and reduce flow losses. Both actuation location and jet angle are important parameters for flow separation control. When the actuation is located in the near upstream of the corner separation line with a relatively small jet angle，the flow control system appears to be most efficient. Furthermore，the increase of jet momentum could also enhance its control effect on flow separation.