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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。
Numerical simulation of flow separation in high-load diffuser cascade is carried out by using the synthetic jet technology of the end wall. The mechanism and influencing factors of the loss control are discussed. The results show that the jet flow of the endwall can significantly improve the aerodynamic performance of the cascade, resulting in a maximum total pressure loss of 21.63% and a static pressure rise of 5.60%. The jet flow vortex formed by the jet promotes the momentum exchange between the endwall surface coating and the mainstream high velocity fluid through the upper wash / lower wash, impedes the migration of the vortex path to the middle of the leaf blade, weakens its spreading influence range, The momentum injection effect increases the energy of the fluid downstream of the stimulation slot, thus delaying the flow separation and reducing the cascade loss. Excitation position and jet angle are the important parameters that affect the effect of synthetic jet on the end wall. When the excitation is located near the upstream of the separation line in the corner and the jet angle is small, the flow control effect is the best. In addition, increasing jet momentum also helps enhance its ability to control flow separation.