端壁合成射流对高负荷涡轮叶栅涡系结构和流动损失影响的数值研究

Numerical Investigation on Effects of Endwall Synthetic Jet on Vortex and Flow Losses in a High-Loaded Turbine Cascade

关键词:  合成射流  激励参数  主动流动控制  漩涡结构  流动损失

Key words:  Synthetic jet  Excitation parameter  Active flow control  Vortex structure  Flow loss

摘要:

为探究端壁合成射流对高负荷涡轮叶栅中涡系结构和流动损失的影响，采用非定常数值模拟方法分析了不同激励参数下合成射流对Durham叶栅流动损失的控制效果以及涡系结构和流动损失的对应关系。结果表明，合成射流减小了前缘马蹄涡和通道涡的尺度，削弱了来自相邻叶片压力面的横向涡，略微增强了壁角涡，并间接削弱了壁面涡；在无量纲幅值和频率分别为0.073和1时，控制效果最佳，总压损失系数减小约为10.72%；从控制机理上讲，合成射流加强了主流和射流下游边界层的掺混，增加了边界层动量，从而削弱了马蹄涡；合成射流影响了叶片压力面的流动分离，改变了由于分离产生低能流体的位置和范围，从而削弱了横向涡。由于漩涡的削弱，流动损失也随之减小。

Abstract:

To investigate the effect of endwall synthetic jet(SJ) on vortex structure and flow loss reduction in a high-loaded turbine cascade， unsteady numerical model of Durham cascade with SJ installed at the endwall upstream of the blade was established. A series of simulations were performed to determine beneficial excitation parameters. At the optimal excitation parameters， the influence of SJ on vortex structure and flow loss were investigated in detail and the association between them was focused on.The results indicated that the sizes of the horseshoe vortex and passage vortex were reduced; the transverse vortex originated from adjacent pressure surface were weakened; the corner vortex was slightly strengthened; the wall vortex was receded indirectly. Total pressure loss coefficient was decreased by 10.72% at the optimal excitation parameters when dimensionless excitation amplitude and frequency were 0.073 and 1， respectively. From the perspective of control mechanism， SJ enhanced the mixing of main fluid and boundary-layer fluid downstream of the jet， the momentum of boundary-layer fluid increased， so that the horseshoe vortex was weakened. SJ influenced the boundary separation at the pressure face of the blade， the region and position of low-energy fluid caused by boundary separation were changed， so that the transverse vortex was weakened. Flow loss was reduced as a result of weakened vortexes.