低雷诺数下低压涡轮叶片振动对分离及转捩的影响机制

Influence mechanism of low-pressure turbine blade vibration on separation and transition at low Reynolds number

低压涡轮叶片振动显著影响边界层演化过程和流动状态,进而影响气动性能。为了探究低压涡轮叶片振动对分离转捩的影响机制,利用数值模拟手段对比分析了低雷诺数(Re=25000)下低压涡轮叶片不同频率的振动对吸力面边界层分离及转捩和流动损失的影响。研究表明:叶片因振动与流体产生的相对运动使分离流与主流提前相遇从而引发转捩提前,限制分离泡的发展,缩减分离泡的尺寸,削弱分离泡内部回流掺混。叶片振动使边界层厚度有所减小,削弱了尾缘附近的流动阻塞与尾迹掺混,大幅度降低了分离及转捩过程中的湍流脉动水平,上述变化使总压损失得到了大幅度降低,最高可以降低23.02%,气动性能得到大大改善。

Numerical simulation methods were used to compare and analyze the effects of lowpressure turbine blade vibration at different frequencies on the separation and transition of suction surface boundary layer and flow losses at low Reynolds number(Re-25000),with its aim of exploring the influence mechanism of low-pressure turbine blade vibration on separation and transition.The research showed that the relative motion between the fluid and the blade due to the blade vibration made the separation flow meet the main flow in advance.The advanced transition caused by this was able to limit the development of the separation bubble,reduce the size of the separation bubble and weaken the backflow mixing inside the separation bubble.The blade vibration thinned the boundary layer,weakened the flow blockage and wake mixing near the trailing edge and substantially lowered the turbulent pulsation level in the separation and transition process.Furthermore,the impacts above reduced the total pressure loss up to 23.02%,and improved the aerodynamic performance significantly.