时序效应对涡轮叶片非定常作用力影响的数值研究

为了研究时序效应对尾迹传递及其与下游叶片排的作用机理,利用基于密度修正的求解雷诺平均N-S方程的商用CFD软件对某一1.5级轴流低压涡轮级进行了详细数值模拟。通过调整第二级导叶的周向位置来产生时序效应,结合叶片中径处的静压系数分布来详细分析时序效应对涡轮叶片非定常力的影响。结果表明:时序效应对涡轮效率影响很小,涡轮最大和最小气动效率之间相差0.1%,当进口导叶尾迹撞击出口导叶前缘时涡轮效率最小;时序效应对动叶表面中径处压力分布影响不大,对出口导叶影响较大,压力分布改变的主要原因包括尾迹的对流传递及其撞击引起叶片环量改变;时序效应对涡轮出口导叶气动力分布影响较大,相对最大效率,最小效率下的气动负荷系数和方位角要大。

Numerical Simulation of Clocking Effect on Turbine Blade Unsteady Force

To get insight into the clocking effect on the wake transportation and its interaction,the unsteady three-dimensional flow through a 1.5-stage axial low pressure turbine is simulated numerically using a density-correction based,Reynolds-averaged Navier-Stokes equations commercial CFD code.The 2nd stator clocking is applied over ten equal tangential positions.The turbine flow field is analyzed in details according to the distribution of turbulent kinetic energy and wall strain stress in the outlet stator.The results show that the clocking effect has little effects on the turbine efficiency in this investigation.The efficiency difference between the maximum and minimum configuration is nearly 0.1%.The minimum efficiency appears if the 1st stator wake impinges upon the leading edge of the 2nd stator.The clocking effect has little influence on the unsteady pressure in the rotor,neither does the 2nd stator.The main causes of pressure variation include the wake transportation and the circulation variation brought about by the wake impingement.The clocking effect has greater influence on the aerodynamic force of the 2nd stator.The effect of aerodynamic load factor and azimuth angle in minimum efficiency is greater than that in maximum efficiency.