倾斜/弯曲导叶对跨声速涡轮非定常性能的影响

Effect of lean/bowed vane on the unsteady performance of transonic turbine

为探究倾斜/弯曲导叶对涡轮气动性能及非定常性的影响,采用SAS SST方法求解N-S方程组,对不同倾斜/弯曲导叶构型的跨声速涡轮级进行全三维黏性非定常数值模拟.分析倾斜/弯曲导叶对涡轮级效率及效率波动的影响,以及对导叶和下游动叶总扰动强度、各阶谐频扰动强度的影响,结合时空图将扰动与流动现象进行关联,探究导叶构型影响涡轮非定常性的机理.结果表明:正倾斜和正弯曲导叶可以有效地提升涡轮级效率,并减小涡轮级效率波动水平,使得涡轮级运行更加平稳;跨声速涡轮转子叶片上主要气动扰动来源于导叶尾缘激波在下游转子叶片上移动及反射产生的压力扰动,倾斜/弯曲导叶可以有效降低转子叶片扰动强度;正倾斜导叶主要通过影响一阶谐频的扰动强度来降低转子叶根和叶尖的总扰动强度,但叶中区域扰动强度则通过降低二阶及更高阶谐频上的扰动实现;正弯曲导叶转子叶根位置的扰动强度降低主要通过三阶谐频扰动强度降低实现,叶尖区域扰动强度的降低主要通过一阶谐频扰动降低来实现,而叶中区域的扰动强度则通过各阶谐频上扰动强度共同降低实现.

To investigate the effect of lean/bowed vane configurations on the aerodynamic performance and unsteadiness in transonic high-pressure turbine,the full three dimensional viscous unsteady numerical simulation were performed by solving N-S equations based on SAS SST method.The influence of bowed/lean vanes on turbine efficiency and efficiency fluctuation were investigated,and the action of vane modeling to the aerodynamic total perturbation level and the amplitude of each vane passing frequency were analyzed.The linking of the pressure fluctuation on blade surface with flow distortions was accomplished by comparing instantaneous pressure fluctuation contours of blade with space-time maps,which can reveal the mechanism of the influence of the vane modeling.The results indicate that the turbine efficiency is promoted with positive lean and bowed vane modeling,and the fluctuation of stage turbine is repressed,which is beneficial to the smooth running of the turbine stage.The aerodynamic disturbance on the rotor blade is dominated by the moving of vane trailing edge shock system,and the vane modeling can reduce the perturbation level on the rotor blade.For the positive lean vane,the unsteadiness at the root and tip region is reduced by the reduction of the amplitude of the first harmonic,but it is reduced by the reduction of the amplitude of second and higher harmonic at the middle region.For the positive bowed vane,unsteadiness is repressed by reducing the amplitude of third harmonic at the root region,and the first harmonic at the tip region and the amplitude of each harmonic is reduced at the middle region.