小展弦比叶栅非轴对称端壁造型及气动性能的数值研究

Numerical Investigations on Nonaxisymmetrical End Wall Profiling and Aerodynamic Performance of a Low Aspect Ratio Cascade

提出了基于双控制型线的非轴对称端壁造型新方法,并在某小展弦比叶栅的上下端壁上完成了非轴对称端壁造型设计.采用数值求解Reynolds-Averaged Navier-Stokes(RANS)和考虑转捩模型的SST湍流模型对轴对称端壁原始叶栅和非轴对称端壁叶栅进行了详细的流场特性分析,结果表明:所提方法可以有效减少进入叶栅通道涡的低能流体,从而抑制了通道涡的发展,减少了二次流损失.由于叶栅展弦比较小,所以非轴对称端壁会影响到整个流场,使得出口气流角在整个叶高范围内有所增大,中叶展处叶片负荷下降,型面损失减少.与轴对称端壁原始叶栅相比,非轴对称端壁叶栅效率提高了0.22%,从而验证了所提方法的有效性.

A new nonaxisymmetrical end wall profiling method based on two control curves was presented and the nonaxisymmetric end wall profiling of a low aspect ratio cascade was designed by the method. The detailed flow fields of the initial axisymmetrical end wall and the nonaxisymmetrical end wall profiling cascade were numerically investigated using the Reynolds- Averaged Navier-Stokes （RANS） and the SST turbulent model with transition effects. The results show that the nonaxisymmetric end wall reduces the low-energy fluids entering the passage vortex and thus inhibits the development of the passage vortex, resulting in the decrease in the secondary loss. The nonaxisymmetric end wall influences the whole flow field due to the low aspect ratio. The outlet flow angle increases along the whole blade span. In the midspan, the decrease in the blade loading results in the reduction of the profile loss. In addition, the efficiency of end wall profiling cascade increases by 0. 22 %, compared with that of the initial cascade. The present nonaxisymmetrical end wall profiling method is Draeticable and feasible.