离心叶片进出口几何形状对气动性能影响研究

Impact of Inlet and Outlet Geometry of Centrifugal Blade on Aerodynamic Performance

为研究叶片进出口几何形状对离心叶轮内部流场及气动性能影响,以某离心叶轮为研究对象,对叶片进出口前、尾缘分别进行不同尺寸修圆处理,采用SSTk-ω湍流模型与High Resolution数值方法进行周期性单流道数值模拟,研究了叶片不同尺寸进出口前、尾缘修圆产生的几何形状对离心叶轮内部流场分布和气动性能的影响。研究结果表明:叶片进口前缘平凸形修圆能够增加离心叶轮总压比和多变效率,减少气流在进口前缘局部流动分离损失;平凸形修圆尺寸越小,多变效率和总压比增加越明显,在设计工况点二者最大增加约1%;叶片尾缘压力面修圆能够增加离心叶轮的多变效率,但降低了离心叶轮的总压比,而尾缘吸力面修圆能达到同时增加离心叶轮多变效率和总压比的目的,使得设计工况下多变效率最大增加约1%,总压比最大增加约5%,且减少了气体流出叶轮时的尾迹损失。对叶片前缘小尺寸平凸形修圆和尾缘吸力面的大尺寸修圆,不仅能减少叶片进出口局部流动损失,而且能使设计工况点多变效率增加约1.5%,总压比增加约7%,从而提高离心叶轮的做功能力,为离心叶片设计优化和高效加工制造提供了参考。

To study the impact of the blade inlet and outlet geometry on the internal flow field and aerodynamic performance of the centrifugal impeller,the leading and trailing edges of the blade-inlet and outlet were respectively rounded with different dimensions on a centrifugal impeller taken as the research object.The SST turbulence model and the High Resolution numerical method were used for periodic single channel numerical simulation of the centrifugal impeller,and the impact of the geometric shape produced by the rounding with different dimensions of the leading and trailing of the blade on the internal flow field distribution and aerodynamic performance of the centrifugal impeller was studied in this paper.The results showed that the flat-convex rounding of the leading edge of the blade inlet can increase the total pressure ratio and polytropic efficiency of the centrifugal impeller,and reduce the local flow separation loss at the leading edge of the inlet.The smaller the size of flat-convex rounding,the more obvious the increase of polytropic efficiency and total pressure ratio,and the maximum increase of both was about 1%at the design operating point.Rounding the pressure surface at the trailing edge of the blade can increase the polytropic efficiency of the centrifugal impeller,but reduce the total pressure ratio of the centrifugal impeller.Rounding the suction surface at the trailing edge can simultaneously increase both the polytropic efficiency and the total pressure ratio of the centrifugal impeller,making the maximum polytropic efficiency increase by about 1%and the maximum total pressure ratio increase by about 5%under the design condition,and reducing the wake loss when the air flows out of the impeller.The flat-convex rounding of the blade leading edge in small size and of the trailing edge suction surface in large size can not only reduce the local flow loss at the inlet and outlet of the blade,but also increase the polytropic efficiency by about 1.5%and the total pressure ratio by about 7%at the design operating point.Furthermore,it can improve the performance of the centrifugal impeller,providing a reference for the design optimization and efficient machining and manufacturing of the centrifugal blade.