叶顶间隙对离心叶轮内部流动及气动性能的影响

通过求解 N- S方程 ,数值研究了叶顶间隙对 NASA低速大尺度离心压缩机 (L SCC)三维粘性流场及气动性能的影响 ,在计算程序中采用了当地时间步长、多重网格以及隐式参差光顺来进行加速。对具有 0 .0 % ,5 0 % ,10 0 % ,2 0 0 %倍设计间隙的 4种离心叶轮的流场及气动性能进行了数值预测。研究结果表明 (1) NASA低速大尺度离心压缩机 (L SCC)半开式叶轮的低速尾迹区在压力面与轮盖的角区 ,而相应的闭式叶轮的低速尾迹区聚集在轮盖的中心位置 ;(2 )数值实验表明 ,叶顶间隙并非越小越好 ,可能存在一个最优间隙 ,使得叶轮流动损失最小

Influence of Tip Clearance on the Flow Field and Aerodynamic Performance of the Centrifugal Impeller

This paper studies numerically the influence of the tip clearance on the three dimensional viscous flowfield and performance of the NASA Low Speed Centrifugal Compressor (LSCC) impeller with a vaneless diffuser A three dimensional viscous code developed by the authors is applied with several acceleration methods: local time step, multigrid and residual smoothing The computations were performed under several operating conditions with four different tip clearance sizes(0 0%,50%,100% and 200% design tip clearance) The numerical results show that: (1) the throughflow wake is considerably influenced by the tip clearance The low kinetic energy fluid accumulated in the shroud/pressure side of the unshrouded impeller, but in the shroud/suction region for 0 0 tip clearance; (2) there possibly exists an optimum size of the tip clearance which is not the zero tip clearance to make the flow loss minimized