中文摘要：

为了深入了解不同叶顶间隙下低速离心叶轮性能变化及尾缘附近流场变化，利用商用计算流体力学软件包NUMECAFINE／TURBO分别对0．5、1、2倍叶顶间隙的LSCC离心叶轮内部三维粘性流场进行了数值模拟研究。结果表明：随着叶顶间隙的增加，叶轮通道内损失增大，尾迹损失增大，离心机的效率压比降低；随着叶顶间隙的增加，间隙泄漏流增强，通道内叶顶、机匣表面附近低速区扩大，由于尾缘附近低速区扩大并向吸力面移动，低速区与尾迹掺混加剧了叶轮出口通道涡运动，尾迹中心从压力面向通道中心移动。

英文摘要：

To better study a low-speed centrifugal impeller＇s changes in perforarmance and the near trailing edge flow field under different tip clearance, the three-dimensional viscous internal flow was numerically simulated by using of CFD software package NUMECA FINE / TURBO for analyzing the LSCC centrifugal impeller with respectively, 0.5,1,2 times tip clearance. The numerical results show that with the increasing of the tip clearance, the impeller channel loss increases, wake loss increases, the efficiency and the pressure ratio of the centrifugal decrease; with the increasing of the tip clearance, the gap leakage enhances, the low speed zone of the channel near the tip and the case surface expands, the low velocity zone near the tailing edge expands and moves to the suction side, the mixing of the low speed zone and the wake exacerbates the vortex of the channel outlet, and the wake centre moves from the pressure side to the suction side.