叶顶间隙对离心压气机性能影响的研究

叶顶间隙的研究长期以来一直是叶轮机械研究和设计的热点和难点。本文采用CFD软件研究了进口叶尖相对马赫数分别为0．9、1．15、1．3时,有、无间隙的离心叶轮的气动性能,比较了压比、效率及流量的差别。并分析了用于 100 kW微型燃气轮机的高压比、高转速离心压气机在三种不同尺寸叶顶间隙下的性能,讨论了间隙影响的原因。数值模拟结果表明,叶顶间隙在一定范围内时,间隙主要减弱叶轮的升压能力,基本不影响效率和阻塞流量。

STUDY ON CENTRIFUGAL IMPELLER WITH TIP CLEARANCE

This paper presents the numerical investigation on a high pressure ratio, high special speed and transonic centrifugal impeller with and without tip clearance. The transportation of low energy fluid and the secondary flow spectrum are showed. The difference between tip clearance and no tip clearance are analyzed. The results show that tip leakage flow changes the loss cause and location by comparing with no tip clearance. And the development of tip leakage flow is investigated. The numerical investigation indicates that tip clearance badly decreases the ability of enhanced pressure in comparison with no tip clearance. On the whole, the flow frame of high pressure ratio centrifugal impeller is the same as that of low pressure ratio impeller. The tip leakage flow influences the loss of layer and the loss of vortices in the corner between shroud and pressure surface. It is useful for minimizing the loss of tip leakage flow to optimumly choose the tip clearance.