Abstract: In order to explore the mechanism of stability improvement, numerical investigations are performed to examine the role of the self recirculation casing treatment and a recirculation device in which upstream slot is sealed in the enhancement of operational range of a centrifugal impeller with high pressure-ratio. The numerical results approve that self recirculation casing treatment not only can suspend the stall effectively but also can improve the impeller efficiency and total pressure ratio appreciably in the near of stall region. The detailed analysis of the flow field at the blade tip shows that it reduces the blade loading in the impeller tip region. And hence the velocity of tip leakage flow exiting the bleed slot becomes lower compared with that without the self recirculation device. All these effects induced by the recirculation device are considered to lead to the suppression of the extension of blockage and to contribute to the enhancement of the impeller operating range.

Key words: Centrifugal impeller; High pressure-ratio; Self recirculation; Casing treatment; Numerical analysis; Stall margin

摘要： 为了探索自循环机匣处理扩稳机理,利用全三维数值模拟方法对应用自循环上游槽封闭机匣和自循环机匣处理结构两种情况下的Krain高压比离心叶轮进行了详细研究。对比结果表明:自循环机匣处理能有效的延迟失速的发生并在近失速区域略微提高压气机的效率以及总压比。通过详细的流场分析表明:该机匣处理能有效地减小叶顶载荷,从而降低泄漏流相对速度,抑制间隙泄漏涡在叶顶通道内的发展以减小低速气流在流道内的阻塞,提高转子通道的通流能力,从而达到扩大稳定工作范围的目的。

关键词: 离心叶轮;高压比;自循环;机匣处理;数值分析;失速裕度