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Flow Control of Vaneless Diffuser Rotating Stall

无叶扩压器旋转失速的流量控制

基本信息

批准号：
02650134
负责人：
TSUJIMOTO Yoshinobu
金额：
$ 0.32万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

In order to elucidate the role of the diffuser wall boundary layers in diffuser rotating stalls, boundary layer suction was applied at various radial locations. The onset flow was increased by the suction owing to the decrease in the main flow rate, showing that the current explanation attributing to the reverse flow is not adequate.A 2-D inviscid, nonlinear diffuser flow anaysis was made. At smaller flow rates, flow patterns similar to that observed in experiments appeared when the vorticity from the inpeller constitutes a certain pattern. However, the onset condition is too severe compared with experiments and the instability did not occur when the effects of skin friction on the diffuser wall was taken into account. Thus, the simulated instability looks to be different from those observed experimentally.Discussions on the energy balance of rotating stall were made from the results of an active control of the rotating stall. The control was made by introducing a fluctuating flow at the diffuser inlet, which is in a certain phase relation with the rotating stall. Discrete frequency component due to rotating, stall completely disappeared in the whole diffuser indicating that the control is not due to a mere linear superposition of the disturbance but the rotation stall flow itself is changed by the addition of the disturbance. The energy transferred to the diffuser flow by the displacement effect of the fluctuating flow was related with the controlled rotating stall amplitude. It was shown that the amplitude decreased when the energy is negative. From this result, the quantitative discussion was made as to the relation between the amplitude and the energy balance of vaneless diffuser rotating stall.

为了阐明扩压器壁边界层在扩压器旋转失速中的作用，在不同的径向位置施加边界层抽吸。由于主流量的减小，吸气增加了起始流量，说明现有的关于反向流动的解释是不充分的。在较小流量下，当叶轮涡量构成一定的流型时，出现了与实验中观察到的流型相似的流型。然而，与实验相比，该起稳条件过于苛刻，并且当考虑扩压器壁面摩擦力的影响时，不发生失稳。因此，模拟的不稳定性看起来与实验观察到的不同。根据旋转失速主动控制的结果，对旋转失速的能量平衡进行了讨论。通过在扩压器进口处引入与旋转失速有一定相位关系的脉动流来实现控制。旋转失速引起的离散频率分量在整个扩压器内完全消失，说明控制不是由于扰动的线性叠加，而是旋转失速流动本身被扰动的加入所改变。脉动流位移效应传递给扩压器流场的能量与受控旋转失速幅值有关。结果表明，当能量为负时，振幅减小。由此定量地讨论了无叶扩压器旋转失速的振幅与能量平衡的关系。