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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.

为了阐明扩压器壁面边界层在扩压器旋转间隙中的作用，在不同径向位置施加了边界层吸力。由于主流流量的减小，吸力增加了起动流量，说明目前归因于逆流的解释是不充分的。进行了二维无粘非线性扩散流分析。在较小的流速下，当叶轮的涡量构成一定的模式时，出现了与实验中观察到的相似的流动模式。但与实验结果相比，其起爆条件过于严峻，且考虑表面摩擦对扩散器壁面的影响时，未发生失稳。因此，模拟的不稳定性看起来与实验观察到的不一样。从旋转失速主动控制的结果出发，讨论了旋转失速的能量平衡问题。通过在扩压器入口引入与旋转失速成一定相位关系的波动流来控制。由于旋转、失速的离散频率分量在整个扩散器中完全消失，表明控制不是由于扰动的单纯线性叠加，而是由于扰动的加入而改变了旋转失速流本身。脉动流的位移效应传递给扩压流的能量与控制的旋转失速幅值有关。结果表明，当能量为负时，振幅减小。由此定量讨论了无叶扩压器旋转失速振幅与能量平衡的关系。