Effect of Impeller Outlet Flow Affected by Casing Treatment on Rotating Stall in Vane-Less Diffuser in Centrifugal Turbomachinery
Effect of Impeller Outlet Flow Affected by Casing Treatment on Rotating Stall in Vane-Less Diffuser in Centrifugal Turbomachinery
复制标题
套管处理对叶轮出口流量对离心式透平机械无叶扩压器旋转失速的影响
DOI：
10.1115/gt2018-76461
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Yasushi Shinkawa
中科院分区：
文献类型：
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作者：
Kazuhiro Tsukamoto;Shohei Suto;Kiyotaka Hiradate;Yasushi Shinkawa
实验研究了离心泵无叶扩压器中再循环机匣处理对叶轮出口流动的影响。
离心式压缩机需要更高的效率和更宽的工作范围。在较低的流量下，旋转失速有时会发生在无叶片扩压器中，并产生显著的次同步振动，这通常标志着实际压缩机工作曲线的极限。因此，当发生旋转失速时，应减小推力轴承和径向轴承上的振动和载荷。许多研究已经调查了旋转失速无叶扩压器在离心涡轮机。另一方面，很少有研究调查如何失速特性的变化时，机匣处理，这是一种有效的手段，扩大了离心压缩机的工作范围，实施。从这一角度出发，本研究通过实验研究了叶轮出口流动对无叶扩压器内旋转失速的影响，并评估了减小轴振动的可能性。
对两种不同的离心叶轮进行了试验研究，以考察叶轮出口流场的影响。A型叶轮出口叶片角较小，叶轮进口到出口的相对速度减速比较大。B型叶轮具有较大的出口气流角和较低的减速比。两个叶轮具有相同的锥形几何形状。
实验结果表明，这两个叶轮获得的地图宽度扩展为低流量区域的10%以上的从机匣处理。在叶轮-A的情况下，静压上升由于壳体处理而增加。然而，由于旋转失速，扩压器处的压力波动增加。另一方面，在叶轮-B的情况下，静压上升在无叶片扩压器而不是叶轮处增加。在叶轮B中，机匣处理降低了由于旋转失速引起的扩压器处的压力波动，并保持了静压上升的负斜率。结果表明，改善B型叶轮的出口流动可以减少旋转失速引起的轴振荡。
The effect of impeller outlet flow affected by a recirculating casing treatment on rotating stall in a vane-less diffuser in centrifugal turbomachinery was investigated experimentally.
Centrifugal compressors require higher efficiency and wider operating range. At lower flow rates, rotating stall sometimes occurs in a vane-less diffuser and generates significant subsynchronous vibrations, which often mark the limit of the operating curve of actual compressors. For this reason, the vibration and load on thrust and radial bearings should be reduced when rotating stall occurs. Many studies have investigated rotating stalls in vane-less diffusers in centrifugal turbomachinery. On the other hand, few studies have investigated how stall characteristics change when a casing treatment which is an effective means of expanding the operating range of the centrifugal compressor, is implemented. From this aspect, this research experimentally investigated the effect of the impeller outlet flow on rotating stall in a vane-less diffuser and evaluated the possibility of decreasing shaft vibration.
Two different centrifugal impellers with the same recirculating casing treatment were investigated to examine the effect of the impeller outlet flow field. Impeller-A had a smaller exit blade angle with a higher deceleration ratio of impeller relative velocity from inlet to outlet. Impeller-B had a larger exit flow angle with a lower deceleration ratio. Both impellers had the same meridional geometry.
Experimental results showed that both impellers obtained map width expansions for lower flow rate regions of more than 10% from the casing treatment. In the case of Impeller-A, the static pressure rise increased as a result of the casing treatment. However, the pressure fluctuations at the diffuser due to the rotating stall increased. On the other hand, in the case of Impeller-B, the static pressure rise increased at the vane-less diffuser instead of the impeller. In Impeller-B, the casing treatment decreased the pressure fluctuation at the diffuser due to the rotating stall and kept the static pressure rise with a negative slope. The results indicate that improving the outlet flow in cases such as Impeller-B may decrease the shaft oscillations due to rotating stall.