Effects of Non-Axisymmetric Volute on Rotating Stall in the Vaneless Diffuser of a Centrifugal Compressor
Effects of Non-Axisymmetric Volute on Rotating Stall in the Vaneless Diffuser of a Centrifugal Compressor
复制标题
非轴对称蜗壳对离心压缩机无叶扩压器旋转失速的影响
DOI：
10.1115/gt2020-14729
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Xinqian Zheng
中科院分区：
文献类型：
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作者：
Zitian Niu;Zhenzhong Sun;Baotong Wang;Xinqian Zheng
旋转失速是离心式压气机中一种重要的不稳定流动现象，它不仅会导致压气机性能下降，而且会限制压气机的稳定边界。蜗壳是离心压气机内部非轴对称流动的诱发源之一，对压气机性能有重要影响。然而，蜗壳对旋转失速的影响尚不清楚。为此，本文通过实验和数值模拟研究了蜗壳对旋转失速的影响。结果表明，由于蜗壳引起的流场畸变，导致一个旋转失速胞在扩压器的某一特定位置产生，而在另一特定位置消失。此外，细胞不能稳定地在整个圆周上旋转。实验中捕捉到的旋转失速相关频率为叶轮通过频率的43.9%，而三维非定常数值模拟捕捉到的旋转失速相关频率为叶轮通过频率的44.7%，证明了本文数值方法的准确性。数值模拟进一步揭示了初始化在特定位置的失速胞在演化过程中可以分裂成多个胞。其原因是旋转失速引起的无叶扩压器内的堵塞被叶轮出口的主流削弱，使一个初始化的胞元分散成多个胞元。蜗壳对压气机旋转失速单元的产生和演化过程有重要影响。通过优化蜗壳几何形状，减小流场畸变，有望减弱或抑制旋转失速，有助于拓宽离心压气机的工作范围。
Rotating stall is an important unstable flow phenomenon that leads to performance degradation and limits the stability boundary in centrifugal compressors. The volute is one of the sources to induce the non-axisymmetric flow in a centrifugal compressor, which has an important effect on the performance of compressors. However, the influence of volute on rotating stall is not clear. Therefore, the effects of volute on rotating stall by experimental and numerical simulation have been explored in this paper. It’s shown that one rotating stall cell generates in a specific location and disappears in another specific location of the vaneless diffuser as a result of the distorted flow field caused by the volute. Also, the cells cannot stably rotate in a whole circle. The frequency related to rotating stall captured in the experiment is 43.9% of the impeller passing frequency (IPF), while it is 44.7% of IPF captured by three-dimensional unsteady numerical simulation, which proves the accuracy of the numerical method in this study. The numerical simulation further reveals that the stall cell initialized in a specific location can be split into several cells during the evolution process. The reason for this is that the blockage in the vaneless diffuser induced by rotating stall is weakened by the mainstream from the impeller exit to make one initialized cell disperse into several ones. The volute has an important influence on the generation and evolution process of the rotating stall cells of compressors. By optimizing volute geometry to reduce the distortion of the flow field, it is expected that rotating stall can be weakened or suppressed, which is helpful to widen the operating range of centrifugal compressors.