Generation Mechanism of Diffuser Stall in a Centrifugal Compressor with Vaneless Diffuser
Generation Mechanism of Diffuser Stall in a Centrifugal Compressor with Vaneless Diffuser
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DOI：
10.33737/gpps20-tc-59
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发表时间：
2020-09
影响因子：
0.9
通讯作者：
N. Fujisawa;K. Tajima;H. Miida;Y. Ohta
中科院分区：
文献类型：
--
作者：
N. Fujisawa;K. Tajima;H. Miida;Y. Ohta
通过实验和计算分析，研究了无叶扩压器离心压气机扩压器失速的产生机理。扩压器失速随着流量的减小而产生。扩压器失速单元以叶轮转速的25- 30%旋转，在与截止点成180°处观察到扩压器失速波动。扩压器失速波动幅度在截止点附近逐渐增大。根据CFD分析，扩压器出口处的质量流量波动显示出低质量流量区域，以约25%的叶轮转速旋转。它们开始于与截止点成180°的位置，并随着该区域接近截止点而发展。因此，可以通过CFD分析来模拟扩压器失速。首先，扩压器失速区起源于距截止点180°处，与边界分离和叶轮出口涡相互作用。然后，扩压器失速单元进一步发展，边界分离积累和诱导低速区，低速区形成横跨扩压器通道跨度的阻塞。扩压器失速区由于正气流角引起的边界分离而扩大。最后，扩压器失速单元消失时，它通过了切断，因为质量流量恢复发生。
The generation mechanism of a diffuser stall in a centrifugal compressor with a vaneless diffuser was investigated by experimental and computational analyses. The diffuser stall generated as the mass flow rate decreased. The diffuser stall cell rotated at 25-30 % of the impeller rotational speed, with diffuser stall fluctuations observed at 180° from the cutoff. The diffuser stall fluctuation magnitude gradually increased near the cutoff. According to the CFD analysis, the mass flow fluctuations at the diffuser exit showed a low mass flow region, rotating at approximately 25% of the impeller rotational speed. They began at 180° from the cutoff and developed as this region approached the cutoff. Therefore, the diffuser stall could be simulated by CFD analysis. First, the diffuser stall cell originated at 180° from the cutoff by interaction with boundary separation and impeller discharge vortex. Then, the diffuser stall cell further developed by boundary separation accumulation and the induced low velocity area The low velocity region formed a blockage across the diffuser passage span. The diffuser stall cell expanded due to boundary separation caused by a positive flow angle. Finally, the diffuser stall cell vanished when it passed the cutoff, because mass flow recovery occurred.