导风轮叶片偏置对高压比串列离心压气机性能的影响

Effects of Exducer Blade Offset on Performance of High Pressure Ratio Tandem Centrifugal Compressor

关键词:  离心压气机  叶轮  叶片  流场特性  性能优化  数值仿真

Key words:  Centrifugal compressor  Impeller  Blade  Flow field characteristics  Performance optimization  Numerical simulation

摘要:

为提升高压比串列离心压气机的性能，借鉴常规一体化离心叶轮中偏置分流叶片的方法，针对某高压比串列离心压气机，应用数值仿真手段分析了串列叶轮中导风轮叶片周向偏置对压气机流场和性能的影响。通过对不同导风轮叶片偏置方案下压气机流场的分析，建立了压气机流动损失与偏置参数的关联性。研究表明：采用较大的偏置参数γ可降低导风轮叶片1前缘的激波强度，改善激波作用导致的泄漏涡破碎和流动分离，但过大或过小的γ方案中导风轮叶顶会出现二次泄漏致使低能流体的掺混损失增加；γ=65%方案压气机综合性能最佳，其压比和效率较γ=50%分别提高了1.5%和1.4%；对于串列离心压气机导风轮叶片周向位置的优化，在避免导风轮叶顶形成较强二次泄漏的前提下，应考虑采用较大的偏置参数γ，同时应防止诱导轮尾迹流体参与导风轮的叶顶泄漏。

Abstract:

The method of offset splitter blade in traditional integrated centrifugal impeller is used for reference to enhance the performance of a high pressure ratio tandem centrifugal compressor. Numerical simulation is applied to analyze the effects of the exducer blade clocking arrangement on the flow field and performance of a high pressure ratio tandem centrifugal compressor. Based on the analysis of flow fields in compressor with different exducer offset values, the relationship between compressor flow losses and offset value is established. The results show that employing larger offset parameter γ can reduce the shock intensity at exducer blade 1 leading edge, which can also improve leakage vortex breakdown and flow separation caused by shock wave. But in cases of larger or smaller offset parameter, the low energy fluid mixing loss increases due to secondary leakage flow in the exducer tip region. The compressor exhibits the best overall performance with offset value of γ=65%. The pressure ratio and efficiency for case of γ=65% are improved by 1.5% and 1.4% than those for case of γ=50%, respectively. On the premise of no appearance of significant secondary leakage in exducer tip, a high value of the circumferential offset γ is to be adopted for exducer blade clocking arrangement optimization of tandem centrifugal compressor. Meanwhile the wake fluid of inducer balde should be prevented from participating in the exducer tip leakage.