中文摘要：

对采用无叶扩压器、叶片扩压器以及串列叶片扩压器的车用增压器离心压气机内部流动进行了数值分析，研究了不同扩压形式对压气机性能的影响。结果表明，低稠度叶片式扩压器在设计工况点附近可以有效提高压气机效率；串列式叶片扩压器则可以改善叶片扩压器流量范围减小的问题。在小流量工况下，气流角与设计工况不同，攻角增大，使得流动分离加剧，损失变大。通过调节叶片安装角可以减小气流攻角，改善压气机性能。基于本文研究结果，可以为全可调离心压气机的设计和调节策略的研究提供理论依据。

英文摘要：

Numerical study on a turbocharging centrifugal compressor with vaneless, vane and tandem vane diffuser are carried out to investigate the influences of diffuser types on the compressor performances. Results show that low solidity vane diffuser can increase the compressor efficiency near design point with certain loss in stability range. With the use of tandem diffuser, efficiency and stability range can be further improved upon vane diffuser. Results also indicate that under off-design point near surge, large flow attack angle leads to big separation and flow losses, which can be effectively improved by variable diffuser. These results can supply theoretics for the design and fully adjustable strategy of centrifugal compressor.