A transonic centrifugal compressor with a ruled-impeller (that is, impeller blades are generated by a set of points swept by a moving straight line) was used as the baseline, and the impeller blades were redesigned using non-ruled surfaces (referred to as the ‘free-form impeller’) in this study to reveal the potential of this design approach to improve the performance of high-pressure-ratio centrifugal compressors. By using the method of Computational Fluid Dynamics (CFD) simulation, the performance characteristic and the flow field inside the impeller and diffuser of the baseline compressor and the free-form one were comparatively analyzed in detail. The results show that the free-form impeller design can improve the performance of the compressor in many aspects no matter at design or off-design speeds. The barreled-sweep inducer can reduce the losses from the shock wave at design speed and extend the compressor stable operating range at off-design speeds. The positive compound-lean impeller blades can suppress the reverse flow at impeller outlet. The flow downstream of the free-form impeller was also improved due to a more uniform outlet flow field provided by it at. This study aims to provide a valuable reference for applying free-form design methods to future advanced centrifugal compressors.

以具有规则叶轮的跨音速离心压缩机（即叶轮叶片由移动直线扫过的一组点生成）作为基线，并使用非规则表面重新设计叶轮叶片（称为本研究中的“自由形式叶轮”）揭示了这种设计方法在提高高压比离心压缩机性能方面的潜力。采用计算流体动力学（CFD）模拟的方法，对基准压气机和自由式压气机的叶轮和扩压器内部的性能特性和流场进行了详细的对比分析。结果表明，无论是在设计速度还是非设计速度下，自由形式的叶轮设计都可以在多个方面提高压缩机的性能。筒形扫掠诱导器可以在设计速度下减少冲击波的损失，并在非设计速度下扩大压缩机的稳定运行范围。正复合稀薄叶轮叶片可以抑制叶轮出口处的逆流。自由形式叶轮下游的流动也得到了改善，因为它提供了更均匀的出口流场。本研究旨在为未来先进的离心压缩机应用自由形式设计方法提供有价值的参考。