背腔结构对双级离心空压机轴向力及性能影响

基于高速电机直驱与空气轴承技术的无油离心空压机增压技术在燃料电池进气系统中有着广阔的应用前景。由于空气轴承的轴向承载能力与止推轴承效率成反比,控制和减小空压机轴向推力对于提升空压机工作可靠性及运行效率至关重要。以燃料电池双级离心空压机为研究对象,设计了不同叶轮背腔模型,采用数值方法,研究轴隙泄漏、背腔轴向间隙对空压机性能及轴向力的影响。结果表明,在轴隙泄漏的影响下,背腔结构对轴向推力产生显著影响,且随着轴隙泄漏量增加,背腔结构的影响加剧。在双级结构下,高压级压气机背腔结构的变化对总体轴向推力的影响占据主导作用,通过合理的背腔结构设计并结合背腔密封技术,可有效实现对空压机轴向推力的控制,并减小轴隙泄漏对空压机性能带来的负面影响。

The Influence of Back Cavity Structure on Axial Force and Performance of Two-stage Centrifugal Compressor

The Oil-free centrifugal compressor based on high-speed direct drive motor and air bearing technology has clear application prospects in fuel cell air intake system.Since the mechanical efficiency of the air thrust bearing is inversely proportional to the axial thrust load,the control and balancing of the axial thrust exerted on the rotor can improve the working reliability and operating efficiency of the air compressor significantly.With different designs of the back cavity structure,the influence of the shaft clearance leakage and axial gap on the axial thrust and performances of the centrifugal compressor was numerically investigated.Results show that due to the influence of the shaft clearance leakage,the back cavity structure has a significant impact on the axial thrust.For the two-stage compressor investigated in current study,the change of the back cavity structure of high pressure stage has a dominant effect on the overall axial thrust.With proper design of the back cavity and sealing technology,the axial thrust can be effectively controlled and the negative influence of shaft clearance leakage on the performance of the compressor can be mitigated.