背腔结构对双级离心空压机轴向力及性能影响

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.