The influence of low-solidity and slotting combined treatment method of diffuser vanes on performance of centrifugal compressor

Abstract

Centrifugal compressor with vane diffuser has high aerodynamic efficiency and narrow stable operating range, and study of extending its operating range has been a key and difficult point in the researching field of centrifugal compressor. In this paper, low-solidity treatment of diffuser vane is firstly adopted for a centrifugal compressor with vane diffuser, based on which slotting treatment at hub side of diffuser vane was further implemented, and then influence of this combined diffuser treatment method on the range of compressor stable operation is investigated. Results show that low-solidity treatment for diffuser vane can extend the compressor choking boundary in the full speed range and has no obvious improvement for the surge boundary; after further slotting treatment at hub side, both surge boundary and choking boundary of the compressor both increase obviously. With the increase in rotating speed, the extending effect of the stable operation range is more obvious, but this is also accompanied by an increase in aerodynamic loss. The combination treatment method of low solidity and slotting on vane hub side can be more than doubled in the stable operating range at high rotating speeds, and the effect is slightly worse at low and medium speed, compared to the vaneless diffuser treatment. Efficiency of vane diffuser compressor under low-solidity and slotting treatments can be higher than that of vaneless compressor through reasonable design of slots structure.