CPC F04C 18/084 (2013.01) [F04C 18/088 (2013.01); F04C 18/16 (2013.01); F04C 18/20 (2013.01); F04C 2240/20 (2013.01); F04C 2250/201 (2013.01)] | 16 Claims |
1. A screw compressor or expander comprising:
a female rotor including a first section having a first groove with a right-hand helical profile, a second section having a second groove with a left-hand helical profile, and a first central section having a first curved transition connecting the first and second groove; and
a male rotor including a third section having a first lobe with a right-hand helical profile, a fourth section having a second lobe with a lefthand helical profile, and a second central section having a second curved transition connecting the first and second lobes, wherein the first and second curved transitions each have a substantially rounded configuration, and wherein at least one of the first and second curved transitions includes a pocket formed in a surface of the at least one of the first and second curved transitions, the pocket configured to relieve air trapped by the at least one of the first and second curved transitions.
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