The multicolumn envelope meshing pair(MEMP) is the important factor that affects the performance of single screw compressor due to its complex three-dimensional structure.In order to study the working characteristic of the single screw compressor with MEMP

a geometric features numerical calculation model is set up.By using this mathematical model

the effects of the MEMP and the straight line envelope meshing pair(LEMP) on the geometric features and the thermal dynamic performances are compared.Analysis results show that the use of the MEMP makes the actual star-wheel tooth width changing along with the star-wheel angle larger than that of the star-wheel with LEMP.Affected by the change of star-wheel tooth width

the working chamber volume of the compressor with MEMP will increase

the cavity internal pressure will decrease at the same star-wheel angle

and the largest base volume will be increased 5.2%.The closed spiral will be closer to the inlet side and the exhaust orifice spiral will be closer to the exhaust end for the compressor with MEMP which will lead to the delay of the exhaust process and more flow resistance losses.All analysis results obtained can provide the theory basis for optimum design of the single screw compressor with multicolumn envelope meshing pair.