Help needed Centrifugal compressor problem

Raghavendra.M

Dear friends I am raghavendra doing masters in rotating machinery design and i am in my project phase now and i am studying the effect of reduction in centrifugal blade height at the exit of the impeller.

Problem

impeller parameters outer diameter=406mm speed=23000 blade height at exit = 20.4 mm boundary condition pressure inlet pressure outlet

solver density based

viscous model k-e model realizable option

Currently i am studying the effect of 20% blade height trim in fluent the problem is as i am increasing the outlet static pressure from initial 0.5 bar to 0.75 bar the total pressure across the impeller is not rising or mass flow is not changing and i noticed that i am getting high swirl number.

can any one suggest me how can i fix this problem Any help is appreciated

Thanks Raghavendra.M