CFD Analysis to investigate the effect of axial spacing in a single stage transonic axial flow compressor

The axial spacing between the rotor and stator is an important parameter and has a strong influence on the\ud performance of axial turbomachines. A study has been carried out to verify the effect of axial spacing on the performance of 1.35 pressure ratio single stage transonic compressor stage through CFD analysis using commercial code ANSYS FLUENT. Standard k-ε turbulence model with standard wall function is used for analysis. Reynolds Averaged Navier-Stokes equations are discretized with finite volume approximations using hybrid grids. First the analysis has been carried out for the baseline configuration of the compressor stage having an axial blade spacing of 75% of the rotor tip axial chord. The steady flow computations have been carried out for four speeds namely 43%, 60%, 80% and 90% of the compressor design speed and obtained the overall performance characteristics of the compressor stage. For validation, CFD values are compared with the\ud experimental results. CFD results showed good agreement with the experiments and hence, the analysis has extended to four more axial spacing configurations such as 30%, 60%, 90% and 120% of the rotor tip axial chord. This study shows that for getting best operating conditions, the axial spacing for the referred compressor stage should lie in the range of 65 to 75% of rotor tip axial chord