Performance Comparison of Twisted Low Solidity Vaned Diffusers with Different Shapes

Computational Fluid Dynamic (CFD) analysis is conducted to improve the diffuser performance on an industrial centrifugal compressor stage. The present work is concentrated on twisted vaned diffusers(TVD) with different shapes like constant thickness flat plate (FP), cambered curved arc plate (CCAP), uncambered aerofoil (NACA 0010) and cambered aerofoil (NACA 2410). For constant thickness plates, the leading and trailing edges have been rounded to have a smooth entry and exit. The aerofoil diffuser vane is formed from a standard section profile with minor modifications at the trailing edge. The twist is given to the diffuser blade by rotation at its leading edge resulting in different stagger angles from hub to shroud. The analysis was conducted at an impeller tip Mach number of 0.35. The overall stage performance is evaluated in terms of head coefficient, stage efficiency, power coefficient of the stage and static pressure recovery coefficient of diffuser with varying flow coefficients. The TVD NACA 2410 provides best performance for the chosen compressor stage.