Effect of Diffuser Angle on the Reattachment Point of an Incompressible Airflow

Abstract

Numerical Simulation of the two dimensional incompressible airflow in an asymmetric diffuser using one commercially available Computational Fluid Dynamics (CFD) code are reported. The subject is to analyze the effect of diffuser angle on the reattachment point of air flow. Results are presented varying diffuser angle from 2 degree to 20 degree. The mathematical model equations (mass conservation and momentum) are solved using finite volume methods (FVM) and a pressure based approach. To get the grid independent, intensive refinement studies were carried out. Results obtained were compared to experimental data presenting a good agreement. The numerical results of this work show that as the diffuser angle elevates, the flow recirculation region also increases. When there are flow recirculation regions, the value of turbulent kinetic energy also increases. Hence, it is possible identify a need for improvement the design of diffuser or other alternatives to reduce the size of recirculation region, reducing the power necessary at the flow machine to realize the work at the diffuser.