Turbulent Flow Analysis in an Annular Diffuser Having a Rectangular Twisted Hub

Turbulent flow characteristics through a three-dimensional annular diffuser having a rectangular twisted hub RTH are investigated. The numerical analyses are performed to have more understanding of the physical behavior of the fluid flow. The numerical work is conducted using the RTH with three twist ratios (y/w = 0.6, 0.7, and 1) for a Reynolds number 128069. In the present study, the air is used as a working fluid. Computational Fluid Dynamics CFD, based on a finite volume method, is completed by utilizing the standard k-ε turbulence model. Velocity streamlines, velocity contours, and pressure contours plots are described to study the flow characteristics by utilizing different twist ratios (y\w). The analytical results reveal that RTH has a significant effect on the velocity and pressure characteristics. Findings show that the diffuser with the twist ratio (y\w = 0.6) produces more swirling and recirculation than (y\w = 0.7 and 1). Therefore, the RTH with a small twist ratio significantly enhances the distribution of the velocity and pressure because of the strong swirling generated through the flow.