CFD analysis of flow fields for shrouded wind turbine’s diffuser model with different flange angles

Abstract

The present study shows a development and analysis of 2-D axisymmetric CFD model of flanged diffuser that was used as a casing for developed small wind turbines to increase the generated power. The 2-D CFD diffuser model grids are developed by GAMBIT, while the flow field analysis has been carried out using commercial software FLUENT. This study focuses on the effect of flange’s angles as a varied parameter on velocity at diffuser entrance. All models have the same dimensions in diffuser length, entrance diameter, exit diameter and flange height but differ in flange angle. Flange angles of these tested models vary from −25° to +25°, where flange angles were measured to vertical axis. Present model verification indicates a good agreement between present numerical work and previous published experimental work. The numerical simulation shows the created vortices behind flange that cause pressure drop which increases mass flow rate through the diffuser. The results indicate also that the right flange angle at 15° is the optimum angle that accelerates flow at diffuser entrance. The increase of velocity at this optimum flange angles is higher than the case of normal angle, where the expected increase in the generated power by wind turbine can reach 5% more compared with normal flange.