Performance optimization for two-dimensional rectangular diffuser by momentum injection using computational fluid dynamics

Abstract This article explores a non-conventional method for improvement of performance of a wide-angle two-dimensional rectangular diffuser. Computational fluid dynamics investigation has been carried out to analyse the effect of injecting momentum through a moving surface to control the boundary layer separation close to the wall of a two-dimensional rectangular diffuser. A cylinder was placed at the diffuser inlet and rotated at various speeds. It is seen that injection of momentum through the moving surface delays flow separation, thereby increasing the pressure recovery coefficient. An increase in the rotational speed of the cylinder from 1500 to 5500 rad/s improves the pressure recovery coefficient marginally. Placing another cylinder at a preidentified location and rotating both cylinders at the same speed further improves the pressure recovery. Overall improvement in pressure recovery is ∼28 per cent from 0.63 to 0.81. Besides improvement of pressure recovery, the flow distribution in the core region also improves significantly.