In wide angle diffuser, the performance is very low because of the large transitory stall. To obtain a high performance in wide angle diffuser, a method of using an inclined screen is investigated experimentally. Varing the screen and inlet conditions, pressure recovery, velocity uniformity and turbulent level are measured at the outlet to calculate the diffuser performance. Flow field inside diffuser is also measured for the purpose of investigating the mechanism of the screen effect in wide angle diffuser.
The above measuring results lead to the following conclusions. The performance is good compared with diffusers using other control devices and strongly dependent on the screen and inlet condition. The channel between the screen and the diffusing wall plays a role as like a contraction channel. The pressure gradiant in the normal direction of the center line axis increases as increasing the distance from the diffuser inlet and the maximum pressure gradiant is presented just ahead of the screen. Because of these effects, the separated flow is reattached and stabilized.
