STUDY OF TABS IN A SHORT ANNULAR DIFFUSER WITH A STRONG SWIRLING FLOW

Passive augmentation devices are typically added to diffusers to increase pressure recovery; however, applications such as infrared suppression exist where more uniform outlet velocity profiles are also desirable. Square tabs were added to a short annular diffuser system with diffuser effectiveness of 80% in strong swirling subsonic turbulent flow. The number, axial position, width, and height were varied for the tabs with a 135 orientation angle. Results showed that back pressure increased linearly with increasing tab projected area blockage but outlet velocity uniformity was maximum with 7% tab blockage. Tabs placed on the centre body base recovered more dynamic pressure than tabs placed downstream on the centre body with similar tab area blockage.