Passive Control of Base Pressure and the Flow Development in a Duct with Sudden Expansion at Sonic Mach Number

The primary purpose of this research is to investigate the effectiveness of rib as a passive control to control the flow development around the circular duct at different levels of expansion using Computational Fluid Dynamics (CFD). The nozzle pressure ratio (NPR), rib size, and rib orientation were considered in this research. The L/D ratio is from 3 to 5; the simulated NPRs were 1.5, 2, 3, 4, and 5. The rib was designed with a quarter circular shape to see the method's effectiveness. The focus was on the duct’s base pressure and wall pressure. The results show that the rib size and orientation strongly influenced the base pressure. The base pressure for the model with rib keeps increasing while the base pressure for the model with plain duct shows opposite results as the NPR increases. The base wall's pressure was not affected by nozzle pressure ratio only. Still, other characteristics, such as rib size and orientation, are significant in manipulating the result. However, the rib does not adversely impact the flow in the duct.