BASE FLOW CONTROL THROUGH A TRIANGULAR CAVITY WITH SUDDEN EXPANSION AT SUPERSONIC MACH NUMBER FOR LOWER AREA RATIO

Source abstract

This investigation examines passive control tactics for administering base pressure at Mach M = 1.8. Because the base pressure in the separated section is reduced and below the back pressure, it contributes a sizable portion of the total drag. Hence, we must restrain or regulate this parameter. Consequently, we use base drag to extend the range of aerospace vehicles and save energy. We select expansion levels to expose the nozzle to both adverse and favorable pressure conditions, allowing us to evaluate the control mechanism's efficacy. We select three cavity geometries to evaluate the flow-regulation mechanism by placing the cavities at various positions across a range of duct sizes. The simulated results show that the cavity is effective only when the viscous layer exiting the nozzle enters the cavity; otherwise, the control is ineffective, regardless of whether the reattachment point occurs before or after the cavity. The present investigation shows that the cavity is most effective when located 8.5 mm from the base; however, at other cavity locations, its effectiveness is negligible except at NPRs 3 and 5. At these two NPRs, the exiting flow is associated with oblique shock waves and an adverse pressure gradient, which reduces base pressure.