Control of flow separation over an axisymmetric flared body using ramped vanes

Experiments were performed at Mach 2 to assess the effectiveness of Ramped Vanes (RVs) in delaying the onset of shock-induced flow separation due to an axisymmetric compression corner. A cone-cylinder-flare model with a 24 degrees flow deflection angle at the cylinder/flare juncture was selected for this study. A single row of RVs was placed 50 mm (10 delta) upstream of the compression corner, to manipulate the incoming boundary layer and thereby bring alterations to the shock-boundary layer interaction flowfield. RVs with three sub-boundary layer heights viz. 1.4 mm, 2.1 mm and 2.8 mm (h/delta(RV) = 0.33, 0.50 and 0.67 respectively) were employed and their separation control performance was compared. Counter-rotating vortices originated from these devices, generating alternate upwash and downwash bands within the boundary layer. When the shorter devices were used, early and delayed onset of separation were noticed along the upwash and downwash regions respectively. However, as the devices grew taller, the increase in separation length along the upwash region seemed to diminish. Ultimately, when the tallest devices (h = 2.8 mm) were introduced, the entire corrugated separation line was successfully pushed downstream of the uncontrolled separation line. Besides instigating these variations in the separation scale, the vortices also caused topological changes within the separation region. But, despite achieving a substantial delay in separation, the RVs were unable to shift the separation shock's oscillations to higher frequencies. (c) 2022 Elsevier Masson SAS. All rights reserved.

Automated summary

Experiments conducted at Mach 2 demonstrated the effectiveness of Ramped Vanes (RVs) in delaying shock-induced flow separation. By manipulating the incoming boundary layer, RVs generated counter-rotating vortices that altered the flowfield, resulting in a delayed onset of separation. The height of the RVs played a significant role, with taller devices yielding a more pronounced reduction in separation length.