Control of flow separation from a curved ramp using a steady-blowing jet

Abstract

This work experimentally investigates flow separation control over a two-dimensional curved ramp using a spanwise steady-blowing slit jet. The flow separation and reattachment are first characterized in the absence of control for the momentum-thickness-based Reynolds number Reθ=2000–15 000. Under control, the separation bubble sizes or pressure coefficient Cp,end at the end of the ramp exhibits a dependence on Reθ, blowing jet angle α, and jet Reynolds number Red. It is found that, for a given α, the relationship Cp,end=f1 (Reθ, α, Red) may be reduced to Cp,end=f2(Cm), where Cm=Uj/U∞ is the jet velocity ratio. That is, given the same Cm, Cp,end remains unchanged, irrespective of different Reθ or Red. It is further found that flow separation from the ramp may be completely suppressed given a small α, i.e., α≤55°, but not when α is large, i.e., >85°. The corresponding mechanisms behind are discussed in detail.