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

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 R e θ = 2000 - 15 000 . Under control, the separation bubble sizes or pressure coefficient C p , end at the end of the ramp exhibits a dependence on R e θ , blowing jet angle α , and jet Reynolds number R e d . It is found that, for a given α , the relationship C p , end = f 1 ( R e θ , α , R e d ) may be reduced to C p , end = f 2 ( C m ) , where C m = U j / U ∞ is the jet velocity ratio. That is, given the same C_m, C p , end remains unchanged, irrespective of different R e θ or R e d . 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.