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This work uses an immersed-boundary method to simulate the effects of arrays of discrete bleed holes in controlling shock-wave/turbulent-boundary-layer interactions. Both Reynolds-averaged Navier-Stokes and hybrid large-eddy/Reynolds-averaged Navier-Stokes turbulence closures are used with the immersed-boundary technique. The approach is validated by conducting simulations of Mach 2.5 flow over a perforated plate containing 18 individual bleed holes. Computed values of discharge coefficient as a function of bleed plenum pressure are compared to experimental data. Simulations of an impinging-oblique-shock/boundary-layer interaction at Mach 2.45 with and without bleed control are also performed. For the studies with bleed, two different bleed rates are employed. The 68 hole bleed plate is rendered as an immersed object in the computational domain. Wall pressure predictions show that, in general, the large-eddy/Reynolds-averaged Navier-Stokes technique underestimates the upstream extent of axial separation that occurs in the absence of bleed. Good agreement with pitot pressure surveys throughout the interaction region is obtained, however. Flow control at the maximum-bleed rate completely removes the separation region and induces local disturbances in the wall pressure distributions that are associated with the expansion of the boundary-layer fluid into the bleed port and its subsequent recompression. Computed pitot pressure distributions are in good agreement with experiment for the cases with bleed. Swirl-strength probability density distributions are used to estimate the evolution of turbulent length scales throughout the interaction. These, along with Reynolds-stress predictions, indicate that an effect of strong bleed rates is to accelerate the recovery of the boundary layer toward a new equilibrium state downstream of the interaction region. Nomenclature a 1 = model constant for Menter baseline model C f = skin-friction coefficient C M = model constant for mixed-scale model C = model constant for Menter baseline model D = diameter of bleed hole d = distance from nearest-wall/immersed-surface point d ; = normalized distance F 2 = model constant for Menter baseline model f, g = scaling functions G = Heaviside step function based on signed distance function k = turbulent kinetic energy/power law L = length of bleed hole M = Mach number n = coordinate normal to immersed surface P = static pressure P t = pitot pressure Q = sonic flow coefficient or discharge coefficient q 2 = estimate of subgrid kinetic energy R = universal gas constant Re = Reynolds number R n1;l i = residual vector at cell i for time step n 1 and subiteration l r = recovery factor S = characteristic filtered rate of strain T = temperature u = velocity vector, x component of velocity u = friction velocity V = primitive variable vector v = component of velocity in y direction w = component of velocity in z direction X = streamwise distance from leading edge of bleed-plate insert x = streamwise distance from leading edge of computational domain Y = ...

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A new geometry of a sub-boundary-layer vortex generator, which is termed as a slottedramp vortex generator, is proposed here. The geometry of the vortex generator is that of a ramp (triangular wedge) which has a semi-circular groove at its base. The centerplane of the groove or slot, which is basically like a tunnel that runs across the length of the ramp, is located at the spanwise plane of symmetry of the ramp. Preliminary computations of supersonic flow at a free-stream Mach number of 2.5 are conducted over vortex generators 2 mm, 3 mm, and 4 mm high. For each device height h, the flow is simulated for three values of the slot radius -0.2h 0.3h, and 0.4h. The incoming flow profile is based on the experiments conducted by Dr. Babinsky at Cambridge on control of shock/boundarylayer interaction with micro vortex generators at a free-stream Mach number of 2.5. An immersed-boundary technique suitable for high-speed turbulent flows is used for rendering the vortex generators. Comparisons are presented between the different slotted-ramp vortex generators with a standard ramp based vortex generator of the same device height using streamwise velocity profiles at different locations downstream of the device. Velocity plots show that the new device results in higher streamwise velocity along the centerline in the near wake region for the larger sized vortex generators and the effect improves when a higher slot radius is used. Comparisons are also presented with the standard ramp type vortex generator using span-averaged total pressure profiles and momentum-deficit contours at different streamwise locations, and near surface axial velocity contours. Finally, results from computations of an impinging oblique-shock/boundary-layer interaction for a flow turning angle of 7 degrees at Mach 2.5 with and without flow control are presented. To achieve flow control two different cases are considered -one using an array of 3 x 3 mm high slotted-ramp vortex generators and the other using a similar array of the ramp type vortex generator. All the computations done as part of this study solves the Reynoldsaveraged Navier-Stokes equations with Menter's k − ω/k − turbulence model (baseline or SST formulation).Nomenclature h height of vortex generator r slot-radius of vortex generator x streamwise distance measured from the inflow plane of computational domain X streamwise distance measured from the trailing edge of vortex generator y, Y vertical distance measured from lower wall of computational domain Z spanwise distance measured from centerplane of computational domain