Boundary Layer Control for Hypersonic Airbreathing Vehicles

Abstract

Active and passive methods for tripping hypersonic boundary layers have been examined in NASA Langley Research Center wind tunnels using a Hyper-X model. This investigation assessed several concepts for forcing transition, including passive discrete roughness elements and active mass addition (or blowing), in the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air Tunnels. Heat transfer distributions obtained via phosphor thermography, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. The comparisons between the active and passive methods for boundary layer control were conducted at test conditions that nearly match the Hyper-X nominal Mach 7 flight test-point of an angle-of-attack of 2-deg and length Reynolds number of 5.6 million. For passive roughness, the primary parametric variation was a range of trip heights within the calculated boundary layer thickness for several trip concepts. The passive roughness study resulted in a swept ramp configuration, scaled to be roughly 0.6 of the calculated boundary layer thickness, being selected for the Mach 7 flight vehicle. For the active blowing study, the manifold pressure was systematically varied (while monitoring the mass flow) for each configuration to determine the jet penetration height, with schlieren, and transition movement, with the phosphor system, for comparison to the passive results. All the blowing concepts tested, which included various rows of sonic orifices (holes), two-and three-dimensional slots, and random porosity, provided transition onset near the trip location with manifold stagnation pressures on the order of 40 times the model surface static pressure, which is adequate to ensure sonic jets. The present results indicate that the jet penetration height for blowing was roughly half the height required with passive roughness elements for an equivalent amount of transition movement. Nomenclature* Aerospace Technologist, Aerothermodynamics Branch, m/s 408A, member AIAA.

Shuttle Damage/Repair from the Perspective of Hypersonic Boundary Layer Transition - Experimental Results

“…al. 41 demonstrated that mass injection from discrete orifices could successfully induce boundary layer transition consistent with that observed with the more conventional protuberance-based discrete roughness. Stalmach et.…”

NO PLIF Study of Hypersonic Transition over a Discrete Hemispherical Roughness Element

“…The ratio of the plenum pressure to plate pressure is a relevant parameter in the current experiment. Berry et al 7 found that, for slot injection, the plenum pressure needed to be 25 times higher than the plate pressure to transition the flow to turbulence within 127 mm (5.0 in) of the slot. From the data shown in Fig.…”

“…The use of a slot for seeding (as opposed to the 4 pressure ports used in Reference 3) and the choice of a flowrate of 0.3 slpm was largely based on the work of Berry et al . 7 who studied blowing-induced transition on a Hyper-X forebody model. Berry et al found that, for a given flowrate of gas, injection from a spanwise slot was the least effective method and that a spanwise row of holes was the most effective method for tripping a boundary layer to transition to turbulence.…”

Fluorescence Visualization of Hypersonic Flow Past Triangular and Rectangular Boundary-Layer Trips

“…4 In the X-43A work, schlieren flow visualization provided useful information about shock positions, although this information was path-averaged and turbulent flow structures were not identified with the schlieren. Planar laser-induced fluorescence (PLIF) is one of a variety of planar flow visualization techniques that can provide three-dimensionally spatially-resolved off-body visualizations of boundary layers 5,6,7 and other hypersonic flow phenomena.…”