M. Godfrey Mungal

CFD aided development of an experimental setup to investigate internal supersonic combustion

The work presented here summarizes our efforts on the development of a simplified model scramjet combustor to investigate supersonic mixing and combustion in the Stanford Expansion Tube Facility. The system is designed to replicate the conditions and the flow features found in a generic scramjet engine of a hypersonic vehicle. The initial conceptual design was aided by two-dimensional numerical simulations which were targeted to identify possible working configurations, limits of operation and to isolate selected cases of interest. A configurable prototype was then developed, built and tested in our flow facility under realistic aerothermodynamic conditions of hypersonic flight. Finally, more detailed RANS numerical simulations of two representative scramjet model combustors have been undertaken. Besides identifying a suitable RANS solver for further investigations, the goal was to investigate the flowfield within the combustor and to identify the effective conditions of operations for future work.

Separation Control Using Dielectric Barrier Discharge-Induced Suction and Vortex Generation

We investigate the characteristics of vortices induced by spanwise forcing using a streamwise oriented dielectric barrier discharge (DBD) with and without a boundary layer suction channel, the flow of which is also driven by a DBD. The velocity field over various regions in the vicinity of the actuator is obtained by ensemble averaging particle image velocimetry. Increased boundary layer thinning and a stronger downward motion are seen near the powered flow-exposed electrode when the DBD is used in conjunction with a suction slot. The effect of varying the applied voltage and freestream velocity on the induced flow is examined. Studies are carried out on the ability for such a structure to control separation on an inclined flat plate and ramp. We find that DBD actuation together with boundary layer suction leads to more robust separation control in these adverse pressure gradient configurations.