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The high-enthalpy, hypersonic flow over a compression corner has been examined experimentally and theoretically. Surface static pressure and heat transfer distributions, along with some flow visualization data, were obtained in a free-piston shock tunnel operating at enthalpies ranging from 3 MJ kg−1 to 19 MJ kg−1, with the Mach number varying from 7.5 to 9.0 and the Reynolds number based on upstream fetch from 2.7×104 to 2.7×105. The flow was laminar throughout. The experimental data compared well with theories valid for perfect gas flow and with other relevant low-to-moderate enthalpy data, suggesting that for the current experimental conditions, the real gas effects on shock wave/boundary layer interaction are negligible. The flat-plate similarity theory has been extended to include equilibrium real gas effects. While this theory is not applicable to the current experimental conditions, it has been employed here to determine the potential maximum effect of real gas behaviour. For the flat plate, only small differences between perfect gas and equilibrium gas flows are predicted, consistent with experimental observations. For the compression corner, a more rapid rise to the maximum pressure and heat transfer on the ramp face is predicted in the real gas flows, with the pressure lying slightly below, and the heat transfer slightly above, the perfect gas prediction. The increase in peak heat transfer is attributed to the reduction in boundary layer displacement thickness due to real gas effects.

The synthetic jet actuator is a novel means of applying flow control that lends itself to use as part of the emerging area of micro-electro-mechanical systems. The synthetic jet flow generated by a circular orifice is investigated here using experimental and computational approaches. It is found that the synthetic jet behaves in a similar manner to a steady turbulent jet, except that it forms much more rapidly. This is a consequence of the increased entrainment of ambient fluid which arises because of the pulsatile nature of the flow. The flow achieves a pseudo-steady state because of turbulent dissipation near the jet orifice. It is observed that when the membrane forcing frequency is varied, the response as measured by the jet velocity exhibits strong peaks due to the acoustic and structural properties of the actuator. Further, the maximum velocity for a particular actuator configuration would seem to depend on a balance between inertia and viscous forces. Nomenclature b = full-width at half-maximum of jet d, = orifice diameter d, F cavity diameter f = forcing frequency h, = orifice height h, = cavity height k = turbulent kinetic energy Red= Ud/v r = radial distance from the centre-line &=fd/U r = time t*= t U,ld, U = mean velocity UC = centre-line mean velocity U, = forcing velocity (see Eqn. (1)) u' = fluctuating (RMS) velocity u,' = centre-line fluctuating (RMS) velocity y = streamwise distance from the orifice E = dissipation rate of turbulent kinetic energy w=2nf v = kinematic viscosity v, = turbulent kinematic viscosity