Book Description
In an effort to develop hypersonic air-breathing propulsion systems wavy walls were added to a cantilevered ramp injector to increase the fuel/air mixing in a shock-induced combustion ramjet (shcramjet) engine. Numerical studies of various wavy wall configurations in the vicinity of the cantilevered ramp injector were undertaken using three-dimensional, multispecies Navier-Stokes solvers. Laminar simulations established the amplitude of the wavy walls has a much greater influence upon the resulting flow field than the wall wavelength. The mixing initially increases with amplitude and then decreases as the shocks formed from the wavy wall disrupt the main mixing vortices in the flow. The addition of wavy walls allows for an increase in mixing efficiency of approximately 10%, but in the best case incurs the same degree of losses. Subsequent turbulent studies demonstrated similar flow fields to the laminar cases, with greater the mixing due to increased diffusion, but at the cost of greater losses. As such the mixing efficiency vs. total pressure loss ratios found in the turbulent cases are worse than those found in the laminar cases. It was also found that the effect of the wavy wall is reduced with increasing boundary layer height, but the mixing is augmented due to greater dissipation in the slower flow. This study suggests the addition of wavy walls to cantilevered ramp injectors may not be desired, since they do not provide a significant benefit with minimal detrimental effects.
