Effect of Vortex-injection Interaction on Wall Heat Transfer in a Flat Plate with Fin Corner Geometry

Effect of Vortex-injection Interaction on Wall Heat Transfer in a Flat Plate with Fin Corner Geometry

More flexible and economical access to space is achievable using hypersonic air-breathing propulsion. One of the main challenges for hypersonic air-breathing propulsion is reaching high combustion efficiency within the short residence time of the flow in the engine. Lengthening the combustor is not a viable option due to its many drawbacks, and the use of hypermixers or strut injectors increases mixing efficiency at the cost of increasing losses and heat load. On the contrary, inlet-generated vortices are an intrinsic feature of many scramjet inlets, and can be used to enhance mixing, incurring minimal losses and heat load increase. A previous computational study used a canonical geometry consisting of a flat plate with a fin at different deflection angles to investigate the ability of inlet-generated vortices to enhance the mixing rate. Significant increases in mixing rate were obtained due to the vortex-fuel plume interaction. The flow conditions were equivalent to those found in a rectangular-to-elliptical shape transition scramjet inlet at a Mach 12, 50 kPa constant dynamic pressure trajectory. Despite the minimal heat load increase of this approach, characterization of the vortex-fuel plume interaction effect on the wall heat transfer is required. In this work, the previous study is extended, describing the effect of the vortex-fuel plume interaction on wall heat transfer. Heat flux in the vicinity of the porthole injector reaches 200% compared to the baseline case with no vortex interaction. Moreover, the injection bow shock affects the corner region, creating pockets of heat flux up to 75% larger than the unaffected region. Additionally, the evolution of the fuel plume downstream of the injector location is investigated, describing the relationship between local maxima and minima of heat flux, and the location of the fuel on the wall surface. This relationship can be exploited in experimental data acquisition to obtain the fuel location from heat flux data. The viability of this experimental approach is explored using computational data, confirming that through careful sensor placement, position measurements with an accuracy higher than ±5mm can be achieved.

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