Dynamics of elevated dodecane jets in crossflow at supercritical pressures

In advanced aero-engines, kerosene is often injected into combustor at supercritical pressures, where the shorter jet penetration depth may result in poor mixing and the resultant reaction spots near the combustor wall can cause erosion. Elevating the jet nozzle is proposed to remedy these issues. The flow dynamics of elevated dodecane jets in oxygen crossflow (EJICF) at supercritical pressures are numerically investigated using large eddy simulation. The effects of ambient pressure and elevation stack thickness and height on EJICF are studied. Results reveal that at low supercritical pressure, notable real-fluid effects arise due to density stratification in the jet's upstream shear layer, thereby delaying the shift of the flow from transitional regime to jet-dominated regime. Increasing stack thickness mitigates the impact of jet upshear effects and has the potential to eliminate lock-in phenomena between jet wake and stack wake. Decreasing stack height may lead to the diminishment of stack-wake Karman vortex shedding. In contrast to conventional JICF, the EJICF configuration exhibits a heightened tendency for recirculation bubble formation in the jet wake region. A spatial mixing analysis demonstrates the capacity of elevated stacks in enhancing the mixing efficiency of transverse jets.