On the ignition and the combustion of supercritical fuel jet-in-cross-flow

Ignition and combustion of fuel in combustion chambers is largely dependent on the dispersion and the mixing of the injected fuel with the ambient air. Most of the present combustion devices operate at elevated pressures and under these conditions, unlike the classical liquid atomization observed at sub-critical pressures, the fuel is dispersed by diffusion-dominated mixing. Investigation of this regime of fuel dispersion and the ensuing combustion requires accurate modeling of the supercritical flow and is very challenging. In this paper, we study the dispersion and the combustion of a supercritical n-decane Jet-in-Cross-Flow (JICF) using high fidelity Large Eddy Simulations (LES). The flow properties are modeled using real-fluid thermodynamics and transport properties. Grid resolution requirements are satisfied without compromising the modeling accuracy with the aid of routines accelerated for Graphics Processing Unit (GPU) computation. Both non-reactive and reactive JICF are considered, and the mixing/combustion zone formed in each case is analyzed. As a result of heat release, the flow in cases with reactive JICF is dominated by relatively large scale structures and the combustion zone is localized in the leeward direction of the jet. A maximum temperature of 2700 K corresponding to a mixture fraction of nearly 0.06 is observed in the reaction zones. The reaction rate and index of the flame are in good agreement with the flame structure and the location of the reaction zone. Further, most of the combustion is located in the region dominated by high degree of fuel-air mixing.