A VLE-Based Reacting Flow Solver for High-Pressure Transcritical Two-Phase Combustion

Abstract

The requirement of high power outputs and high efficiencies of combustion engines such as rocket engines, diesel engines and gas turbines has resulted in the incremented of the system pressure close to the critical point. This increase in pressure often leads to the fluids becoming either transcritical or supercritical in state. This has led to increased interest in both the multicomponent phase change phenomena as well as their chemical reactions. Most multi-phase research is usually concentrated on either single or two-component system, hence unable to study the multicomponent phase change and reactions occurring in real engines. This work employs our previously developed thermodynamic model based on vapor-liquid equilibrium (VLE) theory, which predicts the phase separation near mixture critical points, and has been accelerated using in-situ adaptive tabulation (ISAT) for multi-component mixtures and couples this with a simplified reaction mechanism for ECN Spray A like environments. Simulations are conducted using our new VLE-based reacting flow solver to study the effects of phase change on transcritical combustion. An unsteady two-phase mixing layer with thermophysical condition as the ECN-A spray is chosen specifically to study the phase change and combustion phenomena in the transcritical fuel mixture. Results show the reduction in two phase region between the two streams while very good match in ignition delay times showcasing the importance of both transcritical phase change occurring across the mixing layer and turbulent two phase mixing layer development.