Simulation of supercritical fuel injection with condensation

Abstract

Abstract Supercritical injection and the accompanying potential condensation processes were numerically investigated with a consistent treatment for both the fluid dynamics and thermodynamics with a realistic equation of state model. Qualitative and quantitative improvement was seen on the predicted injectant density with real gas simulations when compared to available experimental data, emphasizing the importance of thermodynamic property non-ideality at supercritical conditions. Recently developed phase stability and equilibrium solvers utilizing fundamental thermodynamics principles were also applied to capture phase transitions. To our knowledge, this is the first comprehensive simulation against experimental data of supercritical injection with phase separation. Furthermore, the simulation results were found to agree with the experimental results in three aspects related to the phase change. The first observation is that condensation is predicted to occur if and only if the temperature difference between the injectant and ambient is large enough to promote strong heat transfer interactions. The simulations also show that condensation becomes intensified when the chamber temperature is further reduced. Second, such condensation is only possible for supercritical-to-subcritical but not for supercritical-to-supercritical injections. Third, a condensed liquid phase is found to form at the jet boundary where the energy and mixing interactions between the “hot” injectant and the “cold” surrounding gas are strong. The intensive local heat exchange finally sends the mixture into the two-phase region by crossing the dew point line with condensation.