Transcritical injections under high pressure conditions

In modern diesel engines and liquid rockets, fuel is injected into an environment of high pressure and high temperature. These environmental conditions are often above the critical pressure and temperature of the injected fuel, whereas the fuel is in a subcritical compressed liquid state prior to injection, making it a transcritical injection. Moreover, the mixture of fuel and environmental gas may have a higher critical point than the respective pure substance, resulting in a subcritical mixture and phase separation effects due to multicomponent mixing. Complex thermodynamic models are required to represent and capture these physical phenomena. 

In this research project, we numerically investigate turbulent mixing and two-phase phenomena in liquid fuel injection. For this purpose, we use an extended version of the flow solver OpenFOAM, containing a thermodynamic model that accounts for real gas thermodynamics and phase transition effects. 

The figure shows a transcritical injection with phase separation due to multicomponent mixing. The two-phase region in the mixing zone is visualized by the rainbow color map.