Supercritical and Transcritical Real-Fluid Mixing in Diesel Engine Applications.

摘要

A numerical framework for simulating the mixing of supercritical and transcritical fluids with large density ratios is presented. The accurate and robust modeling of real-fluid effects on the fuel/air mixing process is critical in characterizing engine combustion. To describe this mixing process, the double-flux model is extended to systems with real-fluid state equations. For this, an effective specific heat ratio is introduced to eliminate the spurious pressure oscillations that are caused by the nonlinearity of the real-fluid equation of state. High-order WENO spatial discretization scheme is used for the real-fluid flow calculations to account for the large density gradients associated with these flows. One-dimensional single and multicomponent advection test cases and two-dimensional supercritical nitrogen jet mixing and transcritical n-dodecane injection test cases are conducted to show the capability of the present study in application to real-fluid supercritical and transcritical flows. Energy conservation errors, generated due to the double-flux formulation, are acceptable.