A flamelet/progress-variable approach for the simulation of turbulent combustion of real gas mixtures

The industrial and scientific communities are devoting major research efforts to identify and assess critical technologies for new advanced propulsive concepts: combustion at high pressure has been assumed as a key issue to achieve better propulsive performance and lower environmental impact, as long as the replacement of hydrogen with a hydrocarbon, to reduce the costs related to ground operations (propellant handling, infrastructure and procedures) and increase flexibility. For the class of engines of interest in this work, namely liquid-propellant rocket engines, the pressure is always supercritical, whereas the temperature could be either sub- or super-critical; however, propellants are typically injected into an environment that exceeds the critical temperature and pressure for both fuel and oxidizer, therefore a fast transition to a supercritical state is observed. In such a condition, it is possible to neglect the liquid phase and treat the liquid as a "dense" gaseous jet. However, the ideal gas equation of state is not suitable for computing the correct p-v-T relationship for oxygen and fuel at the operating pressure and temperature typical of LOx/HC rocket combustion chambers. Therefore, a suitable equation of state together with adequate model equations for the transport properties are employed. Starting from this background, the current work provides a model for the numerical simulation of high-pressure turbulent combustion employing detailed chemistry description, embedded in a Reynolds averaged Navier-Stokes equations solver with a Low Reynolds number k-ε turbulence model.