Numerical investigation of destabilization of supercritical round turbulent jets using large eddy simulation

¹ CERFACS Av. G. Coriolis 42, Toulouse cedex 31057, France
² Université de Toulouse INPT, UPS Institut de Mécanique des Fluides de Toulouse (IMFT) Allée Camille Soula, Toulouse 31400, France

Abstract

In rocket engines, dense oxygen is injected in a high-pressure environment, above its critical pressure. Oxygen temperature varies from a subcritical value at injection to a supercritical (SC) value in the burnt gases. Both the Vulcain 2 engine and Space Shuttle main engine use this injection mode. Thermodynamics, mixing, and transport properties are no longer those of a perfect-gas mixture. The present study uses the Large Eddy Simulation (LES) code AVBP, developed at CERFACS to simulate such jets. Dense fluid flows are modeled by the use of a cubic equation of state, in conjunction with appropriate viscosity and thermal conductivity coefficients. A nitrogen round jet at SC pressure injected in a gaseous reservoir is simulated. Two cases are considered, one experiencing a transcritical (TC) injection (high-density injection), while the other one is injected at SC temperature (low-density injection). Mixing efficiency is studied and the stabilizing effect of the density gradients is identified. Results are in good agreement with available measurements. The funding for this research is provided by Snecma and CNES (Centre National d'Etudes Spatiales).