Investigation of Confinement and Heat Release Effects on Fluid Dynamics in a Scramjet Using IDDES

摘要

This paper presents a numerical investigation of the fluid dynamics in a scramjet using the Improved Delayed Detached Eddy Simulation (IDDES). IDDES is a hybrid LES/RANS method implementing LES in the detached flow regions and RANS near the walls. In order to investigate the impact of confinement and heat release on the fluid dynamics, three configurations are studied: a non-reacting case without confinement, a non-reacting case in a model scramjet, and a reacting case in a model scramjet. The reacting and non reacting cases were validated using available experimental data. The mixing process is outlined by the development of the mixing region. The flow in the mixing region in characterized by analyzing the velocity gradient tensor, addressing the fluid deformation and rotation in different regions. Further analysis is presented by looking at the different source terms in the vorticity transport equation. Results show that the dominant mechanism of vorticity transport varies along the spatially-developing mixing region. Vortex stretching dominates the fluid dynamics in the recirculation zone, whereas vorticity generation by compression and baroclinic torque dominate the mixing layer downstream. It is notable that the impact of baroclinic torque on vorticity transport is slightly amplified by the shock train in the non-reacting cases, and is significantly enhanced due to heat release.