Abstract
Computational fluid dynamic and chemical simulation is used to investigate the ignition and combustion processes in a pior experimental wave rotor combustor that used a stationary pre-combustion chamber to produce a traversing hot reactive jet or torch for rapid ignition in the wave rotor. The traversing jet delivers reactive hot gas into a premixed ethylene-air mixture in a constant volume combustor from a continuous-flow prechamber torch igniter positioned at a fixed location adjacent to one end of the wave rotor with a clearance gap. This finite-volume fluid dynamics and combustion simulation consider three channels of the wave rotor, with combustion simulated fully in one channel, to optimize computational cost while closely mimicking the traversing jet motion and subsequent ignition and combustion processes using a transient Reynolds Averaged Navier-Stokes two-equation eddy-viscosity turbulence model with detailed chemistry mechanism with 81 species and 573 reactions. The simulation begins at a point in the wave rotor cycle when the channel contains an unburnt uniform mixture with substantial and varied residual turbulence. The pressure rise, flame travel, and heat release rates predicted are compared with experimental data previously collected from a highly instrumented wave rotor constant volume combustor rig. Experimental conditions that had not been measured, but which may affect its combustion processes include turbulent kinetic energy and turbulence scales of the mixture prior to ignition, and the level of active radicals in the traversing hot jet. The pre-chamber combustion model is manipulated to understand how dosing of free radical species enhances localized ignition initiation and affects overall fuel burn. The initial turbulent properties were varied to understand the sensitivity of combustion to turbulence as the flame propagates away from the initial ignition jet zone. These findings advance the understanding of a demonstrated wave rotor combustor with potential to revolutionize gas turbine engine technology.
