Computational Study of Fluidic-Valve Injectors for Detonation Engines

Abstract

The performance of detonation engines depends on propellant injectors. This study investigates a fluidic-valve injector mounted to a detonation tube. The injector is equipped with a recessed cavity connecting to the fuel plenum. After verifying the theoretical and numerical framework, three cases (I, II, and III) are analyzed, each representing different combinations of initial injector conditions and fuel supply setups. In all cases, a detonation wave is initiated near the headend of the detonation tube. It propagates through the initial section of the tube and undergoes diffraction and deformation at the flush-wall orifice. Among the considered cases, Case III, featuring a pre-pressurized initial injector flowfield and a total-pressure-inlet boundary, demonstrates the best agreement with the experimental results. It reveals a strong interaction between the longitudinally traveling detonation wave and the transverse propellant plume expanding from the orifice, causing the detonation wave to split. One part continues within the tube, while the other diffracts into the injector, creating a recirculation zone. Shock waves propagate within the injector and reflect at the base of the cavity, generating pressure spikes similar to the experimental observations. However, the contact surface separating the burnt products and fresh propellant reaches only a limited distance into the injector, suggesting a short interruption time and rapid recovery of the propellant supply.