Characteristics of Gas-Centered Swirl-Coaxial Injector with Liquid Flow Excitation

Abstract

Gas-centered swirl-coaxial injectors are typically adopted for staged combustion-cycle engines. The dynamic characteristics of gas-centered swirl-coaxial injectors were investigated in this study by inducing excitation on liquid flow through a mechanical pulsator. The effect of excitation was expressed as the injector transfer function, which was defined by the ratio of manifold pressure to film thickness. The geometry effect was investigated by changing the tangential inlet diameter and gap thickness. As the tangential inlet diameter increased, the excitation effect was significant in the film thickness and spray pattern. When the gap thickness decreased, the gain increased and the frequency at the gain decrease became higher. In addition, the momentum flux ratio was used to confirm the gas flow effect. The gain increased with the momentum flux ratio; however, shear instability resonance did not occur.