Mixing Enhancement of Liquid Rocket Engine Injector Flow

摘要

An investigation of the mixing enhancement behavior of N2 shear coaxial jets between two injector geometries is presented. A total of 20 cases with one injector geometry and 15 with the other, corresponding to different momentum flux ratios (J's) at subcritical, nearcritical and supercritical pressures are analyzed and compared. The measurements are extracted from 998 backlit images. Acoustic excitation is used to analyze the response of the system to velocity and pressure perturbations. The frequency of the system varied from 2.90 to 3.11 kHz and the maximum peak-to-peak pressure perturbation as a percentage of the mean chamber pressure was 4%. It was found that changing the geometry of injectors of similar size had a large impact on the behavior of the coaxial jet. The qualitative response of one of the injectors to acoustics at low J's in the subcritical regime was completely different to the other. In contrast, when comparing cases with very similar J's, it was found that the normalized dark core length between these cases remains close regardless of phase angle for the two injectors despite the fact that the relative acoustic excitation intensities for subcritical pressures were up to eight times stronger than near and supercritical chamber pressures for one of the injectors and close to 2 times stronger for the other.