Results on Subcritical One-Phase Coaxial Jet Spread Angles and Subcritical to Supercritical Acoustically Forced Coaxial Jet Dark Core Lengths (Preprint); Conference paper

摘要

An investigation of the behavior of N2 gas-gas shear coaxial jet spread angles in conjunction with a comprehensive N2 shear coaxial jet dark core length analysis is presented. For the one-phase coaxial jet spread angle study, a total of 6 cases, corresponding to different momentum flux ratios (MR's) at subcritical pressures are analyzed and compared to existing data. The measurements were extracted from 20 backlit images with the chamber to outer jet density ratio varying from 0.17-4.8. The objective of the second part of this work is to study the effect on the magnitude of the inner jet dark core length of transverse acoustic forcing at subcritical to supercritical pressure environments. The dark core length data comprises MR's from 0.02 to 23 with corresponding velocity ratios from 0.25 to 23. In these acoustically-forced cases, the resonant frequency of the system varied from 2.93 to 3.09 kHz and the maximum root-mean-square pressure variation with respect to total pressure was 4%. When comparing cases with very similar MR's, it was found that the relative acoustic excitation intensities for subcritical pressures were up to eight times stronger than near and supercritical chamber pressures. Despite that fact, the corresponding relative change in length of the dark core did not vary more than 50% between the three pressure regimes.