Numerical Simulation of Two-Phase Flow Within Aerated-Liquid Injectors

Aerated-liquid atomization involves the injection of a small amount of gas into a liquid stream to initiate primary breakup within the injector itself. The sprays that result have good penetration and lateral dispersion characteristics, and are suitable for fueling high-speed air-breathing propulsion systems. In this study, the flow within aerated-liquid injectors featuring both inside-out and outside-in aeration schemes is simulated using an implicit large-eddy simulation method equipped with a sharp phase-interface-capturing technique and a continuum model for surface tension. Results are compared with time-averaged and time-resolved X-ray measurements of liquid-phase density and imaging obtained at the 7-BM beamline at Argonne National Laboratory using beryllium injector models. A good agreement between computational predictions and experimental measurements is generally achieved, with each indicating that the end state of the aeration process for both injector designs is the formation of a core-annular two-phase flow in the nozzle portion of the injectors. The numerical model is less successful in predicting the structure of the separated two-phase flows observed before the expansion of the mixture through the nozzle. One-dimensionalized liquid-phase density, velocity, and momentum flux distributions obtained from the numerical model and the experiment display a close agreement for all injector configurations.