The Interaction of Spinning Liquid Film With Swirling Gas in Cylindrical Vessel—Experiments and Numerical Simulations

Experimental flow visualizations and numerical simulations of the interaction of a spinning liquid film with a swirling gas in a cylindrical vessel are reported. A gas/liquid flow that simulates the high-pressure conditions of combustion was successfully visualized in a transparent test chamber. The test chamber was a mockup of a liquid propellant gun ignition system component called the hydrodynamically-stabilized combustor. Water-glycerol mixtures were used for the liquid, and ballistically compressed helium-nitrogen was used for the gas. The liquid is injected tangentially along the cylindrical test chamber wall where it spreads as a spinning film. The gas is then injected tangentially and interacts with the liquid. The flows were insensitive to the tilt angle of the test chamber and only mildly sensitive to the liquid viscosity. Liquid entrainment by the gas and subsequent atomization occurs promptly (within 2 ms) after the onset of gas injection, and the flow in the test chamber vent passage is a swirling, transonic, two-phase flow. Two types of three-dimensional simulations of the liquid and gas injection into the test chamber were performed using the CRAFT Navier-Stokes code. The first type was of the initial liquid flow only. The second type was of the high-pressure gas injection into the chamber, with the liquid initialized in an annulus around the chamber surface with a swirl velocity. The numerical simulations were successful in capturing the primary characteristics of the flow phenomena observed in the experimental flow visualizations. This included yielding the observed liquid flow patterns before gas injection and capturing the cellular structure observed after gas injection.