ASYMMETRIC BREAKUP OF ANNULAR LIQUID SHEETS IN LIQUID-CENTERED SWIRL COAXIAL INJECTORS

Cryogenic rocket engines use swirl coaxial injectors due to their consistent spray characteristics over a wide range of operating conditions. Axisymmetric liquid sheets are formed in liquid-centred swirl coaxial injectors of cryogenic engines at their nominal operating conditions. The azimuthal uniformity of the spray formed in this type of injector depends on the swirler configuration and geometry of the flow passages. The liquid sheet breaks into ligaments and then into multitude of droplets due to aerodynamic interaction of the liquid sheet with the surrounding gas. The inner and outer swirl injectors are cold flow characterized using water and nitrogen gas, respectively. Asymmetric breakup of conical liquid sheets was investigated at different gas Weber numbers using flow visualization techniques. Azimuthal uniformity of the spray was determined from the measurements of mechanical patternator. It is of paramount importance to determine the effect of gas swirl on spray uniformity of liquid-centered swirl coaxial injector for different gas-to-liquid mass ratios. It was observed that swirl in the co-flowing gas reduces the inherent asymmetry of the liquid sheet.