Pulsation dynamics in a gas-centered swirl coaxial injector
Gas-centered swirl coaxial (GCSC) injectors, in which a gaseous jet fragments an annular swirling liquid sheet, are used in the liquid rocket engines that works on an oxidizer-rich staged combustion cycle. A steady injector operation is desirable in the smooth functioning of the engine. Gas-liquid coaxial injectors invariably involve a shear layer between a fast-moving gas stream and a slow-moving liquid stream. As a result, different breakup regimes are observed in GCSC injectors, where one of the regimes is pulsating at certain momentum flux ratios. Such unsteadiness in the mass flow can be detrimental to the stability characteristics. I will present some results on characterization of such flows, influence of geometrical and liquid properties on the pulsating flow and understanding of the memory effect of the upstream instability as the flow evolves downstream. I will also discuss the response of the pulsating spray to the external forcing of the gas jet. The findings can be instrumental in identifying strategies to suppress the dominant frequency or control it in GCSC injectors, and thereby, avoid thermoacoustic coupling in combustors.
Contact Nathanael Machicoane for more information or to schedule a discussion with the seminar speaker.