Affiliation:
1. Indian Institute of Technology Bombay, Mumbai, Maharashtra 400 076, India
2. Indian Space Research Organisation, Valiamala, Thiruvananthapuram, Kerala 695 547, India
Abstract
The objective of the present work is to examine the effects of the acoustically forced gas jet on self-pulsating sprays generated from a gas-centered swirl coaxial injector. We conduct the experiments on self-pulsating spray by forcing the gas jet over a range of forcing frequencies and amplitudes. Various image processing techniques, including proper orthogonal decomposition (POD), have been employed to characterize the spray response. Our spatial mapping of dominant frequencies from time-resolved spray width reveals that although both natural and forcing frequencies prevail in the primary breakup region, a modulation frequency (corresponding to the double of the beat frequency) outcompetes the others. The spatial influence of the forcing is also evaluated by measuring liquid mass fluctuations and drop size statistics at various downstream locations. The experiments were extended to investigate the role of various geometrical parameters, such as swirl number, recess, and length of the gas line on the spray response. The influence of the forcing was observed to prevail even in the liquid mass shedding zone with the appearance of all dominant frequencies. This may have important consequences on the thermoacoustic stability of the combustor. In any case, far downstream of the nozzle, the influence of acoustic forcing is not significant to alter the droplet statistics.
Funder
Indian Space Research Organisation
Publisher
American Institute of Aeronautics and Astronautics (AIAA)