ID 96

Effect of liquid properties on spray characteristics of gas-centered swirl coaxial injectors under various ambient pressure

 

Abstract:

As a kind of practical injectors widely used in liquid oxygen-kerosene rocket engines, gas-centered swirl co-axial (GCSC) injectors have attracted more and more attention over recent decades. Most of previous experi-ments are dedicated to the effect of geometric parameters and momentum flux ratio on the spray patterns un-der various pressures and room temperature. However, the effect of liquid temperature has not been investigat-ed previously. In this work, spray characteristics, such as intact length and spray cone angle, under various am-bient pressures, liquid temperatures and gas flow rates, are analyzed based on back-illuminated high-speed im-aging technique. Three sheet breakup regimes, namely perforated breakup, wave-assisted breakup and early breakup, are identified under different conditions. The intact length decreases under the order of perforated breakup, wave-assisted breakup and early breakup, while the spray cone angle reaches its minimum under the wave-assisted breakup regime. A retarded transition from perforated breakup to wave-assisted breakup and then to early breakup with increasing central gas flow rate is revealed at elevated liquid temperature and ambi-ent pressure. These results provide insightful information for understanding the breakup mechanism and up-grading the design criteria of GCSC injectors.