Spray characteristics of gel fuel in a gas-centered coaxial swirl injector with variable recess ratios

This paper has studied the spray characteristics of gel in a series of different gas-centered coaxial injectors by experimental observations. Impacts of recess ratio on breakup features, such as the breakup length, spray angle and droplet size distribution, have been also investigated. The gel spray morphology shows that the spray field could be divided into not-fully and fully-atomization zones with the different gaseous flow rates. Then a critical airflow velocity has been proposed to distinguish the different atomization patterns. Experimental results reveal that the larger recess ratio would widen the droplet spatial distribution, increase the spray angle and reduce the Sauter Mean Diameter (SMD) in the spray field. Besides, the contraction impact of inner gaseous flow could also be visualized by these experiments. It could be an effective way to improve its atomization performance of gel solutions based on the present coaxial injectors.