DESIGN, DEVELOPMENT AND PERFORMANCE EVALUATION OF NEW SWIRL EFFERVESCENT INJECTOR

Abstract

The swirl effervescent injector has more desirable characteristics because it allows a system to run on low injection pressure and yet is still able to achieve an efficient atomization. In previous studies on other types of injectors, spray breakup length was reported as one of the important spray characteristics since a shorter spray breakup length tend to provide an earlier atomization. However, intensive studies on spray characteristics of the swirl effervescent injector are scarce. This paper is intended to describe the geometrical design procedures and performance assessments of a newly developed swirl effervescent injector. In designing the injector, a similitude technique was deployed to find the best design attributes among 4 existing injectors. The desired attributes were incorporated into the development of the injector. The swirl chamber was made from Perspex to permit visualization of the internal flow. A test rig was built to evaluate the injector’s performance. Water was used as the working fluid and nitrogen gas as the atomizing agent. The spray breakup characteristics were observed at different GLR and recorded using high-speed shadowgraph technique. For the analyses of the video recordings and the conversion into image sequences, ImageJ and specific software have been deployed. It was found that the introduction of the swirl-generating vane prior to the discharge orifice has assisted in shortening the spray breakup length at any amount of GLR.