Experimental Study of Spray Merge in Dual Pressure- Swirl Coaxial Injectors

The purpose of this paper is to present experimental data for merging two outlet fluid skirts in a dual pressure- swirl coaxial injector. In this study, a dual pressure- swirl external mixing injector was designed and fabricated. Operational characteristics including discharge coefficient and breakup length were expressed in terms of different injection pressures for internal and external injectors. Utilizing fast shooting, based on the backlighting method, the interaction between of two outlet skirts were investigated and the merge performance map was extracted. The merge performance map results indicated, when the pressure difference of the external injector increases from 0.3 bar to 0.95 bar, the pressure difference of the internal injector for the merge to occur increases. The reason for this increase in this range of external injector injection pressure differences is that, the effect of the internal injector injection pressure for merge in this area is greater than the external injector injection pressure, the external injector skirt is pulled toward the internal injector skirt. For injection pressures difference of more than 0.95 bar in the external injector, because the effect of the external injector injection pressure for merge is greater than the internal injector injection pressure, the internal injector injection pressure difference is reduced for the merge to occur and the internal injector skirt is pulled toward the external injector skirt.