The effect of nozzle structure and initial state on the primary breakup of diesel spray

摘要

The quality of atomization dominates the efficiency of combustion and the number of emissions. The primary breakup and nozzle internal flow with a single bubble under different location are studied by employing RNG k-epsilon and VOF models with experimental validation. The effects of nozzle structure (cylinder nozzle and conical nozzle), namely the convergence, are also investigated. The formation of C-shaped fuel dividing the bubble into three parts is analyzed. It is found that the thickness of the fuel film affects the formation of mushroom-shaped spray head due to the energy stored in the compressed bubble. The energy releases a lot when the bubble is far from the nozzle outlet and the energy is the lowest when the bubble is close to the nozzle outlet without enough compression. The second peak of the bubble area is lower when the bubble is far from the outlet inside the conical nozzle due to the acceleration effect. However, the second peak of the bubble area is higher when the bubble is at the middle location in the conical nozzle due to the compression from the environment gas. There is almost no difference between these two nozzles when the bubble is close to the outlet.