이중 공기공급 이유체 선회노즐의 유량비 변화에 따른 미립화 특성에 관한 실험적 연구

The regulations to reduce the exhaust emissions from vehicles are becoming increasingly stringent and encompassing more types of vehicles. In the case of heavy duty diesel engines, the Urea-SCR system is currently considered to reduce the NOx emission as a proved technology, and it is widely studied to get the high performance and durability. In the Urea-SCR system, urea-water solution is injected into the exhaust pipe using the specially designed nozzle with high precision dosing unit. However, the injection nozzles occur some problems, including nozzle clogging, deposition of urea-water solution on the inner wall of exhaust pipe. In this study, the atomization characteristics of the dual air supplying twin-fluid swirl nozzle were investigated experimentally using PIV and PDA systems. The effect of assist air flowrate supplying from the dual air port was investigated. The mean velocity, turbulent intensity and SMD distributions of the sprays were measured along the centerline and radial direction. As the experimental results, the higher axial velocity is observed in the central part of the spray, and the SMD decreased with the increase of ALR.