Enhancement of Atomization of High Viscous Liquid Jet by Pressure Atomized Type Nozzle

Abstract

The purpose of this study is to develop the atomization enhancement nozzle, which is able to atomize high-viscous liquid jet under low injection pressure from resources saving view point. In this paper, we investigated the effects of kinematic viscosity of the injection liquid and geometric shapes of nozzle on atomization of the spray and spray characteristics of high-viscous liquid. Kinematic viscosity was varied from 0.66x10-6 m 2 /s (0.66 cSt) deserved kerosene and water to 20x10-6 m 2 /s (20 cSt) deserved heavy oil at liquid temperature of 303 K. The break up length and Sauter mean diameter of high-viscous liquid spray were measured in variation of the injection pressure up to 15 MPa (150 bar). The results show that the spray, which spread of the spray is large, the breakup length is short and Sauter mean diameter is small, was obtained, and enhancement of atomization of high-viscous liquid jet is possible under low injection pressure, using a pressure atomized nozzle. Moreover, almost the same spray characteristics were obtained independent of kinematic viscosity, using a nozzle improved a single hole nozzle. Introduction The recycling and effective use of waste materials are regarded as very important from resources saving view point. Moreover, if excellent spray characteristics were obtained at small energy independent of the fuel property, it is possible to have a wide range of application of the fuel. The purpose of this study is to develop the atomization enhancement nozzle, which is able to atomize high-viscous liquid jet under low injection pressure. This paper presents effective atomization of high-viscous liquid. In general, a twin fluid atomizer was used for atomization of high-viscous liquid [1]-[2]. However, the pressure atomized nozzle was used in this study from an energy saving view point and the application of this nozzle to a nozzle for direct injection diesel engine. The pressure atomized nozzle is necessary large energy i.e. high injection pressure in order to obtain excellent spray characteristics, and it is difficult to atomize high-viscous liquid. Atomization of the liquid jet is affected by occurrence of cavitation in the nozzle hole [3]-[13], geometric shapes of nozzle, the injection pressure and the ambient pressure [14]. Especially, the disturbance of the liquid flow in the nozzle hole due to occurrence of cavitation has a dominant effect on atomization of the liquid jet. The atomization enhancement nozzle, which cavitation occurs at relatively low injection pressure and excellent spray characteristics was obtained, was developed, and it was investigated about the application of high-viscous liquid to effective atomization.