Modeling Atomization and Break Up in High-Pressure Diesel Sprays

Computation of high pressure Diesel injection requires improvement of present spray atomization and droplet breakup models. The surface wave instability atomization (Wave) model of Reitz [2] has been coupled to a new breakup model (FIPA) which is based on the experimental correlations of Pilch et al.[3]. It has been integrated in the 3D KMB code [1] derived from the Kiva 2 code [4] of Los Alamos already including a stochastic Lagrangian description of sprays. The droplet breakup FIPA model was first fitted and validated using the monodisperse drop breakup experiments of Liu and Reitz [5]. The response of the modified spray model including the global Wave-FIPA breakup model is compared to well characterized data obtained in a high pressure and temperature vessel. This vessel is fitted with a common-rail injection system with a single hole injector tip. Conditions simulating a direct injection diesel engine are obtained (ρ_g = 25kg/m³, P_g = 3 MPa and 6.1 MPa, T_g = 400K and 800K, P_inj from 40 to 150 MPa). Liquid and vapor penetrations in the vessel are well reproduced, even for high injection pressure cases and with or without evaporation.