Evaluation of multi-hole diesel injectors spray under evaporating conditions: Effects of adjacent spray plumes on the macroscopic and mixture characteristics of target spray

Abstract

Previously, diesel sprays of multi-hole injectors were simulated in an environment where only a single spray plume was simulated. Although boundaries were declared as symmetry, the impact of aerodynamic forces between spray plumes was always neglected. In the present work, all spray plumes of diesel injectors are simulated in a cylindrical box mesh considering external effects including umbrella angle, space between nozzle holes, and hole length to hole diameter ratio. To examine the nozzle hole size effect, two 10-hole diesel injectors with hole diameters of 0.101 and 0.133 mm are investigated under 120 MPa injection pressure. Likewise, to understand the effect of injection pressure, the 0.101 mm hole diameter injector is studied under 120 and 140 MPa rail pressures. In experiments, Laser Absorption Scattering diagnostic technique is applied to visualize the vapor phase, measure mixture concentration and characterize air entrainment. Since Diesel fuel does not absorb UV light, Tracer fuel with the composition of 97.5% of n-tridecane and 2.5% α-Methylnaphthalene is used. On the contrary, sprays are simulated in the Eulerian-Lagrangian two-phase fluid framework using KHRT Breakup and Multicomponent Evaporation models. Parameters such as injection rate and initial spray trajectory angle are measured experimentally and used as input for the spray simulation. Computational results correspond with experiments particularly in terms of Penetration and Equivalence Ratio while Spray Angle deviates.