Lagrangian Modeling of Evaporating Sprays at Diesel Engine Conditions: Effects of Multi-Hole Injector Nozzles With JP-8 Surrogates

Report No. ARL-RP-486
Authors: L. Bravo; M. Kurman; C. Kweon; S. Wijeyakulasuriya; P. K. Senecal
Date/Pages: June 2014; 22 pages
Abstract: Numerical modeling of the evaporation process in sprays under diesel conditions is key for the development of efficient injection strategies and to increase combustion efficiency. In this study, three-dimensional numerical simulations of single and two-hole injector nozzles under diesel conditions are conducted to study the spray behavior and the effect of multi-hole nozzles on heavy fueled spray parameters and mixing. The configuration corresponds to a high-pressure JP-8 spray injected into a high temperature pressure vessel (HTPV) flow-through combustion chamber simulating realistic conditions found in diesel engines. A Lagrangian particle tracking method coupled with a classical blob injection wave-based model is adopted through the use of CONVERGE solver to treat the spray process. An Adaptive Mesh Refinement (AMR) and fixed embedding technique is employed to capture the gas-liquid interface with high fidelity while keeping the cell-count reasonable. Two JP-8 liquid fuel surrogates, Surrogate-C (of 60% n-dodecane, 20% methylcyclohexane, 20% o-xylene), and the Modified Aachen surrogate (80% n-dodecane and 20% trimethylbenze) were interrogated resulting in good agreement with high fidelity spray measurements. Spray simulation results are compared to our in-house experimental data for JP-8 with single axial hole and two-hole adjacent (60°) nozzle configurations. Standardized Engine Combustion Network (ECN) Spray A ambient conditions, consisting of 900 K and 60 bar, are selected with a rail pressure of 1000 bar with nominal nozzle diameter dj=147 µm. Utilizing k-∈ Reynolds-Average Navier Stokes, and dynamic structure Large Eddy Simulation methodologies both configurations result in a 20 mm mean liquid length for both single and two hole cases. This is in good agreement with experiments with the single, while for the double hole this is an over-prediction of 3-5 mm. The reported differences are partially attributed to the internal nozzle flow dynamics, reported nozzle eccentricities, the influence of these effects are discussed.
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2014