Large Eddy Simulation of High Reynolds Number Nonreacting and Reacting JP 8 Sprays in a Constant Pressure Flow Vessel With a Detailed Chemistry Approach

Abstract

In military propulsion applications, the characterization of internal combustion engines operating with jet fuel is vital to understand engine performance, combustion phasing, and emissions when JP8 is fully substituted for diesel fuel. In this work, highresolution large eddy simulation (LES) simulations have been performed inorder to provide a comprehensive analysis of the detailed mixture formation process in engine sprays for nozzle configurations of interest to the Army. The first phase examines the behavior of a nonreacting evaporating spray, and demonstrates the accuracy in predicting liquid and vapor transient penetration profiles using a multirealization statistical gridconverged approach. The study was conducted using a suite of singleorifice injectors ranging from 40 to 147 خ¼m at a rail pressure of 1000 bar and chamber conditions at 900 K and 60 bar. The next phase models the nonpremixed combustion behavior of reacting sprays and investigates the submodel ability to predict autoignition and liftoff length (LOL) dynamics. The model is constructed using a Kelvin Helmholtz–Rayleigh Taylor (KH–RT) spray atomization framework coupled to an LES approach. The liquid physical properties are defined using a JP8 mixture containing 80% ndecane and 20% trimethylbenzene (TMB), while the gas phase utilizes the Aachen kinetic mechanism (Hummer, et al., 2007, “Experimental and Kinetic Modeling Study of Combustion of JP8, Its Surrogates, and Reference Components in Laminar Non Premixed Flows,â€‌ Proc. Combust. Inst., 31, pp. 393–400 and Honnet, et al., 2009, “A Surrogate Fuel for Kerosene,â€‌ Proc. Combust. Inst., 32, pp. 485–492) and a detailed chemistry combustion approach. The results are in good agreement with the spray combustion measurements from the Army Research Laboratory (ARL), constant pressure flow (CPF) facility, and provide a robust computational framework for further JP8 studies of spray combustion.