Jp-8 Surrogates For Diesel Engine Application: Development, Validation, And Cfd Simulation

摘要

Recently, diesel engine cycle simulation has been acknowledged as an effective way for the development and performance optimization of compression ignition engines operating on a variety of fuels. The goal of this research was, therefore, to develop a JP-8 surrogate with a limited number of fuel components so that its chemical mechanism could be developed for its use with computational fluid dynamics (CFD) codes for enabling time-efficient diesel engine cycle simulation. In order to achieve this goal, a new approach was developed for the formulation of surrogate for compression ignition engine application. The development approach required the surrogate to match several properties of the target JP-8 fuel.A total of six different surrogates, with maximum number of components limited to four, was developed using a MATLAB code, Ignition Quality Tester (IQT), and HYSYS simulation software. Then, all the surrogates were tested in the IQT at different charge air temperatures, and the results of the tests were compared with those for the target JP-8. The surrogate that best reproduced the auto-ignition and combustion characteristics of the target JP-8 in the IQT was then selected for its validation in a single cylinder direct injection research diesel engine operating at different conditions. The similarities between the auto-ignition, combustion, and emissions characteristics of the surrogate and the target JP-8 were then examined to underscore the validity of the surrogate development approach as well as the use of the IQT for surrogate development and preliminary validation. Finally, a reduced chemical mechanism of the surrogate was developed for its use with the CFD codes for diesel engine cycle simulation.The IQT tests showed that the two-component surrogate S2 best reproduced the autoignition and combustion characteristics of the target JP-8. The results of the engine validation tests indicated that the surrogate S2 closely reproduced the autoignition, combustion, and emissions characteristics (Carbon Monoxide, unburned hydrocarbons, and oxides of Nitrogen) of the target JP-8 at the tested conditions. However, the particulate matter concentrations were lower for the surrogate than for the target JP-8. Further, the results of the 3D CFD simulation, which utilized the reduced chemical mechanism of the surrogate S2, were in fairly good agreement with the autoignition, combustion, and emissions data of the surrogate S2 obtained from engine experiments.