Two-stage Lagrangian modeling of ignition processes in ignition quality tester and constant volume combustion chambers
KAUST DepartmentClean Combustion Research Center
Permanent link to this recordhttp://hdl.handle.net/10754/621754
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AbstractThe ignition characteristics of isooctane and n-heptane in an ignition quality tester (IQT) were simulated using a two-stage Lagrangian (TSL) model, which is a zero-dimensional (0-D) reactor network method. The TSL model was also used to simulate the ignition delay of n-dodecane and n-heptane in a constant volume combustion chamber (CVCC), which is archived in the engine combustion network (ECN) library (http://www.ca.sandia.gov/ecn). A detailed chemical kinetic model for gasoline surrogates from the Lawrence Livermore National Laboratory (LLNL) was utilized for the simulation of n-heptane and isooctane. Additional simulations were performed using an optimized gasoline surrogate mechanism from RWTH Aachen University. Validations of the simulated data were also performed with experimental results from an IQT at KAUST. For simulation of n-dodecane in the CVCC, two n-dodecane kinetic models from the literature were utilized. The primary aim of this study is to test the ability of TSL to replicate ignition timings in the IQT and the CVCC. The agreement between the model and the experiment is acceptable except for isooctane in the IQT and n-heptane and n-dodecane in the CVCC. The ability of the simulations to replicate observable trends in ignition delay times with regard to changes in ambient temperature and pressure allows the model to provide insights into the reactions contributing towards ignition. Thus, the TSL model was further employed to investigate the physical and chemical processes responsible for controlling the overall ignition under various conditions. The effects of exothermicity, ambient pressure, and ambient oxygen concentration on first stage ignition were also studied. Increasing ambient pressure and oxygen concentration was found to shorten the overall ignition delay time, but does not affect the timing of the first stage ignition. Additionally, the temperature at the end of the first stage ignition was found to increase at higher ambient pressure and oxygen concentration. Sensitivity analysis was performed using the TSL model to elucidate the reactions that control the overall ignition process. The present TSL modeling approach demonstrates the suitability of using detailed chemical kinetic models to provide insights into spray combustion processes. © 2016 Elsevier Ltd
CitationAlfazazi A, Kuti OA, Naser N, Chung SH, Sarathy SM (2016) Two-stage Lagrangian modeling of ignition processes in ignition quality tester and constant volume combustion chambers. Fuel 185: 589–598. Available: http://dx.doi.org/10.1016/j.fuel.2016.08.017.
SponsorsThis work was performed by the Clean Combustion Research Center with funding from King Abdullah University of Science and Technology (KAUST) and Saudi Aramco under the FUELCOM program. Research reported in this publication was also supported by competitive research funding from KAUST. We thank Samah Y. Mohammed and Nour Atef of Combustion and Pyrolysis Chemistry Team at KAUST for their valuable contributions. We appreciate the assistance of Dr. Lyle M. Pickett from Sandia National Laboratory Combustion Research Facility for guidance in TSL modeling.