NUMERICAL SIMULATION OF SPLIT INJECTION USING 105 SPECIES BASED N-DODECANE CHEMICAL KINETIC FLAMELET MODEL FOR DIRECT INJECTION CI ENGINE
Results from numerical simulations involving non-premixed combustion modeling based on flamelet models developed from a reduced 105 species n-dodecane chemical kinetic mechanism  is presented here. This study is primarily aimed to understand the effect of split injection on NOx and soot formation during in-cylinder combustion. The study is divided into two parts: (a) validation of computational setup and (b) parametric studies of effect of split injection in in-cylinder combustion dynamics and emissions.
Validation was performed using reacting and non-reacting spray and combustion data available on Engine Combustion Network (ECN) , a consortium of internationally renowned national laboratories and universities involved in IC engine and combustion studies. "Spray-A" data was used to validate the spray and combustion numerical setup. The validation was performed in a 50×50×100 mm3 constant volume flow domain. Standard k-ε turbulence model and KHRT droplet breakup model were used for spray modelling. Liquid and vapor penetration lengths were used to validation the spray setup and flame lift-off length and ignition delay was used to validate the combustion model setup. The pressure trace from numerical simulation are found to be within a reasonable error limit of 4%. The ignition delay prediction were quite accurate in simulation work. The overall equivalence ratio was maintained the same. In split injection, a small portion of the fuel was injected before the main injection. NOx production will be modelled using Zeldovich mechanism. Only the closed part of the engine cycle will be modelled and the boundary condition was established using motored P-θ curve derived from in-house experiments.