Combustion Modeling of Split Injection in HSDI Diesel Engines

Abstract

The second-injection ignition delay of HSDI diesel engines is generally shorter than that of the first injection. C. Hasse and N. Peters (2005) estimated the ignition delay of the second injection using 2-dimensional flamelet equations. However, simulation of 2-dimensional flamelet equations requires enormous computational time. Thus, to analyze the combustion phenomena of the split injection mode in HSDI diesel engines effectively, the 2-dimensional flamelet combustion model was modified. To reduce the calculation time, 2-dimensional flamelet equations were only applied near the stoichiometric region. If this region was ignited, the species and temperatures of other regions were changed to the steady-state solutions of 1-dimensional flamelet equations. Using this method, the calculation time for solving flamelet equations was reduced by 80% without any loss of calculation accuracy. The simulation results of the second-injection ignition delay were well matched with the experimental results in a precombusted vessel.

Keywords:

• Constant volume vessel
• Ignition delay time
• Modified two-dimensional flamelet model
• Split injection