Session: 06-04: Performance Systems Modeling and Design

Paper Number: 164693

164693 - Diesel Combustion Modification to Reduce Piston Thermal Loads: A Numerical Study Using 3-D Sector Mesh CFD 

Abstract: 

Mechanical failure of pistons due to heating is a concern in high-power density internal combustion engines for military and heavy-duty commercial applications.  Injection pressure and nozzle diameter are investigated here as diesel combustion modifiers to reduce thermal loads on a heavy-duty diesel engine piston. A 3-D sector mesh CFD (computational fluid dynamics) model was developed based on a validated single-cylinder model, coupled with the piston finite element model to study the transient interaction between combustion and temperature distribution on the piston surface. A 1/8^th sector of the cylinder was used due to the use of an 8-hole injector. Modern diesel engines do not have perfect axis-symmetry because of the complex geometry. Therefore, the implications of plume-to-plume variations when using a sector mesh are investigated by initializing the sector mesh several different ways to understand the consequences of the pre-combustion flow field. A box sweep with 900, 1200, 1700 bar injection pressures and 167, 190, 230 µm nozzle holes was performed by holding the combustion phasing constant at the C100 operating condition (i.e., 1625 rpm, 17 bar IMEP). The largest nozzle hole with the lowest injection pressure was predicted to reduce peak piston temperatures by ~50°C compared to the smallest nozzle hole at the highest injection pressure. Fuel droplet sizes and the injection duration played a major role in dictating combustion and heat transfer. The interaction between the piston and the modified combustion plumes induced local temperature differences up to ~100°C with different configurations of injection pressures and nozzle hole sizes. However, efficiency and emissions are generally worse for the cases with reduced piston thermal load through combustion modification. (OPSEC #9478)

Presenting Author: Avinash Ravikumar Clemson University

Presenting Author Biography: PhD candidate in the department of automotive engineering, Clemson University. The research is focused on using numerical techniques to investigate IC engine wall heat transfer predictions for combustion and cooling.

Authors:

Avinash Ravikumar Clemson University
Brian Gainey Clemson University
Vamshi Korivi Ground Vehicle Systems Centre
Eric Gingrich Ground Vehicle Systems Centre
Michael Tess Ground Vehicle Systems Centre
Joshua Piehl Ground Vehicle Systems Centre
Benjamin Lawler Clemson University