Application of CFD in the Design of Reciprocating Engine for Light Commercial Vehicle Applications

In this chapter, a brief discussion on the design aspects of intake pipe and piston bowl of a single cylinder diesel engine that powers a light commercial vehicle is presented. Length and diameter of the intake pipe are optimized to have higher air flow rate using 1D engine performance simulations. On steady-state engine dynamometer, the optimized intake pipe found to be different than that predicted from simulations. A root cause analysis is performed for this anomaly, and it found that defect components and associated testing procedures result in the anomaly. Details of the analysis are presented. Further optimization of intake pipe yielded higher air flow rates by 3–5%. The measured brake-specific fuel consumption (BSFC), engine-out total unburned hydrocarbons and smoke with optimized intake pipe are significantly lower than those obtained with base intake pipe. 3D combustion CFD simulations are performed on two piston bowl designs, base and modified designs. They differ in geometric parameters of the bowl with the identical compression ratio and injection parameters. The fuel distribution, in-cylinder gas temperature and squish flow are analyzed to understand the effect of the geometric shape of the piston bowl on the combustion. On engine dynamometer testing, it was observed that the modified bowl has lower BSFC and smoke by 3.5% and 52%, respectively. The reasons for the superior performance of the modified bowl are discussed.