0/1 and 3 - dimensional cold flow analysis of a diesel engine: A case study

Abstract

Gas motion in the engine cylinder plays a critical role in the air-fuel mixing and combustion processes in diesel engines. Moreover, it influences the engine's performance and emissions, as well as its heat transfer. The intake air motion regulates the main phases of the flow in the cylinder, which is characterized by swirl, squish, and turbulence. Inducing swirl and tumble in the intake process provides high turbulence levels at ignition, resulting in more effective flame speeds and better combustion for lean air-fuel ratios or with EGR. This high turbulence also allows the flame front to reach the end gas before the chemical reactions start, leading to auto-ignition for usual air-fuel ratios. Additionally, it enables higher compression ratios without engine knocking. Computational fluid dynamics (CFD) software is used to enhance in-cylinder flow characteristics, and in this study, cold flow simulation of a naturally aspirated, direct injection diesel engine was conducted using AVL Fire M. Swirl, tumble, and TKE parameters were investigated to make a detailed analysis of the in-cylinder flow for the relevant engine.