Effects of asymmetric intake valve lift configuration towards in-cylinder air flow behavior

Abstract

Air motion in a cylinder of a spark ignition engine affects the air-fuel mixing behavior, combustion quality and the production of the exhaust gas emission. With upcoming stringent market regulations for petrol engines, it is necessary to enhance air-fuel mixing for proper combustion. Air-fuel mixing in an engine combustion chamber is studied by assessing the induced air flow swirl motion. Swirl is a rotational motion of a bulk mass within cylinder. Swirl is generated by shaping and contouring the intake manifold, valve ports and even the piston face. Swirl enhances air-fuel mixing and helps to spread flame-front during combustion. The objective of this paper is to analyze the impact of the asymmetric intake valve lift configurations towards in-cylinder air flow swirl behavior. The study is done on 4 cylinders, 1.3L engine. The engine has 2 intake valves in every cylinder. Computational Fluid Dynamics (CFD) was used as a tool to assess the swirl motion in the case study models. At the end of this paper, the characteristics of the swirl flow motion on every case study models is studied by measuring the swirl ratio value inside the combustion chamber. Also, the pattern of the swirling flow inside the combustion chamber is studied by analyzing the velocity vector and turbulent kinetic energy plots.