To Determine the Effect of Dimpled Poppet Valve on the Flow in Engine Cylinder by Port Flow Simulation

Mechanical Engineering Department, Delhi Technological University, Delhi 42, India

Abstract

Intake system is one of the crucial sub-systems in engine, the geometrical configuration of the inlet ports and the valves and their opening schedule creates organized motions in the cylinder, known as swirl (about the cylinder axis) and tumble (orthogonal to the cylinder axis) which help in proper mixing of fuel and air. Surface texturing of intake valve can improve the performance of engine drastically by generating more swirl, turbulent kinetic energy and reducing the coefficient of skin friction in the valve proximity area. Making dimples on intake valve is one of the many ways in which surface texturing can be done and its effectiveness can be easily measured by conducting a steady-state port flow simulation on ANSYS IC fluent solver using standard k-omega model. Port flow analysis was carried on dimpled intake valve at a lift of 5mm for 5 dimple ratio ranging from 0.1 to 0.3 in steps of 0.05. The dimple depth-over diameter ratio is a very crucial parameter in determining the optimum geometry of dimple on which best results are obtained. The results showed that the maximum mass flow rate is obtained at dimple ratio of 0.2 with an increase of 0.005% over the simple intake valve and a 38.4% decrease in the area weighted average skin friction coefficient in valve proximity area was seen in case of dimpled valve.