Numerical Simulation of Flows in an Engine Cylinder : 2nd Report, Flow in a Deep-bowl Combustion Chamber

Abstract

A finite difference method was applied to simulate the transient flows in the combustion chamber in a deep-bowl direct-injection diesel engine. The flow field was treated as an axisymmetric one in which turbulence and its dissipation were taken into account by using an ordinary k-εmodel. Description of the flows was satisfactory and the computed results were used to draw the characteristics of the flow and to assess the effect of some controlling parameters. The obtained results show that the wall friction reduces angular momentum of the swirl considerably. It is also shown that the swirl intensity largely affects secondary flows induced in the vertical plane in the piston cavity; the flow pattern changes from a simple toroidal vortex to a double-vortex flow as the swirl intensity is increased. A discussion is made on the intensity of turbulence and its effect on the flow field at the end of compression.