Vortex simulation of the intake flow in a planar piston-chamber device

Abstract

A numerical scheme based on the application of the vortex method to update the vorticity field and the implementation of the finite element method to satisfy the normal velocity boundary condition inside a complex time-dependent geometry is applied to simulate the flow produced by a piston sliding out of a chamber equipped with single or multiple intakes. This unsteady confined vortex flow is of interest in many applications. We use the idealization that the flow is incompressible, two-dimensional and planar and we analyse the results to study the flow during the intake process inside a model of an engine cylinder. The chamber top is fitted with an inlet channel, an inlet port or an inlet valve. In all cases when the intake channel axis coincides with that of the chamber, the flow in each side of the chamber consists essentially of two large counter-rotating eddies of almost the same size. The computed structures of these flows resemble qualitatively those which have been observed experimentally. The fluid motion is also computed for the case of a chamber equipped with an intake whose axis is not aligned with the chamber axis. In this case the flow at the end of the stroke is dominated by a single large eddy produced by the merging of the two eddies forming on the sides of the port.