Dynamic mesh analysis by numerical simulation of internal combustion engines

Abstract

A continuous increase in levels of atmospheric pollution and emission restrictions has forced scientists and engineers to adopt new strategies to improve and develop internal combustion engines. One strategy is based on the development of new simulation methodologies using computational fluid dynamic (CFD) techniques, proposed in the present article. In this study,the dynamic loop methodology with ANSYS Fluent code is proposed to perform the numerical simulation ofa four-stroke spark ignition engine. The complexity of the real case was first simplified with three-dimensional CAD geometry, which was then discretized in ANSYS Meshing, whereby a hybrid mesh was created using prismatic and tetrahedral elements. Simulations for in-cylinder analyses were performed in cold flow and employing common flow parameters, such as swirl and tumble. The mesh quality results were classified as good or excellent, being higher than 0.79 for orthogonal quality criteria and lower than 0.36 for skewness criteria. Turbulent effects were introduced concerning the opening and closing of the valves. It was found that the turbulence increases during the intake stroke up to 90°, and during the power stroke, wherein the of the piston bowl, had a great contributionthat can be seen from the swirl and tumble profile for the engine cycle. In the case of the turbulence intensity, a sharp increase was registered during the admission step up to 90°, at which point the turbulence intensity was 4.0. It canbe concluded that this is an innovative approach, capable of simulating the engine motion profile in cold flow.

Keywords:
cold flow; dynamic mesh; internal combustion engine; swirl; turbulence intensity