Numerical Analysis of Tumble, Cross Tumble and Swirl Ratios in a Single Cylinder Research Engine

Abstract

In-cylinder flow such as tumble and swirl has an important role on the engine combustion efficiencies and emission formations. In particular, the tumble flow whichis dominant in current high performance gasoline engines has an important effect on the fuel consumption and exhaust emissions under part load conditions. In this research a numerical analysis on a single cylinder engine using computational fluid dynamics (CFD) is presented. From the results of the commercial code, the tumble, cross-tumble and swirl ratios are calculated for evaluating the flow development through intake and compression strokes. The reliability of the results is accessed through a validation process, which consists of comparing numerical and experimental results for in-cylinder pressure, along with a grid independence study. The results for the in-cylinder pressure show good agreement between numerical and experimental results, and the grid independence is rapidly achieved. The results for rotational ratios around X and Z axis show lower and unstable values, and indicate that the vortex on those plane change its rotation direction. On the other hand, the ratio around Y axis has the greater values, and also keeps its rotation direction.