Prediction of In-Cylinder Turbulence for IC Engines

Abstract

This paper presents the preliminary results of some of a few of its kind efforts in large eddy simulation (LES) of engine flows to predict turbulent fluctuations, and the statistics of turbulence quantities inside IC engine cylinders. For this purpose, the well-known engine simulation code, KIVA, is used with special precautions to keep the numerical accuracy at a sufficiently high level, as well as using relatively fine grid resolution. The capabilities of this code are tested against benchmark cases, such as lid-driven cavity flow, and swirling and non-swirling free jet flows. It is then applied to a typical engine geometry under motored conditions. In particular, turbulence generated during the intake stroke, and the instabilities induced by a typical piston-bowl assembly are investigated. The computed velocity fluctuations, correlation coefficients and energy spectra of turbulent fluctuations are compared to experimental results. The predictions seem to extend well into the inertial range of turbulence and depict a good qualitative agreement with measurements. The results also shed light into the mechanisms by which turbulence may be generated by the piston-bowl assembly.

Keywords:

• Turbulence
• CFD
• Large Eddy Simulation
• IC-Engines
• KIVA
• Jet Flow