Flow Characterization of a High Performance S.I. Engine Intake System - Part 2: Numerical Analysis

In this paper a numerical analysis is carried out of the flow characteristics in the intake system of a high performance engine. To this aim, the experimental flow bench results - obtained in tests performed on a Ducati Corse 4 valves racing engine head and presented in the parallel work [1] - are compared with the numerical ones. In [1] an experimental analysis was performed to evaluate the influence, on the flow characteristics in the intake system of a high performance 4 stroke - 4 valve internal combustion engine Notwithstanding the macroscopic meaning of the measured global coefficients Cd (Discharge Coefficient) and Nt (Tumble Number), the comparative analysis of their respective trends allowed some hypotheses to be drawn on the flow development internally to intake system ducts. In order to confirm the conclusions drawn in [1] and to reach a deeper insight in the flow characteristics, numerical simulations were performed. The geometry of the whole intake system, including throttle valve and poppet valves, was implemented and simulations performed by a modified version of the KIVA code. The influence of the grid spacing and of the turbulence model is analyzed. The numerical results permit to carry out a deeper analysis well to understand the complex fluid dynamics processes that occur in the intake system.