Flow Characterization of a High Performance S.I. Engine Intake System. - Part 1: Experimental Analysis

In this work an experimental analysis is performed to evaluate the influence of different flow bench test conditions and system configurations on the flow characteristics in the intake system of a high performance 4-valve, SI Internal Combustion Engine: valve lift, test pressure drop, throttle valve aperture, throttle valve opening direction in respect to the intake system layout (i.e. clockwise/counterclockwise), presence of the tumble adaptor. To this aim, experimental tests are performed on a Ducati Corse racing engine cylinder head, by measuring the discharge coefficient and the tumble coefficient. The several experimental data obtained by combining the different operational and geometrical parameters are analysed and discussed. Since the flow pattern is widely dependent on the tumble condition onset, particular attention is given to the comparison between the dicharge coefficient values obtained in standard flow bench configuration and the ones measured by inserting the tumble adaptor for the tumble coefficient evaluation. A marked dependence of the tumble coefficient on the throttle valve opening direction, evidenced at part load aperture, was also analysed by means of 3D numerical simulations.