Fluid dynamic efficiency of a high performance multi-valve internal combustion engine during the intake phase

The purpose of the present work is the analysis of the fluid dynamic behaviour of a high performance internal combustion engine during the intake phase. In particular, a four-valve spark-ignition engine has been characterised at the steady flow rig. Dimensionless discharge coefficients have been used to define the global fluid dynamic efficiency of the intake system, while the laser-Doppler anemometry technique has been employed to evaluate the mean flow in the valve curtain area and to characterise the interference phenomena between the two intake valves. The investigation has shown the significant influence of the valve lift on the volumetric efficiency of the intake apparatus. Moreover, the experimental analysis has highlighted that the valve-valve interference phenomena have a relevant impact on the head breathability, on the flow development within the combustion chamber and on the velocity standard deviations.