Intake Manifold Shape Influence on the Unsteady In-Cylinder Flow: Application on LPG Bi-fuel Engine

The flow in the internal combustion (IC) engine intake manifold determines the flow in the cylinder prior and during the combustion. Consequently, intake-air manifolds have a major effect on engine’s performances and emission pollutants. In order to achieve the best volumetric and thermal efficiency, the design of intake manifolds presents a very important objective for engines manufacturers. In this paper, the flow characteristics of air-fuel mixture flowing in various designs of manifold of IVECO 6 cylinder heavy-duty engine are studied. This engine operates with bi-fuel LPG (liquefied petroleum gas)-gasoline technology. The proposed paper aims to present a three dimensional unsteady CFD (Computational Fluid Dynamics) analysis of the flow inside the two manifold shapes. The mass flow rate of the in-cylinder charge, the velocity and the turbulent kinetic energy are investigated in order to develop a thorough understanding of the in-cylinder flow and identify the optimal manifold. The cyclic dynamic in-cylinder flow results show that the second intake manifold shape present the optimal configuration for engine charging. The comparison between simulation results and those from the literature showed a good concordance.