Intake and Exhaust Ports Design for Tumble and Mass Flow Rate Improvements in Gasoline Engine 2019-01-0763

In recent years, world-wide automotive manufacturers have been continuously working in the research of suitable technical solutions to meet upcoming stringent carbon dioxide (CO2) emission targets, as defined by international regulatory authorities. Many technologies have been already developed, or are currently under study, to meet legislated targets.

In-line with above objective, the enhancement of turbulence intensity inside the combustion chamber has a significant importance which contributes to accelerating the burning rate, to increase the thermal efficiency and to reduce the cyclic variability [9]. Turbulence generation is mainly achieved during the intake stroke which is strictly affected by the intake port geometry, orientation and to certain extends by combustion chamber masking. Conservation of turbulence intensity till 700~720 crank angle (CA) is achieved by optimized shape of combustion chamber geometry and piston bowl shape. High exhaust port flow also contributes to overall engine efficiency by reduction of residual gas fraction (RGF); this enables high compression ratio (CR) operation by reducing in compression end temperature (CET).

In this work, different geometries of the intake port have been designed and analyzed by means of three dimensional (3D) computational fluid dynamics (CFD) simulations, to foresee the in-cylinder tumble motion development during intake stroke. Final design is manufactured and tested on flow bench. 45% tumble improvement has been attained over base design without loss of mass flow rate (MFR). Similarly exhaust port has also been re-designed by performing numbers of iterations to enhance exhaust port flow and velocity by steady state CFD iterations. Similar to intake port, actual flow measurement is also performed on exhaust port and 36% increase in MFR performance is gained.