Study of In-Cylinder Tumble Effect on Spark Ignition Direct Injection (SI-DI) Engine Performance Using Gasoline, CNG & E85 Fuels and Simulation Technique

Vehicles with direct injection engines employ various methods for mixing fuel and air in an engine cylinder. Efficient mixing increases combustion burn rate, improving combustion stability and knock suppression. Spark ignition engines may use tumble flow motion to generate turbulence, which includes rotational motion generally perpendicular to the cylinder axis to improve air and fuel mixing. Depending on operating conditions, more or less tumble may be advantageous. In this paper the tumble motion of the charge air is studied and simulated only in the suction stroke. A direct injected turbocharged combustion system employing central-mounted multihole injector. This paper presents the comparative study of effect of intake port design with various levels of tumble motion for fuels used in SIDI engines on the engine performance characteristics. A high tumble intake port design enforces a well-organized stable motion that results in higher turbulence intensity in the cylinder that in turn leads to faster burn rates, a more stable combustion and less fuel enrichment requirement at full load. A current GDI engine intake port was studied, simulated using 3D simulation workbench for tumble flow and validated on test rig. Based on this, the intake port was modified for optimized tumble ratio for other fuels (gaseous and liquid less volatile) using simulation techniques and the engine performance was evaluated in terms of torque, power and BSFC using 1D engine simulation tool.