ABSTRACT
The basic processes of spark-ignition engines include mixture formation, ignition, combustion, and combustion products formation. A spark-ignition engine converts chemical energy into heat and then mechanical energy by combustion. High octane number fuels are used in spark-ignition engines. The fuel is inducted to an engine's cylinder in four ways: carburetor, manifold injection, port injection, and direct injection. Volumetric air efficiency is defined as the ratio of actual mass flow rate of air to the theoretical air flow rate. The life of a spark is categorized into three phases: breakdown phase, arc phase, and glow phase. Heat release rate indicates how much quantity of chemical energy is converted into heat per degree crank angle. The laminar speed can be defined as the velocity at which a flame propagates into a premixed unburned mixture. Spray penetration is a measure of the depth of the spray and it indicates how much distance the spray traces before the fuel droplets are vaporized.
