Formation of Fuel Mixture in a SI Two Stroke Engine with Direct Pneumatic Injection

Paper includes a description of a two-stroke engine with a rich mixture injection system. The injection of the fuel mixture follows from an additional chamber as a result of pressure difference between the chamber and the cylinder. Formation of the fuel mixture both in the chamber and in the cylinder is described by a simple mathematical model. The fuelling system of the engine was analysed both by use of zero-dimensional model and 3-dimensional model on the base of modified KIVA program. The results were compared with that obtained from the simple computer program based on given mathematical equations and experimental tests on real engines. A diagram of the fuelling system explains a principle of work and enclosed figures show variation of pressure and temperature in the chamber, vaporisation of fuel during crankshaft rotation and visualisation of the mixture injection to the cylinder at different engine speeds. The system is designed for one-cylinder two-stroke engine, but can be applied also for multi-cylinder engines. The described system is one of the step in development of two-stroke engines of small power. The paper describes the second stage of work sponsored by Polish Scientific Committee.