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The flow and mixing of fluid induced into the cylinder through each of the two intake ports of the spark ignition engine has been studied during intake and compression strokes on horizontal and vertical sections of the engine cylinder by experiment and numerical analysis. In the experiment in order to observe the flow and mixing process of fluid from each port, particles were alternately mixed with air flowing through each of the two intake pipes. And velocity vectors on the sections were measured by means of particle tracking velocimetry. The finite volume method was used in numerical analysis. Flow behavior and mixing of the fluid induced through each intake port were demonstrated in various crank angles and on various sections of cylinder during intake and compression strokes. Comparison between the experimental and numerical results were also made.

To obtain a more reasonable model of torch combustion in a spark ignition engine with a vertical or horizontal prechamber, the instantaneous temperatures of combustion gas are measured by an infrared absorption-emission pyrometer with a narrow band pass filter for CO2 gas, while changing the torch nozzle area and air-fuel ratio. The gas temperature diagrams indicate that the ignition timing, flame propagation and combustion duration in the main chamber with vertical prechamber differ entirely from those with horizontal one. The fact is verified by comparing them with the heat release rates obtained from the pressure diagrams and with the flame propagation taken by means of high-speed photography. The measured gas temperature diagrams are, therefore, found to provide a lot of useful and local information concerning the combustion process and the engine performance in the prechamber engines.