Optical measurements of flame propagation in a spark ignition engine with a horizontal prechamber

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To understand the combustion process in a spark ignition engine with an unscavenged horizontal prechamber, the flame propagations in both the pre- and main chambers are simultaneously visualized with a high-speed camera, while keeping the volumetric efficiency, air-fuel ratio, and engine speed constant. By using a CCD video camera and an A/D converter, the flame photographs are converted to digital image data (512×512 pixels) and image-processed with a personal computer through thresholding and edge-detecting operations.Consequently, the flame front images edge-enhanced are used to make flame front maps, which are able to examine in detail the combustion process. The brightness distributions of burnt gas in the main chamber are also obtained from the flame image data. The averaged brightness diagrams show a reasonable agreement with the gas temperature diagrams measured by an infrared pyrometer.To understand the combustion process in a spark ignition engine with an unscavenged horizontal prechamber, the flame propagations in both the pre- and main chambers are simultaneously visualized with a high-speed camera, while keeping the volumetric efficiency, air-fuel ratio, and engine speed constant. By using a CCD video camera and an A/D converter, the flame photographs are converted to digital image data (512×512 pixels) and image-processed with a personal computer through thresholding and edge-detecting operations.Consequently, the flame front images edge-enhanced are used to make flame front maps, which are able to examine in detail the combustion process. The brightness distributions of burnt gas in the main chamber are also obtained from the flame image data. The averaged brightness diagrams show a reasonable agreement with the gas temperature diagrams measured by an infrared pyrometer.