Search Results

Planar laser induced fluorescence (PLIF) imaging of hydroxyl (OH) radicals is applied to a single cylinder spark ignited internal combustion engine (ICE) to study the development of turbulent flames. A single laser pulse from an excimer laser is formed into a two-dimensional (2-D) light sheet which intersects the flame in the combustion chamber at different delay times after the spark ignition, and 1 mm below the spark plug. The PLIF images are then captured with an intensified charge coupled device (CCD) camera, which is time gated with the laser pulse. The single-laser pulse PLIF images are then stored with a video cassette recorder (VCR) for further analysis. Real-time PLIF images were observed at different delay times after the spark ignition from consecutive engine cycles and at different engine speeds running on propane. Cycle-to-cycle variations were observed.

In this investigation, recently developed techniques to locate knock origins were applied to study fuel and deposit effects as they interact with charge motion. Particularly, the individual and interactive effects of swirl, fuel composition, localized heating, and deposits on in-cylinder knock origin were studied. A Waukesha Split Head CFR engine was modified to accept four pressure transducers for calculating by triangulation the cycle resolved in-cylinder origin of engine knock. Location of the origin of knock within the combustion chamber was based on the difference in time for each pressure transducer to register the onset of knock during the combustion cycle. Computer software was developed and optimized to maximize the success rate in locating knock within 1 cm. In order to explore the difference in location of knock due to fluid dynamics within the cylinder, the shrouded intake valve of the engine was modified to create different swirl conditions within the combustion chamber.

High boiling point components of gasoline have been shown to have an adverse effect on engine-out hydrocarbon emissions for port fuel injected (PFI) engines. Fuel charge inhomogeneity and wall wetting contributes to the abnormally high hydrocarbon emissions associated with cold and warm engine starting. In this work, a series of aldehydes with varying molecular weight and boiling points were used as fluorescent tracers to study the effect of fuel volatility and engine operating conditions on the in-cylinder charge distribution. The tests were conducted in an optically accessible engine consisting of a production GM Quad-4 cylinder head and intake manifold, with an FEV systemmotor crankcase and “Bowditch” transparent piston. Planar laser induced fluorescence was used to study the in-cylinder fuel vapor distribution and to determine the presence of liquid droplets.