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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.

Deposit formation in the induction system of port-fuel-injected engines depends on the fuel-droplet/metal-surface interaction. Previous studies have shown that the metal surface temperature is a critical parameter in deposit formation. Droplet-surface behavior is characterized by the droplet boiling temperature, Nukiyama temperature (at which the droplet has a minimum lifetime), and the Leidenfrost temperature (at which the droplet levitates above the surface on a vapor layer and has a maximum lifetime). In this work, we investigate the effect of fuel additives on deposit formation and on the Leidenfrost temperature. Two experimental apparatuses were used. To determine the temperature range of deposit formation for fuels with different additives, droplets were allowed to impinge upon a heated ramp with a large temperature gradient. The temperature at which the droplets stop sliding and disappear was determined from the position of the residue formation on the ramp.