Tetsunori Suzuoki

Autoignition-delay measurement over lean to rich mixtures of n-butane/air under swirl conditions

Abstract The autoignition delays over lean to rich mixtures of butane/air under various speeds of swirl flow were measured in a rapid compression experiment, together with photographic observation at 3000 frames per second. A lot of interesting features of the autoignition delay and the autoignition process were observed. Especially, it has been found that the swirl preferentially lengthens the autoignition delays of richer mixtures while lean mixtures with equivalence ratios less than about 0.6 are affected only little. With the results of computer simulation, it is concluded that this preferential effect indicates that the adiabatic core, in which the autoignition chemistry proceeds adiabatically, breaks more easily in richer mixtures at higher swirl speeds. Although the detailed mechanism of this preferential breakdown could not be clarified, this and other features of the autoignition under the swirl were fully discussed and interpreted.

Development of instrument for measurement of fuel-air ratio in vicinity of spark plug : application to DI gasoline engine

Abstract An instrument to measure time-resolved fuel–air ratio in the vicinity of a spark plug was developed. Properties of absorption and scattering at the wavelengths of visible and infrared rays were utilized to determine the fuel–air ratio in the mixture including liquid and vaporized fuel. The measurement error of the instrument was within 10% as a result of comparison between the overall and the measured fuel–air ratio at the vicinity of the spark plug under the inlet port injection, which forms a relatively homogeneous mixture. The instrument was applied to a direct injection gasoline engine and the mixture formation process was clarified.

Ammonia as a hydrogen energy carrier and its application to internal combustion engines

Anhydrous liquid ammonia offers a considerable advantage over hydrogen in that it has a large volumetric energy density. The total amount of energy that would be expended for its production and transportation to consumers is estimated to be less than that for liquid hydrogen transportation, even if the lower heating value loss is considered. From a storage viewpoint, these advantages would be particularly beneficial to those vehicles carrying large amounts of freight.

Fundamental analysis on auto-ignition condition of a lubricant oil droplet for understanding a mechanism of low-speed pre-ignition in highly charged spark-ignition engines

This article presents a study of the mechanism that the lubricant oil droplet initiates low-speed pre-ignition in highly boosted downsized gasoline engines. Low-speed pre-ignition is a phenomenon that the fuel–air mixture ignites before the spark timing, leading to flame propagation that results in a heavy knock. The ignition of lubricant oil droplets is thought to be one possible mechanism for low-speed pre-ignition. However, the oil droplet ignition conditions are not yet well understood. First, the conditions under which a single oil droplet initiates the combustion of a fuel–air mixture were investigated using a rapid compression and expansion machine. When an initial droplet temperature was above 250 °C, the vaporized oil ignited before the gasoline–air mixture, in which case the combustion of the gasoline–air mixture around the droplet was initiated. The numerical results showed that the oil droplet temperature increases above 250 °C if the droplet is heated by burned gas remaining in the combustion chamber from the previous cycle. A direct-injection single-cylinder research engine was operated under the condition that no residual gas exists in the combustion chamber. In this case, no low-speed pre-ignition occurred even if gross indicated that mean effective pressure was 2.5 MPa. These results indicate that an oil droplet does not cause low-speed pre-ignition if any droplet flies into the combustion chamber unless it remains in the chamber over the exhaust stroke.

Development of Instrument for Measurement of Fuel-Air Ratio in the Vicinity of Spark Plug. Application to DI Gasoline Engines.

An instrument to measure time-resolved fuel-air ratios in the vicinity of a spark plug was developed. Absorption and scattering at the wavelengths of visible and infrared rays were utilized to determine the fuel-air ratios in the mixture including liquid and vaporized fuel. The measurement error of the instrument was estimated within 10% from comparison between the overall and the measured fuel-air ratios at the vicinity of the spark plug with inlet port injection which froms homogeneous mixture. The instrument was applied to direct injection gasoline engines and the mixture formation process was discussed.