研究発表

予混合気に不均質性を与えることでHCCIの急峻な圧力上昇を回避する手法について検証する．本研究では，急速圧縮装置を用いて温度の不均質性がHCCI燃焼過程に与える影響について調査した． 急速圧縮装置の燃焼室内に燃料と空気の予混合気を充填して，層状の温度分布を形成した場合としない場合について，圧縮自己着火燃焼時の発光画像をフレーミングカメラを用いて観測するとともに燃焼室内ガスの圧力履歴を計測・解析した．

The Homogeneous Charge Compression Ignition (HCCI) engine is possible to achieve high thermal efficiency and low emissions. One of the main challenges with HCCI engines is structuring the systems to control combustion phasing, crank angle of 50% heat release (CA50), for keeping high thermal efficiency and avoiding an excessive rate of pressure rise which causes knocking, when operating conditions vary. Though some HCCI combustion control systems, for example Variable Valve Timing System and Variable Compression Ratio System, have been suggested, these control systems are complex and heavy.

The purpose of this study was to gain a better understanding of the effects of in-cylinder gas temperature stratification on reducing the pressure-rise rate in HCCI combustion. HCCI combustion was investigated using an optically accessible engine and direct visualization of the combustion chemiluminescence. The engine was fueled with Di-Methyl Ether. Computational work was conducted on the gas compression and expansion strokes in HCCI engine with simple 0-dimensinal multi-zones model.