Ti-Al系燃焼合成における自己着火温度に及ぼす主要パラメタの影響(熱工学,内燃機関,動力など)

Abstract

Relevant to materials synthesis by combustion, spontaneous ignition of compacted mixture has been examined with Ti-Al system taken as a research object. Not only experimental but also theoretical study has been conducted, after confirming that the size ratio, defined as the ratio of compact diameter and particle diameter, and the aspect ratio, defined as the ratio of compact height and diameter, can be useful parameters in correlating experimental results. It is found that with increasing aspect ratio and/or size ratio, the spontaneous ignition temperature decreases within the present experimental conditions, below the melting point 934K of Al. The decrease with increasing aspect ratio is attributed to an establishment of the stationary temperature distribution in the compacted mixture, being balanced between heat release and loss. The decrease with increasing size ratio is attributed to an increase in the particle surface per unit spatial volume of compacted mixture. Effects of mixture ratio have also been examined, showing that the spontaneous ignition temperature decreases with increasing mixture ratio. Effects of the degree of dilution on the spontaneous ignition temperature are also examined. Experimental comparisons with theoretical results have also been conducted and a fair degree of agreement is demonstrated, indicating that the present formulation has captured the essential features of the spontaneous ignition of compacted mixture.