水素微小球状伝ぱ層流火炎の燃焼速度特性に及ぼす化学反応特性時間の影響

概要

論文の詳細を見る
Comprehension of the burning velocity for micro-scale flames is inevitable in the improved design of micro-combustors for miniaturized power supplies. The present study is performed to examine experimentally the burning velocity characteristics of hydrogen-premixed micro-scale spherical laminar flames in the range of flame radius rf < 5 mm, and also macro-scale laminar flames with rf > 7 mm for comparison. The mixtures have nearly the laminar burning velocity SL0 at so-called unstretched flames with different equivalence ratios (φ=0.3-1.2). In this experiment, the values of the SL0 are fixed at approximately 15, 25 and 35 cm/s, in order to examine the influence of characteristic chemical reaction time on micro-scale spherical laminar flames. The radius and the burning velocity of micro-scale flames are obtained by using sequential schlieren images recorded under appropriate ignition conditions. The results show that the burning velocities of micro-scale flames with φ=0.3 and 0.5 or 1.2 have a tendency to decrease or increase with increasing rf and approach that of macro-scale flames, but such a trend can not be seen for φ0.7 and 0.9 micro-scale flames, irrespective of SL0. It is also found that the optimum size and Karlovitz number to improve the burning velocity are existed for φ0.7 and 0.9 micro-scale flames, irrespective of SL0.