Effect of geometrical parameters on thermo-acoustic instability of downward propagating flames in tubes

被引：15

作者：

Dubey, Ajit Kumar ^{[1
]}

Koyama, Yoichiro ^{[1
]}

Hashimoto, Nozomu ^{[1
]}

Fujita, Osamu ^{[1
]}

机构：

[1] Hokkaido Univ, Div Mech & Space Engn, Kita Ku, Kita 13 Nishi 8, Sapporo, Hokkaido 9308555, Japan

来源：

PROCEEDINGS OF THE COMBUSTION INSTITUTE | 2019年 / 37卷 / 02期

关键词：

Thermo-acoustic instability; Downward propagating flames; Combustion tube; Effect of geometrical parameters; VIBRATORY INSTABILITY; UNSTEADY RESPONSE; PREMIXED-FLAMES; HYDROGEN;

D O I：

10.1016/j.proci.2018.06.155

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

Experiments and theoretical analysis are presented to clarify the effect of geometrical parameters on thermoacoustic instability of downward propagating flames in tubes. The experiments reveal that the longer tubes have higher instability compared to shorter tubes and the lower diameter tubes have higher instability compared to higher diameter tubes. The secondary instability leading to turbulent burning is found to be more sensitive to change in geometrical parameters compared to primary instability (oscillating flat flame). The secondary instability is re-stabilized for some intermediate burning velocity conditions even though lower and higher burning velocity conditions show secondary instability. The appearance of such re-stabilization is only observed for some specific lengths of the tube. Present experimental observations pertaining to the effect of geometrical parameters is found to be contradicting the theoretical predictions based on pressure coupling mechanism. To clear the underlying mechanism, analytical growth rate is computed considering velocity coupling mechanism. The computed growth rates correctly predict the effect of geometrical parameters on thermo-acoustic instability of downward propagating flames. This work provides further evidence to believe that the flame -acoustic coupling in downward propagating flames is due to flame area modulation (leading to heat release modulation) through action of acoustic acceleration. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

引用

页码：1869 / 1877

页数：9

共 30 条

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