Experimental Study on the Combustion and Microexplosion of Freely Falling Gelled Unsymmetrical Dimethylhydrazine (UDMH) Fuel Droplets

Zejun Liu, Xiaoping Hu, Zhen He and Jianjun Wu
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Zejun Liu: College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China
Xiaoping Hu: College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China
Zhen He: College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China
Jianjun Wu: College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China

Energies, 2012, vol. 5, issue 8, 1-11

Abstract: The increasing demand for high energy density fuels and the concern for their safety have propelled research in the field of gelled propellants, where understanding the combustion of single gelled fuel droplets is the first stage to predict the spray combustion characteristics. The experiments utilized single-isolated freely falling gelled unsymmetrical dimethylhydrazine (UDMH) droplets instead of the conventional suspended droplet approach, in order to eliminate the perturbation associated with the suspension mechanism. Morphological transformations of the gelled droplet involved in the combustion processes were monitored by employing a high-speed digital camera, while the effects of ambient pressure and oxygen concentration on burning rate constants were also studied. The experimental results show that four main phenomena (droplet deformation, bubble formation and growth, vapor jetting and luminous jetting flame with “horn” shape) and three distinct phases were identified in the droplet combustion process; the high yield stress and polymer chain structure of polymer gellant are responsible for the appearance of bubbles with almost the same order of magnitude as the droplets. Increasing the ambient pressure can increase the burning rate, postpone the appearance of microexplosions, and weaken microexplosion intensity; while increasing the ambient oxygen concentration can promote the appearance of microexplosions, strengthen microexplosion intensity and increase the burning rate.

Keywords: gelled UDMH fuel; droplet combustion; microexplosion; burning rate constant (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2012
References: View complete reference list from CitEc
Citations: View citations in EconPapers (7)

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