Release of chemical energy by combustion in a supersonic mixing layer of hydrogen and air

Tien J.H. and Stalker R.J. (2002) Release of chemical energy by combustion in a supersonic mixing layer of hydrogen and air. Combustion and Flame, 131 3: 329-348. doi:10.1016/S0010-2180(02)00371-1


Author Tien J.H.
Stalker R.J.
Title Release of chemical energy by combustion in a supersonic mixing layer of hydrogen and air
Journal name Combustion and Flame   Check publisher's open access policy
ISSN 0010-2180
Publication date 2002-11-01
Sub-type Article (original research)
DOI 10.1016/S0010-2180(02)00371-1
Volume 131
Issue 3
Start page 329
End page 348
Total pages 20
Subject 2102 Curatorial and Related Studies
2103 Historical Studies
2210 Mechanical Engineering
Abstract The process involved in chemical energy release by combustion in a supersonic, constant pressure, hydrogen-air laminar mixing layer was studied computationally, with a chemical kinetics model involving nineteen reactions and eight species. To try to find out the physical reason for the different trends of the pressure curves observed in an experimental supersonic combustor at two different initial air stream temperatures. Two initial air stream temperatures corresponding to the two experimental cases are chosen such that the higher temperature yielded a shorter ignition distance, and the lower temperature yielded a longer ignition distance. For both cases the stream wise rate of energy release rises rapidly to a peak after ignition then falls to a post-ignition value which decreases very slowly with distance. A single premixed flame occurs at ignition for both cases, but then develops into a triple flame structure in the high temperature case, and a flame with only two branches in the low temperature case. The flames move from the airside to hydrogen side consuming the oxygen as they go, until the post-ignition phase is reached. There the dominant energy release arises from the formation of a diffusion flame. In the high temperature case a narrow lean premixed flame accompanies this diffusion flame on the airside. The flame structure, but not the energy release, is effected by the initial temperature distribution across the mixing layer, which is found to be influenced by the velocity difference between the faster air stream and the slower hydrogen stream. Increasing the concentration of oxygen atoms in the oncoming air stream was found to cause substantial reduction in the ignition distance, but did not significantly effect the flame structure, or the rate of heat release in the post-ignition phase. Finally, the different trends of pressure curves observed in the experiment can be reconstructed when pressure variation was considered in this model. Thus we can conclude that the difference in the trends of the pressure curves is caused by the difference in the initial air stream temperature.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import
 
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