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Title: Imaging based studies of premixed flame propagation in tubes
Author: Jiang, Houshi
ISNI:       0000 0004 9356 9406
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2020
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The dynamics of flames occurring in a confined space represent a typical combustion process in an internal combustion engine, as well as the process of flame acceleration and the transition from deflagration to detonation in the development of detonation waves. Therefore, these dynamics have significant applications in the areas of combustion engineering and explosion safety. Due to a global desire for clean energy resources—and because combustible gases are clean and come from a wide range of sources—these gases are beginning to play an indispensable role in industrial modernisation and in people's daily lives. Hydrogen, especially, can be produced using renewable electricity such as offshore wind power. This increases the availability of hydrogen resources and reduces their cost. This research will major on the hydrogen effects of premixed flame propagation in a confined space: a tube. It will utilise optical measurement methods to investigate how the dynamic characteristics of premixed flame propagation change, within a tube. The experiment provides a safe and controlled way to understand the process of flame propagation. The originality of this research comes from studying how hydrogen affects the flame propagation interaction in a classic hydrocarbon mixture of methane/air, in both horizontal and vertical tubes. Another innovation is that of applying two different optical measurement methods (flame chemiluminescence and schlieren imaging) at the same time, to capture both flame chemistry and flame flow. First, the interesting interaction between the C2 * emissions and pressure, with hydrogen addition, was found in the horizontal tube. The measured C2 * emissions had similar fluctuations with the measured pressure, as the flame traversed down the tube. The results indicated a coupling interaction between the C2 * flame chemiluminescence and the pressure. Second, hydrogen concentration, affecting flame speed at the second stage of flame propagation in a vertical tube, was also discussed. The flame propagation speed was faster, with higher hydrogen concentrations, at the same equivalence ratios in fuel-rich conditions. The ratio of two oscillation gradient stage (oscillation gradient stage to the initial gradient stage), decreased linearly as the hydrogen concentration increased. Finally, to develop the mechanisms of flame formation, schlieren imaging techniques were applied at flame propagation in a square tube. Following the results of the schlieren images and pressure signals, periodic propagation characteristics were observed around the middle length of the tube. Each cycle included a flat or curved flame front, a cellular or cells flame front, two near-boundary sides of the tulip flame, a flat or curved flame at the front again, a cellular or cells flame at the front again and a tulip flame in the middle of the tube.
Supervisor: Zhang, Yang ; Woolley, Robert Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Thesis
EThOS ID:  DOI: Not available