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Experimental investigation of the effects of hydrogen addition on the dynamics of turbulent premixed flames

With an ever increasing need for the reduction of carbon and nitrogen based emissions, gas turbine technology has evolved over the years. Lean burning (i.e. high air to fuel ratio) has proven to be an effective method in reducing the nitrous oxide emissions. However, these flames are susceptible to combustion oscillations that could lead to excessive heat transfer, oscillatory thermal and mechanical stresses and flame blow-off or flashback. The addition of hydrogen fuel to turbulent flames has been studied in the past and been reported to have reduced combustion oscillations and nitrous oxide formation, however, there are studies in literature that show combustion oscillations triggered by the addition of hydrogen. This project aimed to further investigate the effects of local hydrogen addition on the dynamics of turbulent lean premixed flames in a model gas turbine combustor. The flames were subjected to controlled reactant mass flow oscillations (created by acoustic speakers) that led to flame surface roll-up, thus causing heat release perturbations (i.e. combustion oscillations). Under these conditions hydrogen fuel was locally added into the flow to study the effects on the response of the flame. A secondary objective was to develop a laser technique for imaging the laser induced fluorescence of atomic hydrogen in turbulent flames. While earlier studies had only focused on laminar flames, this project concentrated on imaging large sections of turbulent premixed flames which were subjected to acoustic forcing. The results showed that the local addition of hydrogen reduced the heat release oscillations of the flame under certain operating conditions. The change in the response of the flame was due to the alteration of the flame surface area. While there were benefits of reducing heat release oscillations, the addition of hydrogen to the flame had a negative impact on the nitrous oxide exhaust emissions.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:632112
Date January 2014
CreatorsHussain, T.
PublisherUniversity College London (University of London)
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Sourcehttp://discovery.ucl.ac.uk/1456277/

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