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Date
2021Type
- Other Conference Item
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Abstract
The addition of hydrogen fuel to stationary gas turbines presently running on natural gas is an appealing path forward for the reduction of carbon emissions because it can be achieved without dramatic changes to the current power generation infrastructure. Unfortunately, the addition of hydrogen can significantly modify the flame dynamics. One byproduct of such addition is flame flashback, a potentially destructive event wherein the flame exits the combustion section and propagates through the mixing section. Despite the relevancy of boundary layer flashback in practical devices, this phenomenon is generally studied only at low Reynolds numbers, atmospheric conditions, and in non-swirling flows, none of which are representative of conditions in real gas turbines.
In the present work, several open questions regarding boundary layer flashback are addressed through a study of an axial swirl burner at conditions approaching those in practical combustors. Measurements are taken at pressures up to 7.5 bar, preheat temperatures up to 300°C, and inlet velocities up to 40 m/s and are studied in tandem with hydrogen content variations up to 100%. These measurements indicate a significant increase in the flashback propensity with increasing hydrogen concentration. Two distinct flame rotation modes are identified during flashback with the transition occurring as a function of the swirl number. Critically, the flashback limit is shown to occur at a constant extinction strain rate regardless of hydrogen quantity.
These measurements motivate the development of a simple model for boundary layer flashback limits based on critically strained flames. According to the model, the flashback limit occurs at the equivalence ratio where the extinction limit flamespeed matches the mean axial flow velocity one thermal distance from the wall. The model performs extremely well when compared to non-swirling turbulent boundary layer flashback data. It is then extended to study the effect of additional parameters including pressure and hydrogen content on the flashback limit indicating excellent qualitative agreement with the limited available data. Show more
Publication status
publishedBook title
Conference on Combustion Research in Switzerland 2021: Programme & AbstractsPublisher
Bundesamt für Energie BFEEvent
Organisational unit
09471 - Noiray, Nicolas / Noiray, Nicolas
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