Acoustically Induced Flashback in a Staged Swirl-Stabilized Combustor
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- 作者：Corentin J. Lapeyre ; Marek Mazur ; Philippe Scouflaire…
- 关键词：Flashback ; Flame stabilization ; Thermoacoustic instabilities ; Experimental combustion ; LES
- 刊名：Flow, Turbulence and Combustion
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：98
- 期：1
- 页码：265-282
- 全文大小：
- 刊物类别：Engineering
- 刊物主题：Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer; Automotive Engineering;
- 出版者：Springer Netherlands
- ISSN：1573-1987
- 卷排序：98
文摘
This paper describes a joint experimental and numerical investigation of the interaction between thermoacoustics and flashback mechanisms in a swirled turbulent burner. An academic air/propane combustor terminated by a choked nozzle is operated up to 2.5 bars. Experiments show that the flame can stabilize either within the combustion chamber or flashback inside the injection duct, intermittently or permanently. The present study focuses on the mechanisms leading to flashback: this phenomenon can occur naturally, depending on the swirl level which can be adjusted in the experiment by introducing axial flow through the upstream inlet. It can also be triggered by acoustic waves, either through acoustic forcing or self-excited thermoacoustic instability. Flashback is difficult to study experimentally, but it can be investigated numerically using LES: in a first configuration, the outlet of the chamber is treated as a non-reflecting surface through which harmonic waves can be introduced. In this case, a 20 kPa acoustic forcing is sufficient to trigger permanent flashback after a few cycles. When the LES computational domain includes the choked nozzle used experimentally, no forcing is needed for flashback to occur. Self-excited oscillations reach high levels rapidly, leading to flame flashback, as observed experimentally. These results also suggest a simple method to avoid flashback by using fuel staging, which is then tested successfully in both LES and experiments.