Chemical explosive mode analysis of lean blowout in a gas turbine combustor
In this study, stabilization and lean blowout (LBO) mechanisms in a gas turbine combustor are numerically studied based on large eddy simulation (LES) data and the chemical explosive mode analysis (CEMA). Three CEMA-based local combustion modes, that is, auto-ignition, diffusion-assisted ignition, and extinction, are employed to quantify interactions between local diffusion and chemical processes in complex turbulent fields. The capability of CEMA-based local modes in extinction detection is first demonstrated in a one-dimensional non-premixed flamelet undergoing transient extinction. Flame structure and dynamics in the gas turbine combustor are then examined in detail using CEMA and the local combustion modes for both the stably burning and lean blowout conditions. Local structure comprised of all the three modes are identified, and each mode is found to play an important role in determining the overall burning rate. The heat release rate attributed to each local mode remains nearly constant at the stably burning condition. In contrast, the flame during LBO shows a two-stage extinction behavior: at the initial stage, the extinction mode is largely enhanced and becomes dominant over the assisted-ignition model; at the second stage, all three modes are suppressed, signifying global extinction. It is therefore suggested that the excessive local extinction mode, due to an increased amount of heat and radical losses through diffusion, finally leads to lean flame blowout.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- USDOE Office of Science
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1515230
- Country of Publication:
- United States
- Language:
- English
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