Mixing and stabilization study of a partially premixed swirling flame using laser induced fluorescence
- Ecole Centrale Paris, Laboratoire EM2C, CNRS, Chatenay Malabry (France)
A laboratory-scale swirling burner, presenting many similarities with gas turbines combustors, has been studied experimentally using planar laser induced fluorescence (PLIF) on OH radical and acetone vapor in order to characterize the flame stabilization process. These diagnostics show that the stabilization point rotates in the combustion chamber and that air and fuel mixing is not complete at the end of the mixing tube. Fuel mass fraction decays exponentially along the mixing tube axis and transverse profiles show a gaussian shape. However, radial pressure gradients tend to trap the fuel in the core of the vortex that propagates axially in the mixing tube. As the mixing tube vortex enters the combustion chamber, vortex breakdown occurs through a precessing vortex core (PVC). The axially propagating vortex shows a helicoidal trajectory in the combustion chamber which trace is observed with transverse acetone PLIF. As a consequence, the stabilizing point of the flame in the combustion chamber rotates with the PVC structure. This phenomenon has been observed in the present study with a high speed camera recording spontaneous emission of the flame. The stabilization point rotation frequency tends to increase with mass flow rates. It was also shown that the coupling between the PVC and the flame stabilization occurs via mixing, explaining one possible coupling mechanism between acoustic waves in the flow and the reaction rate. This path may also be envisaged for flashback, an issue that will be more completely treated in a near future. (author)
- OSTI ID:
- 21396168
- Journal Information:
- Combustion and Flame, Vol. 158, Issue 1; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GAS TURBINES
MIXING
ACETONE
FLAMES
STABILIZATION
COMBUSTION CHAMBERS
VORTICES
TUBES
AIR
FUELS
VAPORS
HYDROXYL RADICALS
COMBUSTION KINETICS
COUPLING
MASS
ROTATION
FLOW RATE
PRESSURE GRADIENTS
SOUND WAVES
BURNERS
COMBUSTORS
SHAPE
TRAJECTORIES
TRAPS
VELOCITY
VORTEX FLOW