LARGE EDDY SIMULATION OF REAL COMBUSTORS

CNRS/Inst. de Mecanique des Fluides de Toulouse Toulouse, Prance 

The examples presented in this chapter [308 320] are illustrations of the concepts presented in the previous chapters. They correspond to recent numerical analysis of burners which are typical of most modern high-power combustion chambers, especially of gas turbines the flame is stabilized by strongly swirled flows, the Reynolds numbers are large, the flow field sensitivity to boundary conditions is high, intense acoustic/combustion coupling can lead to self-sustained oscillations. Flames are stabilized by swirl. Swirl also creates specific flow patterns (a Central Toroidal Recirculation Zone called CTRZ) and instabilities (the Precessing Vortex Core called PVC). 

The first example is a small-scale laboratory combustor using an aeroengine gas turbine burner (power 30 kW) while the second one corresponds to a laboratory-scale staged burner in which self-excited instabilities can be easily triggered by changing the outlet acoustic boundary conditions. In staged combustors, fuel and air are premixed but they are introduced into the chamber at different locations and different equivalence ratios so that partially premixed flames are found inside the burner. All combustors are operated at atmospheric pressure. 

The flame/turbulence interaction model is the thickened flame model [269] and boundary conditions are specified using the NSCBC method [339 329[. The turbulence model is the Smagorinski model or the Wale model [330[. 

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