Case 2 Self-Excited Staged Burner

3 Case 2 Self-Excited Staged Burner Configuration 

Total flow rate (kg/s) Mean equivalence ratio a / i 4 2 

When the outlet is non-reflecting, the flame is stable. The mean axial velocity and fuel mass fraction fields are displayed in Fig. 9.15 and 9.16 [320] the central recirculation zone (marked by a white line in Fig. 9.15) is filled by burnt gases which provide flame stabilization. Fuel staging is also apparent in Fig. 9.16. 

During these phases, the total acoustic energy is extracted from LES. Fig. 9.17 shows that it first grows, becomes maximum and then decreases slightly to reach a limit cycle at a frequency of 360 Hz mode which is one of the acoustic modes of the combustor [320]. After t = 0.173 s, when the outlet becomes non reflecting again, it decays rapidly. 

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