Analytical modelling of flame transfer functions for technically premixed flames

The linear response to harmonic acoustic excitation of the total heat release rate in technically premixed flames (Flame Transfer Function, FTF) is studied case an ideal swirl burner. analysis based on linearization production for mean reaction progress variable modelled with a turbulent flame speed closure. Three main components FTF are identified which generated by: I) direct fluctuations fuel mixture fraction (formation enthalpy contribution), II) and III) surface area driven by velocity fluctuations. fluctuation separated into irrotational displacement rotational convective component. effect component here semi-empirical way, related number at base due phase shift between convected tangential acoustically propagating axial It finally shown that can be not only air mass flow but also depend upon side impedance injection location. this changes geometry plenum placed upstream burner affecting way FTF.