Acoustic Emission of Thermodiffusive Unstable Hydrogen-Air Flames

  • Pedro Beltran, Borja (RWTH Aachen)
  • Meinke, Matthias (RWTH Aachen)
  • Schröder, Wolfgang (RWTH Aachen)

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Combustion noise is always coupled to the fluctuations of the flow field variables. The temporal fluctuation of the heat release is a direct noise source term, caused by perturbations of the flame surface generated by velocity fluctuations, which, in turn, are caused by the acoustic field or turbulent scales. In this context, extensive research has already been performed to understand the underlying mechanisms involved in the acoustic emission and coupling of premixed methane-air flames. However, the thermoacoustic analysis of lean hydrogen-air flames is a rather novel research field, and the mechanisms involved in acoustic emission and its overall impact remain unanswered. As an effect of flame-flow interaction, the flame front perturbations are damped or fanned by intrinsic stability phenomena. In addition to the mechanisms involved in the flame front stabilization of methane-air flames, preferential diffusion and non-unity Lewis-number effect have a significant impact on the flame dynamics, which could influence the acoustic emission of hydrogen-air lean premixed flames.