한국가시화정보학회:학술대회논문집

The Korean Society of Visualization (한국가시화정보학회)
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Self-Excited Noise Generation from Laminar Methane/Air Premixed Flames in Thin Annular Jets

  • Kim K. N. (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Joung J. H. (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Jin S. H. (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Chung S. H. (School of Mechanical and Aerospace Engineering, Seoul National University)
  • Published : 2004.12.01
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Abstract

Self-excited noise generation from laminar flames in thin annular jets of methane/air premixture has been investigated experimentally. Various flames were observed in this flow configuration, including conical shape flames, ring shape flames, steady crown shape flames, and oscillating crown shape flames. Self-excited noise with the total sound pressure level of about 70dB was generated from the oscillating crown shape flames for the equivalence ratio larger than 0.95. Sound pressure and $CH^*$ chemiluminescence were measured by using a microphone and a photomultiplier tube. The frequency of generated noise was measured as functions of equivalence ratio and premixture velocity. A frequency doubling phenomena have also been observed. The flame shape during flame oscillation was reconfirmed by a synchronized PIV experiment. The velocity and pressure field were obtained from PIV. The minimum pressure was formed near the edge of flame representing circulation. By comparing the results of sound pressure, flame luminosity and PIV, the noise source can be attributed to the flame front fluctuation near the edge of the oscillating crown-shape flames.

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