A Comparative Study Between Diffusive-thermal and Buoyancy-driven Self-excitations in Laminar Free Jet Flames with Applied DC Electric Fields

직류전기장이 인가된 층류제트화염에서 물질 -열 확산과 부력에 의한 진동비교에 관한 연구

  • 한종규 (부경대학교 기계공학과) ;
  • 윤성환 (부경대학교 친환경 수송시스템연구소) ;
  • 박정 (부경대학교 기계공학과) ;
  • 권오붕 (부경대학교 기계공학과) ;
  • 김태형 (한국전력연구원 수화력 발전팀) ;
  • 박종호 (충남대학교 기계공학과)
  • Received : 2012.02.17
  • Accepted : 2012.03.21
  • Published : 2012.03.30

Abstract

Experimental study on comparison of diffusive-thermal self-excitation with buoyancy-driven one due to accumulation of partially premixed, preheated mixture in front of edge flame was conducted in horizontally and vertically injected laminar free-jet flames with an applied DC electric field of -10 kV. The application of horizontal injection method with the DC electric field to jet flames was experimentally designed to suppress heat-loss-induced self-excitation and thereby to highlight the definite difference between both diffusive-thermal and buoyancy-driven self-excitations with the same order of O(1.0 Hz), in that diffusive-thermal self-excitation has not been so far found experimentally in laminar jet flames. Flame stability maps in vertically and horizontally injected jet flames are presented. The distinct modes of individual self-excitation are shown to be well described by their own phase diagrams. The results show that buoyancy-driven self-excitation due to the accumulation of partially premixed, preheated mixtures in front of edge flame is branched from the buoyancy-induced self-excitation with O(10 Hz) due to a flame flicker. Once the buoyancy-driven self-excitation appears, it suppresses buoyancy-induced as well as diffusive-thermal self-excitation. The key characteristics for individual self-excitation are discussed and their functional dependencies of Strouhal number upon related physical parameters are also presented.

Acknowledgement

Supported by : 한국연구재단

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