Effects of nozzle length on flame and emission behaviors of multi-fuel-jet inverse diffusion flame burner

H. S. Zhen, Yat Sze Choy, Chun Wah Leung, Chun Shun Cheung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

46 Citations (Scopus)


An experimental study was performed to investigate the effects of the nozzle length on the air-pollutant-emission and noise-radiation behaviors of a burner utilizing a multi-fuel-jet inverse diffusion flame (MIDF). Comparison of the experimental results obtained from two MIDF burners, one with a long nozzle and the other with a short nozzle, operating under the same air/fuel supply conditions (Reairand F{cyrillic}) shows rather significant differences in the flame appearance, flame centerline temperature, CO/CO2concentrations and the noise radiation. The nozzle length influences development of the jets and hence interaction between the air/fuel jets including their mixing process. The short nozzle produces a flame with a shorter base height and a smaller potential core due to the enhanced air/fuel mixing. It also leads to faster and more complete combustion at the inner reaction cone of the flame due to the stronger and faster air/fuel mixing. The nozzle length affects the CO and CO2concentrations, and higher peak values are obtained with the short-nozzle flame. Flame noise of the MIDF is defined as the noise radiation at different flame heights, which is of varying strength but of the same dominant frequency in the range of 250-700Hz. The noise radiation from the inner reaction cone of the flame is stronger than that from the lower and upper parts of the flame, and the maximum noise radiation occurs when the total amounts of air and fuel in the combustion zone are at the stoichiometric air/fuel ratio. For all the experiments conducted in the present study, the MIDF produced by the long nozzle is always noisier than its counterpart and it is due to the increase of the low-frequency noise components.
Original languageEnglish
Pages (from-to)2917-2924
Number of pages8
JournalApplied Energy
Issue number9
Publication statusPublished - 1 Jan 2011


  • Air/LPG combustion
  • Burner design
  • Flame noise radiation
  • Inverse diffusion flame

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Energy(all)


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