Combustion oscillations in bluff body stabilized diffusion flames with variable length inlet

M. Madanmohan, S. Pandey, A. Kushari, K. Ramamurthi

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


This paper describes the results of an experimental study to understand the influence of inlet flow disturbances on the dynamics of combustion process in bluff body stabilized diffusion flames of liquid petroleum gas and air. The results show the influence of weak disturbances created by the change in incoming pipe length on the amplitude of pressure oscillations and the phase angle between pressure and heat release. It is seen that the phase delay increases as the entry length increases. The rms value of pressure, however, generally falls with the increase in length. The phase angle is seen to be in the second quadrant, showing that the heat release oscillations damp the pressure oscillations. Therefore, the decrease in the phase angle results in the reduction in damping and hence an increase in pressure fluctuations. The dominant frequencies of combustion oscillations are found to be the low frequency oscillations, and the frequency of oscillations increases with a decrease in the inlet pipe length and an increase in the flow Reynolds number. It is suggested that such low frequency oscillations are driven by vortex shedding at the wake of the bluff body, which energizes the diffusion and mixing process.

Original languageEnglish
Article number054501
JournalJournal of Engineering for Gas Turbines and Power
Issue number5
StatePublished - 1 Sep 2009
Externally publishedYes


  • Bluff body stabilization
  • Combustion instability
  • Diffusion flames

ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Fuel Technology
  • Aerospace Engineering
  • Energy Engineering and Power Technology
  • Mechanical Engineering


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