A practical application of the bode criterion for prediction of thermoacoustic combustion instabilities

J. A. Ranalli, C. R. Martin, U. Vandsburger

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The work presented summarizes a simplified approach to prediction of thermoacoustic instabilities employed at Virginia Tech, based on a control system model of a lean-premixed turbulent combustor. Separate transfer functions representing the flame dynamics and the combustor acoustics were measured. Though the transfer functions used in this work were experimentally obtained, in concept, flame and acoustic transfer functions obtained from theoretical means would have also been suitable. The acoustic transfer function was considered to be constant with respect to operating condition, while flame transfer function variations were realized by generating a prototype flame transfer function from experimental flame transfer function data. The flame and acoustic transfer functions were then combined in a closed loop system model to obtain the system open loop transfer function (OLTF), representing the closed loop feedback between the flame and the acoustics. The OLTF was analyzed using the Bode criterion, which tests for amplifying gain at frequencies where the acoustic and flame oscillations occur in phase. The gain margin was used when necessary as an additional criterion to select single prediction of instability at each given operating condition. Predictions were then validated in a laboratory combustor and showed reasonable accuracy in identifying frequencies at which instabilities occurred.

Original languageEnglish (US)
Title of host publicationFall Meeting of the Eastern States Section of the Combustion Institute 2009
PublisherCombustion Institute
Pages1-8
Number of pages8
ISBN (Electronic)9781615676682
StatePublished - Jan 1 2009
EventFall Meeting of the Eastern States Section of the Combustion Institute 2009 - College Park, United States
Duration: Oct 18 2009Oct 21 2009

Publication series

NameFall Meeting of the Eastern States Section of the Combustion Institute 2009

Other

OtherFall Meeting of the Eastern States Section of the Combustion Institute 2009
CountryUnited States
CityCollege Park
Period10/18/0910/21/09

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

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