Progress in the Measurement of Thermoacoustic Oscillations in the Combustion Field of Gas Turbines
Hydrogen-fueled gas turbines are the most promising research direction at present.Although hydrogen fuel,especially green hydrogen energy,can lower greenhouse gas emissions and enhance energy efficiency,the thermoacoustic oscillation phenomena are easily generated by hydrogen energy's high combustion rate and quick chemical reaction rate during combustion.The coupling of an acoustic wave and heat release at a phase difference of less than 90° results in thermoacoustic oscillation,which can wear down a gas turbine and even harm its components.Flame heat release variation,acoustic pressure pulsation,flow field fluctuation in the combustion chamber,etc.are some of the sources of thermoacoustic oscillation.The coupling analysis of these variables can increase our comprehension of thermoacoustic oscillation and give us a theoretical foundation for forecasting it.The parameters used in the research of thermoacoustic oscillations include dynamic pressure,flame heat release,temperature,equivalent ratio,and velocity,and the related test techniques should be capable of high-frequency measurements of them.The measurement means of dynamic pressure mainly include pressure sensors and microphones.Due to the fast time domain response and obvious dynamic characteristics of pressure,it is the key parameter of the thermoacoustic coupling effect and is most widely studied.OH,chemiluminescence,or fluorescence signals are mostly used to characterize the flame heat release,and the measurement methods include Intensified CCD(ICCD),a photomultiplier tube(PMT),planar-laser-induced fluorescence(PLIF),etc.Tunable diode laser absorption spectroscopy(TDLAS),PLIF,Raman spectroscopy(RS),and other optical diagnostic techniques for temperature measurement are available in addition to the widely used thermocouples.Since the equivalence ratio directly impacts combustion parameters,it is challenging to measure dynamic changes in the equivalence ratio using conventional methods like flue gas analyzers.TDLAS,PLIF,laser-induced breakdown spectroscopy(LIBS),and other optical measurement techniques were later developed,and they are all capable of obtaining dynamic changes in the equivalence ratio.Velocity pulsation is a parametric quantity that acts directly on thermoacoustic oscillations,and measurement techniques include one-dimensional dual microphone velocimetry,hot-wire anemometry,laser Dopplervelocimetry(LDV),and multi-dimensional particle image velocimetry measurement(PIV),schlieren,etc.So far,most of the techniques on thermoacoustic oscillation measurement are relatively well developed.This paper lists the principles of these combustion diagnostic techniques and their applications to thermoacoustic oscillation or unstable combustion phenomena,and summarizes the development and prospects of thermoacoustic oscillation measurement.
Gas turbineThermoacoustic oscillationAbsorption spectroscopyRadiation spectroscopyScattering spectroscopy
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维普
