Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

An Acoustic Time-of-Flight Approach for Unsteady Temperature Measurements: Characterization of Entropy Waves in a Model Gas Turbine Combustor

[+] Author and Article Information
Dominik Wassmer

Chair of Fluid Dynamics,
Technische Universität Berlin,
Müller-Breslau-Str. 8,
Berlin 10623, Germany
e-mail: dominik.wassmer@tu-berlin.de

Bruno Schuermans

GE Power,
Brown-Boveri-Str. 7,
Baden 5401, Switzerland
e-mail: bruno.schuermans@ge.com

Christian Oliver Paschereit

Chair of Fluid Dynamics,
Technische Universität Berlin,
Müller-Breslau-Str. 8,
Berlin 10623, Germany
e-mail: oliver.paschereit@tu-berlin.de

Jonas P. Moeck

Combustion Dynamics,
Technische Universität Berlin,
Müller-Breslau-Str. 8,
Berlin 10623, Germany
e-mail: jonas.moeck@tu-berlin.de

1Corresponding author.

Contributed by the Combustion and Fuels Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 29, 2016; final manuscript received July 28, 2016; published online October 18, 2016. Editor: David Wisler.

J. Eng. Gas Turbines Power 139(4), 041501 (Oct 18, 2016) (8 pages) Paper No: GTP-16-1289; doi: 10.1115/1.4034542 History: Received June 29, 2016; Revised July 28, 2016

Lean premixed combustion promotes the occurrence of thermoacoustic phenomena in gas turbine combustors. One mechanism that contributes to the flame–acoustic interaction is entropy noise. Fluctuations of the equivalence ratio in the mixing section cause the generation of hot spots in the flame. These so-called entropy waves are convectively transported to the first stage of the turbine and generate acoustic waves that travel back to the flame; a thermoacoustic loop is closed. However, due to the lack of experimental tools, a detailed investigation of entropy waves in gas turbine combustion systems has not been possible up to now. This work presents an acoustic time-of-flight based temperature measurement method which allows the measurement of temperature fluctuations in the relevant frequency range. A narrow acoustic pulse is generated with an electric spark discharge close to the combustor wall. The acoustic response is measured at the same axial location with an array of microphones circumferentially distributed around the combustion chamber. The delay in the pulse arrival times corresponds to the line-integrated inverse speed of sound. For the measurement of entropy waves in an atmospheric combustion test rig, fuel is periodically injected into the mixing tube of a premixed combustor. The subsequently generated entropy waves are measured for different forcing frequencies of the fuel injection and for different mean flow velocities in the combustor. The amplitude decay and phase lag of the entropy waves adhere well to a Strouhal number scaling for different mean flow velocities.

Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.


Dowling, A. P. , and Stow, S. R. , 2003, “ Acoustic Analysis of Gas Turbine Combustors,” J. Propul. Power, 19(5), pp. 751–764. [CrossRef]
Marble, F. , and Candel, S. , 1977, “ Acoustic Disturbance From Gas Non-Uniformities Convected Through a Nozzle,” J. Sound Vib., 55(2), pp. 225–243. [CrossRef]
Polifke, W. , Paschereit, C. O. , and Döbbeling, K. , 2001, “ Constructive and Destructive Interference of Acoustic and Entropy Waves in a Premixed Combustor With a Choked Exit,” Int. J. Acoust. Vib., 6(3), pp. 135–146.
Duran, I. , and Moreau, S. , 2013, “ Solution of the Quasi-One-Dimensional Linearized Euler Equations Using Flow Invariants and the Magnus Expansion,” J. Fluid Mech., 723, pp. 190–231. [CrossRef]
Huet, M. , and Giauque, A. , 2013, “ A Nonlinear Model for Indirect Combustion Noise Through a Compact Nozzle,” J. Fluid Mech., 733, pp. 268–301. [CrossRef]
Motheau, E. , Nicoud, F. , and Poinsot, T. , 2014, “ Mixed Acoustic-Entropy Combustion Instabilities in Gas Turbines,” J. Fluid Mech., 749, pp. 542–576. [CrossRef]
Bake, F. , Michel, U. , and Röhle, I. , 2007, “ Investigation of Entropy Noise in Aero-Engine Combustors,” ASME J. Eng. Gas Turbines Power, 129(2), pp. 370–376. [CrossRef]
Dowling, A. P. , and Mahmoudi, Y. , 2015, “ Combustion Noise,” Proc. Combust. Inst., 35(1), pp. 65–100. [CrossRef]
Keller, J. J. , 1995, “ Thermoacoustic Oscillations in Combustion Chambers of Gas Turbines,” AIAA J., 33(12), pp. 2280–2287. [CrossRef]
Sattelmayer, T. , 2002, “ Influence of the Combustor Aerodynamics on Combustion Instabilities From Equivalence Ratio Fluctuations,” ASME J. Eng. Gas Turbines Power, 125(1), pp. 11–19. [CrossRef]
Morgans, A. S. , Goh, C. S. , and Dahan, J. A. , 2013, “ The Dissipation and Shear Dispersion of Entropy Waves in Combustor Thermoacoustics,” J. Fluid Mech., 733, p. R2. [CrossRef]
Strobio Chen, L. , Bomberg, S. , and Polifke, W. , 2016, “ Propagation and Generation of Acoustic and Entropy Waves Across a Moving Flame Front,” Combust. Flame, 166, pp. 170–180. [CrossRef]
Eckstein, J. , 2004, “ On the Mechanisms of Combustion Driven Low-Frequency Oscillations in Aero-Engines,” Ph.D. thesis, TU München, Munich, Germany.
Green, S. F. , 1985, “ An Acoustic Technique for Rapid Temperature Distribution Measurement,” J. Acoust. Soc. Am., 77(2), pp. 759–763. [CrossRef]
Kleppe, J. , Sanchez, J. , and Fralick, G. , 1998, “ The Application of Acoustic Pyrometry to Gas Turbines and Jet Engines,” AIAA Paper No. 98-3611.
Kleppe, J. , Norris, W. , McPherson, D. , and Fralick, G. , 2004, “ The Measurement of Performance of Combustors Using Passive Acoustic Methods,” AIAA Paper No. 2004-1046.
Golub, G. H. , and Loan, C. F. V. , 1996, Matrix Computations, 3rd ed., Johns Hopkins University Press, Baltimore, MD.
Bramanti, M. , Salerno, E. , Tonazzini, A. , Pasini, S. , and Gray, A. , 1996, “ An Acoustic Pyrometer System for Tomographic Thermal Imaging in Power Plant Boilers,” IEEE Trans. Instrum. Meas., 45(1), pp. 159–167. [CrossRef]
DeSilva, U. , Bunce, R. , and Claussen, H. , 2013, “ Novel Gas Turbine Exhaust Temperature Measurement System,” ASME Paper No. GT2013-95152.
Li, J. , Richecoeur, F. , and Schuller, T. , 2013, “ Reconstruction of Heat Release Rate Disturbances Based on Transmission of Ultrasounds: Experiments and Modeling for Perturbed Flames,” Combust. Flame, 160(9), pp. 1779–1788. [CrossRef]
Wyber, R. , 1975, “ The Design of a Spark Discharge Acoustic Impulse Generator,” IEEE Trans. Acoust. Speech Signal Process., 23(2), pp. 157–162. [CrossRef]
Ayrault, C. , Béquin, P. , and Baudin, S. , 2012, “ Characteristics of a Spark Discharge as an Adjustable Acoustic Source for Scale Model Measurements,” Acoustics 2012, Nantes, France, pp. 3549–3553.
Smits, A. J. , Perry, A. E. , and Hoffmann, P. H. , 1978, “ The Response to Temperature Fluctuations of a Constant-Current Hot-Wire Anemometer,” J. Phys. E: Sci. Instrum., 11(9), pp. 909–914. [CrossRef]
Gaetani, P. , Persico, G. , Spinelli, A. , Sandu, C. , and Niculescu, F. , 2015, “ Entropy Wave Generator for Indirect Combustion Noise Experiments in a High-Pressure Turbine,” European Turbomachinery Conference, Madrid, Spain, Mar. 23–27, Vol. 11, Paper No. ETC2015-025.
Li, H. , Wehe, S. D. , and McManus, K. R. , 2011, “ Real-Time Equivalence Ratio Measurements in Gas Turbine Combustors With a Near-Infrared Diode Laser Sensor,” Proc. Combust. Inst., 33(1), pp. 717–724. [CrossRef]
Blümner, R. , Cosic, B. , Paschereit, C. , and Oberleithner, K. , 2016, “ Measurement of Equivalence Ratio Fluctuations in the Mixing Section of a Swirl-Stabilized Burner Using Wavelength Modulation Spectroscopy,” ASME Paper No. GT2016-56585.


Grahic Jump Location
Fig. 1

Principle setup of the TOF method (here: combustion rig setup)

Grahic Jump Location
Fig. 6

Comparison of the steady temperature measurements with thermocouples and the TOF method (top); corresponding relative deviations (bottom)

Grahic Jump Location
Fig. 8

Temperature fluctuation over a 20 Hz period of the injection valve; measured via hot-wire (solid line) and TOF method (dashed line)

Grahic Jump Location
Fig. 9

Equivalence ratio measured in the mixing tube for different valve frequencies and main air mass flows

Grahic Jump Location
Fig. 4

Schematic of the experimental setup for validation

Grahic Jump Location
Fig. 5

Schematic of the combustion chamber setup

Grahic Jump Location
Fig. 7

Hot-wire temperature measurements of one valve injection cycle at 20 Hz at different radial locations; corresponding mean value of thermocouple measurements at different radial locations (horizontal lines)

Grahic Jump Location
Fig. 2

Ceramic adapter and tips of the electrodes as seen from inside the exhaust tube

Grahic Jump Location
Fig. 3

High-pass filtered microphone signals showing the arrival time of the acoustic signal of microphone 3 and microphone 4

Grahic Jump Location
Fig. 11

Phase-averaged TOF measurements over one period of fuel modulation for three different valve frequencies

Grahic Jump Location
Fig. 12

Absolute value (top) and phase (bottom) of the transfer function between the equivalence ratio fluctuation in the mixing tube and the temperature fluctuations at the measurement plane

Grahic Jump Location
Fig. 13

Absolute value (top) and phase (bottom) of the transfer function between the equivalence ratio fluctuation in the mixing tube and the temperature fluctuation at the measurement plane plotted against the Strouhal number

Grahic Jump Location
Fig. 10

Absolute value (top) and phase (bottom) of the transfer function between the valve signal and the equivalence ratio in the mixing tube



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In