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

A Novel Damping Device for Broadband Attenuation of Low-Frequency Combustion Pulsations in Gas Turbines

[+] Author and Article Information
Mirko R. Bothien

e-mail: mirko.bothien@power.alstom.com

Bruno Schuermans

5401 Baden, Switzerland

The acoustic impedance Z is related to the reflection coefficient R by the bilinear transform Z/ρc=(1+R)/(1-R).

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 August 16, 2013; final manuscript received August 26, 2013; published online December 10, 2013. Editor: David Wisler.

J. Eng. Gas Turbines Power 136(4), 041504 (Dec 10, 2013) (9 pages) Paper No: GTP-13-1310; doi: 10.1115/1.4025761 History: Received August 16, 2013; Revised August 26, 2013

Damping of thermoacoustically induced pressure pulsations in combustion chambers is a major focus of gas turbine operation. Conventional Helmholtz resonators are an excellent means to attenuate thermoacoustic instabilities in gas turbines. Usually, however, the damping optimum is in a narrow frequency band at one operating condition. The work presented here deals with a modification of the basic Helmholtz resonator design overcoming this drawback. It consists of a damper body housing multiple volumes that are connected to each other. Adequate adjustment of the governing parameters results in a broadband damping characteristic for low frequencies. In this way, changes in operating conditions and engine-to-engine variations involving shifts in the combustion pulsation frequency can conveniently be addressed. Genetic algorithms and optimization strategies are used to derive these parameters in a multidimensional parameter space. The novel damper concept is described in more detail and compared with cold-flow experiments. In order to validate the performance under realistic conditions, the new broadband dampers were implemented in a full-scale test engine. Pulsation amplitudes could be reduced by more than 80%. In addition, it is shown that, due to sophisticated damper placement in the engine, two unstable modes can be addressed simultaneously. Application of the damper concept allowed a considerable increase of the engine operating range, thereby reducing NOx emissions by 55%. Predictions obtained with the physics-based model excellently agree with experimental results for all tested damper geometries, bias flows, excitation amplitudes, and most importantly with the measurements in the engine.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Fig. 1

Schematic block diagram for the damper model

Grahic Jump Location
Fig. 2

Schematic of measurement setup in cold-flow acoustic test facility

Grahic Jump Location
Fig. 3

Comparison of measured reflection coefficients (dashed with ×) and model (solid) for different geometries (a)–(c); top: magnitude, bottom: phase. From red to blue, the ratio between most downstream to most upstream volume decreases.

Grahic Jump Location
Fig. 4

Comparison of measured reflection coefficients (dashed with symbols) and model (solid) for different excitation amplitudes; top: magnitude, bottom: phase

Grahic Jump Location
Fig. 5

Comparison of measured reflection coefficients (dashed with symbols) and model (solid) for different bias flow velocities; top: magnitude, bottom: phase

Grahic Jump Location
Fig. 6

Isosurfaces of damping performance versus combination of geometry parameters P1, P2, and P3. Red (gray) isosurface: 95% (90%) of maximum growth rate reduction.

Grahic Jump Location
Fig. 7

Comparison of ratios of acoustic pressures inside HHD and combustion chamber for measurement (solid) and sixth order model (dashed). Top: magnitude, bottom: phase.

Grahic Jump Location
Fig. 8

Normalized growth rate versus normalized frequency for system without dampers (), equipped with single-volume (°), and multivolume (□) dampers

Grahic Jump Location
Fig. 9

Comparison of reflection coefficients for single-volume (dashed) and multivolume (solid) damper; top: magnitude, bottom: phase

Grahic Jump Location
Fig. 10

Normalized frequency of critical mode without dampers and NOx versus operating parameters A and B. Top: operating window of engine without dampers. Middle: enlarged operating window by using dampers. Bottom: normalized NOx improvement at B3 using dampers.

Grahic Jump Location
Fig. 11

Averaged spectra of scaled acoustic pressure p∧/p∧max for two different operating conditions

Grahic Jump Location
Fig. 12

C2n values for distributions 1–6 of damper configuration B. Solid with ×: third azimuthal mode, dashed with °: first azimuthal mode. The values are scaled with the maximum C2n for the respective mode.




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