0
Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

# An Experimental Investigation of the Nonlinear Response of an Atmospheric Swirl-Stabilized Premixed Flame

[+] Author and Article Information
Sebastian Schimek1

Chair of Fluid Dynamics, Institute of Fluid Dynamics and Technical Acoustics, Hermann-Föttinger-Institut, Technische Universität Berlin, 10623 Berlin, Germanysebastian.schimek@pi.tu-berlin.de

Jonas P. Moeck, Christian Oliver Paschereit

Chair of Fluid Dynamics, Institute of Fluid Dynamics and Technical Acoustics, Hermann-Föttinger-Institut, Technische Universität Berlin, 10623 Berlin, Germany

1

Corresponding author.

J. Eng. Gas Turbines Power 133(10), 101502 (Apr 25, 2011) (7 pages) doi:10.1115/1.4002946 History: Received May 18, 2010; Revised May 27, 2010; Published April 25, 2011; Online April 25, 2011

## Abstract

Due to stringent emission restrictions, modern gas turbines mostly rely on lean premixed combustion. Since this combustion mode is susceptible to thermoacoustic instabilities, there is a need for modeling tools with predictive capabilities. Linear network models are able to predict the occurrence of thermoacoustic instabilities but yield no information on the oscillation amplitude. The prediction of the pulsation levels and hence an estimation whether a certain operating condition has to be avoided is only possible if information on the nonlinear flame response is available. Typically, the flame response shows saturation at high forcing amplitudes. A newly constructed atmospheric test rig, specifically designed for the realization of high excitation amplitudes over a broad frequency range, is used to generate extremely high acoustic forcing power with velocity fluctuations of up to 100% of the mean flow. The test rig consists of a generic combustor with a premixed swirl-stabilized natural gas flame, where the upstream part has a variable length to generate adaptive resonances of the acoustic field. The $OH∗$ chemiluminescence response, with respect to velocity fluctuations at the burner, is measured for various excitation frequencies and amplitudes. From these measurements, an amplitude dependent flame transfer function is obtained. Phase-averaged $OH∗$ pictures are used to identify changes in the flame shape related to saturation mechanisms. For different frequency regimes, different saturation mechanisms are identified.

###### FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

## Figures

Figure 1

Acoustic energy balance

Figure 2

Test rig overview

Figure 3

Burner, left: swirl generator with annular duct and area jump to silica glass combustion chamber; right: cut through the movable block swirl generator

Figure 4

Principle sketch of pressure fluctuation due to flame response to sweep excitation; resonant frequencies are used for monofrequent excitation

Figure 5

Sketch of the combustion chamber and image of the flame

Figure 6

Flame describing function for u′/umean=0.1,0.2,0.3,0.4,0.5, arrow indicates increasing amplitudes

Figure 7

OH∗ response at 128 Hz

Figure 8

OH∗ pictures of the flame at a forcing frequency of 128 Hz: phase-averaged, Abel deconvoluted, for increasing excitation amplitudes

Figure 9

OH∗ chemiluminescence intensity normalized with its mean value; averaged over the non-Abel deconvoluted flame images at 128 Hz for different forcing amplitudes; arrow indicates direction of increasing forcing amplitude

Figure 10

Center of mass movement over one period at a forcing frequency of 128 Hz; arrow indicates direction of increasing forcing amplitude; saturation at four highest amplitudes visible; coordinates related to combustion chamber inlet

Figure 11

Center of mass averaged over one period—each line for one frequency at different excitation amplitudes, starting at the squares

Figure 12

OH∗ response at 292 Hz

Figure 13

OH∗ pictures of the flame at a forcing frequency of 292 Hz: phase-averaged, Abel deconvoluted, for increasing excitation amplitudes

Figure 14

OH∗ chemiluminescence intensity—for each excitation amplitude normalized with its mean value; averaged over the non-Abel deconvoluted flame images at 292 Hz; arrow indicates direction of increasing forcing amplitude

Figure 15

Photomultiplier signal of a self-excited instability at 173 Hz

Figure 16

Normalized OH∗ response at 159 Hz (top), 184 Hz (middle), and 50 Hz (bottom)

## Errata

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 Proceedings 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