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Title: The effect of variable fuel staging transients on self-excited instabilities in a multiple-nozzle combustor

Journal Article · · Combustion and Flame
 [1];  [1];  [1];  [1];  [1]; ORCiD logo [1]
  1. Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering
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Combustion instability in gas turbine engines is often mitigated using fuel staging. Fuel staging, sometimes referred to as fuel splitting, is a strategy by which fuel is unevenly distributed between different nozzles of a multiple-nozzle combustor. These fuel splits are conducted in a transient manner in real engines, and the effects of these transients on instability are not well characterized. This work fills this gap by systematically studying the effects of transient fuel staging on self-excited combustion instability by varying the amount of staging fuel (staging amplitude), timescale in which the fuel is added (transient duration), and whether staging fuel is added or subtracted (transient direction). In this work, three staging amplitudes, five transient durations, and both transient directions are considered. The transient timescales are broadly divided into “short” duration transients, which have fuel delivery timescales shorter than the characteristic instability decay or onset timescales, and “long” duration transients, which have fuel delivery timescales longer than the characteristic instability decay or onset timescales. For short duration transients, we find the instability decay timescale depends on staging amplitude but does not depend on transient duration. For long duration transients, we find the instability decay timescale does not strongly depend on staging amplitude. The instability onset timescale is found to be longer and more variable between runs than the instability decay timescale for a given fuel delivery timescale. The onset timescale is also longer in duration and more variable than the decay timescale at a given fuel delivery timescale, implying that the instability rise process is overall more variable and slower than the instability decay process. Analysis of combustor damping rates show a strong dependence of damping rate on staging amplitude but no strong dependence on transient duration or direction. Instantaneous phase difference images between p' and are used to differentiate regions in the combustor that have constructive versus destructive interference between heat release rate oscillations and pressure fluctuations. Furthermore, the phase images show that p' and q.' become in-phase early in the transient for the onset transients.

Research Organization:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Organization:
USDOE Office of Fossil Energy (FE)
Grant/Contract Number:
FE0025495
OSTI ID:
1462982
Alternate ID(s):
OSTI ID: 1582852
Journal Information:
Combustion and Flame, Vol. 194, Issue C; ISSN 0010-2180
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 19 works
Citation information provided by
Web of Science

References (17)

The Effect of Fuel Staging on the Structure and Instability Characteristics of Swirl-Stabilized Flames in a Lean Premixed Multinozzle Can Combustor journal August 2017
Effect of Azimuthally Nonuniform Heat Release on Longitudinal Combustion Instabilities journal January 2017
Measurements of triggering and transient growth in a model lean-premixed gas turbine combustor journal March 2012
Bifurcations of Self-Excited Ducted Laminar Premixed Flames journal December 2011
Dynamic properties of combustion instability in a lean premixed gas-turbine combustor journal March 2011
Comparison of Linear Stability Analysis With Experiments by Actively Tuning the Acoustic Boundary Conditions of a Premixed Combustor
  • Bothien, Mirko R.; Moeck, Jonas P.; Paschereit, Christian Oliver
  • Journal of Engineering for Gas Turbines and Power, Vol. 132, Issue 12 https://doi.org/10.1115/1.4000806
journal August 2010
A method to identify thermoacoustic growth rates in combustion chambers from dynamic pressure time series journal January 2017
Non-stationary local thermoacoustic phase relationships in a gas turbine combustor journal January 2017
Intermittency as a Transition State in Combustor Dynamics: An Explanation for Flame Dynamics Near Lean Blowout journal June 2015
Forced Response of a Swirling, Premixed Flame to Flow Disturbances journal September 2006
The Three-Dimensional Structure of Swirl-Stabilized Flames in a Lean Premixed Multinozzle Can Combustor journal September 2015
Experimental Diagnostics for the Study of Combustion Instabilities in Lean Premixed Combustors journal September 2003
Experimental Investigation of Limit-Cycle Oscillations in an Unstable Gas Turbine Combustor journal January 2002
Online Combustor Stability Margin Assessment Using Dynamic Pressure Data journal June 2005
On the experimental determination of growth and damping rates for combustion instabilities journal July 2016
Linear Growth Rate Estimation From Dynamics and Statistics of Acoustic Signal Envelope in Turbulent Combustors journal October 2016
Three-Dimensional Chemiluminescence Imaging of Unforced and Forced Swirl-Stabilized Flames in a Lean Premixed Multi-Nozzle Can Combustor journal September 2013

Cited By (2)

Bifurcation dodge: avoidance of a thermoacoustic instability under transient operation journal February 2019
Bifurcation Dodge: Avoidance of a Thermoacoustic Instability under Transient Operation conference January 2019

Figures / Tables (20)

Table 1(p. 9)table Table 1
Table 2(p. 13)table Table 2
Figure 1(p. 42)figure Figure 1
Figure 2(p. 43)figure Figure 2
Figure 3(p. 44)figure Figure 3
Figure 4(p. 45)figure Figure 4
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Figure 13(p. 54)figure Figure 13
Figure 14(p. 55)figure Figure 14
Figure 15(p. 56)figure Figure 15
Figure 16(p. 57)figure Figure 16
Figure 17(p. 58)figure Figure 17
Figure 18(p. 59)figure Figure 18

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