The Effect of Transient Fuel Staging on Self-Excited Instabilities in a Multi-Nozzle Model Gas Turbine Combustor

Conference · Mon Jun 26 04:00:00 EDT 2017

DOI:https://doi.org/10.1115/GT2017-63479· OSTI ID:1462984

Culler, Wyatt ^[1]; Samarasinghe, Janith; Quay, Bryan; Santavicca, Domenic; O'Connor, Jacqueline

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1. Pennsylvania State University

Combustion instability in gas turbines can be mitigated using active techniques or passive techniques, but passive techniques are almost exclusively used in industrial settings. While fuel staging, a common passive technique, is effective in reducing the amplitude of self-excited instabilities in gas turbine combustors at steady-state conditions, the effect of transients in fuel staging on self-excited instabilities is not well understood. This paper examines the effect of fuel staging transients on a laboratory-scale five-nozzle can combustor undergoing self-excited instabilities. The five nozzles are arranged in a four-around-one configuration and fuel staging is accomplished by increasing the center nozzle equivalence ratio. When the global equivalence ratio is φ = 0.70 and all nozzles are fueled equally, the combustor undergoes self-excited oscillations. These oscillations are suppressed when the center nozzle equivalence ratio is increased to φ = 0.80 or φ = 0.85. Two transient staging schedules are used, resulting in transitions from unstable to stable operation, and vice-versa. It is found that the characteristic instability decay times are dependent on the amount of fuel staging in the center nozzle. It is also found that the decay time constants differ from the growth time constants, indicating hysteresis in stability transition points. High speed CH* chemiluminescence images in combination with dynamic pressure measurements are used to determine the instantaneous phase difference between the heat release rate fluctuation and the combustor pressure fluctuation throughout the combustor. This analysis shows that the instability onset process is different from the instability decay process.

• Research Organization: Pennsylvania State University
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• DOE Contract Number: FE0025495
• OSTI ID: 1462984
• Report Number(s): ISBN: 978-0-7918-5084-8
• Country of Publication: United States
• Language: English

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