Demonstration of Active Control of Combustion Instabilities on a Full-Scale Gas Turbine Combustor

Abstract

This paper presents the results of an investigation of active control of combustion instabilities in a natural gas, high-pressure, full-scale gas turbine combustor that was retrofitted with an Active Control System (ACS). The combustor test rig simulates the geometry, inlet airflow distribution, and pressurization of a can-type combustor that exhibits dynamic flame instabilities at some off-design operating conditions. Two essential features of the investigated ACS are 1) a real-time mode observer that identified the frequencies, amplitudes and phases of the dominant modes in the pressure signal and 2) a fast response servo valve that can modulate a large portion of the gaseous fuel. Two active control configurations were studied. In the first configuration, the actuator was mounted on one of two premixed fuel stages, and in the second configuration it was mounted on the inlet to the stabilizing diffusion stage. In both configurations, the ACS damped combustion instabilities, attenuating the dominant mode by up to 15dB and reducing the overall broadband noise by 30-40%. NOx emissions were also reduced by approximately 10% when control was applied. Finally, this study demonstrated the importance of having a fast multiple-mode observer when dealing with complex combustion processes with inherently large time delays.

Dynamics and stability of lean-premixed swirl-stabilized combustion

“…Active instability control on a SiemensWestinghouse dry-low-NO x can-type combustor was reported by Johnson et al [407]. The combustion system consisted of eight main premixing passages dumping into a common flame zone.…”

“…Although numerous active instability control techniques have been developed and applied to laboratory-scale research combustors, only a few full-scale implementations have been reported on gas turbine combustors in the past [48,63,407], and more recently by Richards et al [408]. Practical full-scale implementations present several technological challenges.…”

Adaptive Instability Suppression Controls Method For Aircraft Gas Turbine Engine Combustors

“…Some active control concepts involved speaker actuation [5][6][7][8][9][10][11] and others involved fuel modulation. [12][13][14][15][16] Fuel modulation is more applicable to aircraft gas turbine engines. Several techniques have shown some success in suppressing the frequency spectra of low frequency instabilities, with less success in suppressing the time domain pressure fluctuations.…”

Validation of an Adaptive Combustion Instability Control Method for Gas-Turbine Engines

“…Some active control concepts involved speaker actuation 4,5,6,7,8,9,10 and others involve fuel modulation. 11,12,13,14,15 Fuel modulation is more applicable to aero-type engines. But even the latter techniques have shown limited success in suppressing the frequency spectra of low frequency instabilities, and even less success in suppressing the time domain pressure fluctuations.…”