The effect of inlet boundaries on combustion instability in a pressure-elevated combustor

Han, Xiao; Yang, Dong; Wang, Jianchen; Zhang, Chi

doi:10.1016/j.ast.2021.106517

Cited by 18 publications

(4 citation statements)

References 33 publications

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“…The droplet diameter and cooling air heavily dominate the oscillation amplitudes of spray flames. Han et al 12 experimentally evaluated the effect of inlet boundaries on combustion instabilities in a spray combustor. They found that the impact of the length of the diffuser on the combustion instability is more pronounced than that of the cross-sectional area of the diffuser.…”

Section: Introductionmentioning

confidence: 99%

Assessing the effects of pressure variations on combustion dynamics in vortex-tube flows

Ren,

Tian,

Jones

2024

Physics of Fluids

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In our investigation, we scrutinize combustion stability in vortex-tube combustion at high operating pressures by examining stability limits, flame configurations, and pressure oscillations. Our examination deeply probes the intricacies of flow and flame behaviors in terms of aerodynamic, thermodynamic, and flamedynamic aspects to identify the fundamental reasons behind stability variances at different pressure levels. The findings indicate that combustion instability escalates with rising operating pressures, marked by increased variability in flame patterns and a monotonic upsurge in pressure oscillation amplitudes. Although aerodynamic and thermodynamic stabilities remain unaffected, the thermoacoustic stability is compromised at elevated pressures. This is evidenced by the strong link between the Rayleigh criterion and the amplitude of pressure fluctuations, with an increased “gain” in the flame transfer function as pressure mounts. The core of the observed thermoacoustic instability is traced back to heightened density variations and mean flow velocities at high pressures, leading to amplified momentum flux oscillations.

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Section: Introductionmentioning

confidence: 99%

Assessing the effects of pressure variations on combustion dynamics in vortex-tube flows

Ren,

Tian,

Jones

2024

Physics of Fluids

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“…With increasingly stringent environmental regulations, most manufacturers have gradually applied advanced lowemission technologies to aero engines and gas turbines (GT) for reducing emissions. 1,2 As one of the most effective technologies, lean premixed combustion technology is widely used in new generation combustor design. [3][4][5][6][7] However, lean premixed combustion is often accompanied by combustion instability.…”

Section: Introductionmentioning

confidence: 99%

Investigation on flame dynamic characteristics to air-inlet excitation in a gas turbine model combustor

Zhang

Liu

Zheng

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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The combustion characteristics for a gas turbine (GT) model combustor in air-inlet excitation are studied by Large Eddy Simulation (LES). Time series of heat release rate (HRR) fluctuation is captured during simulation. The precessing vortex core (PVC) structure is shown by pressure iso-surface, and the single/double helix branches of PVC alternately evolve in one forcing cycle. With the rotation of PVC, the high-speed ring zone (HSRZ) is periodically squeezed, and large-scale vortex roll-up results from that. The flame root structure is also significantly affected by PVC, which is one of the reasons for the HRR fluctuation. With the increase of the forcing amplitude, the flame response is divided into three parts. The linear growth zone and secondary rising zone are separated by saturation plateau. The flame dynamics analysis shows that the change of the flame structures and flame front oscillation modes are the apparent mechanism of the nonlinear flame response appearance.

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“…Because at the upstream position, there are boundary conditions, 39 inlet thermodynamic properties, 40 flow fluctuations, 41 unstable fuel/air mixing, and equivalence ratio oscillation 42–44 . Thermoacoustic will become more frequent, and pollutant emissions will be out of balance 45–47 .…”

Section: Introductionmentioning

confidence: 99%

Suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets

Zhou

2022

Asia-Pacific J Chem Eng

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Passive control methods are widely used in unsteady combustion systems due to their robustness and convenience. This paper used the upstream microjets method for the first time to control thermoacoustic instability and pollutant NOx emissions in unsteady swirl premixed flame. Three variables of CO 2 microjets flow rate, upstream microjets distance, and microjets number are investigated. Results demonstrate the upstream microjets distance plays a significant role in restraining the thermoacoustic instability and NOx emissions. The smaller the upstream microjets distance, the more completely the thermoacoustic instability is suppressed while the NOx emissions are the opposite, which means a compromise choice needs to be made between them. The damping ratio of pressure amplitude in the chamber can reach the maximum of 81.3%, and the damping ratio of CH* intensity can reach the maximum of 80.2%. Besides, the frequency of pressure and CH* will transit to a lower mode. NOx emissions can realize a maximum reduction of 12.2 ppm. Meanwhile, the flame mode switches from an enlarged Mode-A flame to a shrunk Mode-B flame, and the flame length shows a maximum reduction of 14 mm at the largest upstream distance. However, the specific control mechanism under upstream microjets still needs further study to clarify. This research proved the feasibility of suppressing combustion instability and NOx emissions with upstream microjets in unsteady swirl premixed flame, promoting its practical application in gas turbine systems.flame mode, NO x emissions, thermoacoustic instability, unsteady swirl premixed flame, upstream microjets | INTRODUCTIONAs a complex multidisciplinary problem, combustion instability was first proposed by scholar Rayleigh. 1 When combustion instability occurs, it is often accompanied by periodic large pressure oscillations. 2,3 The power engines in gas turbines, industrial furnaces, and rockets will face the threat of damage or even failure.To prevent the occurrence of combustion instability, researchers often implement control strategies from the two necessary factors of combustion instability, namely, acoustic oscillations and heat release oscillations. For

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The effect of inlet boundaries on combustion instability in a pressure-elevated combustor

Cited by 18 publications

References 33 publications

Assessing the effects of pressure variations on combustion dynamics in vortex-tube flows

Assessing the effects of pressure variations on combustion dynamics in vortex-tube flows

Investigation on flame dynamic characteristics to air-inlet excitation in a gas turbine model combustor

Suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets

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