1. Experimental investigation on the effects of a mesh in the downstream region of a combustion-driven Rijke tube on self-excited thermoacoustic oscillations.
- Author
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Liu, Xuanqi, Lai, Yufeng, Fisk, Callum, Willmott, Jon, Zhou, Huaichun, and Zhang, Yang
- Subjects
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SELF-induced vibration , *NONLINEAR oscillations , *STRUCTURAL dynamics , *OSCILLATIONS , *THERMOGRAPHY , *COMBUSTION efficiency - Abstract
• A mesh in downstream region can suppress oscillation by 50% and raise frequency. • Incorporating a mesh leads to more system state variations from recurrence analysis. • Mesh number can affect system behaviours to a larger extent than mesh position. • Degree of mesh temperature fluctuation is related to both mesh number and position. • The mesh acts as a heat and flow disturbance source in the downstream region. Self-excited thermoacoustic oscillations are undesirable in most combustion systems due to their negative influence on combustion efficiency and structural vibration. Nonlinear thermoacoustic oscillations driven by combustion can be sensitive to changes in the heat and flow conditions. Therefore, a comprehensive study on self-excited thermoacoustic oscillations was conducted to investigate the effect of incorporating a woven mesh with varying mesh numbers and positions into the downstream region of a Rijke tube. This study determined system frequency and amplitude response and revealed dynamic properties of the system by applying recurrence analysis. To obtain temperature distributions, a thermal imaging system was employed, comprising a short wavelength infrared (SWIR) camera for the mesh and a long wavelength infrared (LWIR) camera for the tube wall. A high-speed schlieren imaging system was utilised for visualising heat and flow conditions at the tube end. The study demonstrated the effect of including a mesh in changing the oscillation eigenfrequency, suppressing the oscillation amplitude by up to 50 % and influencing the system dynamics. Higher mesh number demonstrated greater effectiveness. The captured thermal and schlieren images clearly evidenced the mesh's significant influence on the downstream heat and flow conditions. The insights gained from this work provide a potential control method of self-excited, nonlinear thermoacoustic oscillations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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