doi: 10.3850/S201042862015001209

Investigation on Characteristics and Control Strategy for Thermoacoustic
Oscillations in a Rijke Tube

Yajing Yang¹, Xiaoya Li, Wei Xie and Bakhtyar Kakar State Key Laboratory for Strength and Vibration of Mechanical Structures,
School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, China ¹yjyang@mail.xjtu.edu.cn

ABSTRACT

Thermoacoutic instability in modern gas turbines has become a prominent problem. Especially in this study, a two-dimensional numerical simulation and corresponding experiment have been carried on to investigate the occurrence and suppression method for this thermoacoustic phenomenon.
In numerical simulation, the influencing law of heat source position, heat source power and air flow rate on sound intensity and frequency were investigated. Especially, sound intensity reached the maximum when heat source was set at a quarter of Rijke tube length, and unstable region extended with increasing heat source power and air flow rate. Furthermore, a cold-flow pipe with the perforated liner was designed to try to suppress thermoacoustic instability, the numerical results showed that the perforated liner could reduce sound intensity indeed, and the suppression effect was more effective with increasing length of perforated liner. And meanwhile, the corresponding experiment was conducted, and the experimental results were in good agreement with numerical data, which demonstrated the feasibility of two-dimensional simulation model for investigating thermoacoustic instability in Rijke tube. Considering the limitations of perforated liner in practical applications, a bias flow as an active factor was added in numerical simulations. The results revealed that the sound intensity decreased gradually with increasing bypass mass flow, and when the bias flow reached a certain value, the unstable phenomenon would disappear.
The results obtained in this study could provide a useful reference for developing effective inhibiting methods of thermoacoustic instability in a real combustion chamber.

Keywords: Thermoacoutic instability, Numerical simulation, Sound intensity, Perforated liner, Rijke tube.

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