Numerical Study of Structural Vibration Induced by Combustion Noise - One Way Interaction

The turbulent flame in the lean combustion regime in a gas turbine combustor generates significant thermo-acoustic noise. The thermo-acoustic noise induces liner vibrations that may lead to fatigue damage of the combustion system. This phenomenon is investigated in the project FLUISTCOM using both an experimental and a numerical approach. The correlation between acoustic pressure oscillations on one side and liner vibrations on the other side is a prime interest. In order to have better insight in the processes present in the combustion chamber, a combustion test rig was designed and manufactured at the University of Twente. One of the most important parts of the test rig is a liner with a flexible section and optical access to measure the vibration pattern and amplitude. This paper describes a flame investigated at 1.5 bar, 125 kW with premixed natural gas and air. The experimental measurements of the vibrations are done with the use of a Laser Doppler Vibrometer. CFX-Ansys was used for the transient numerical calculations of the transient combustion flow within the combustion chamber. Simultaneously, the pressure results from the near-wall region were collected and sent as initial conditions to a structural code (Ansys). Results show the one way response of the liner structure as a result of the transient pressure generated by the combustion of the gas flow. The paper will present the numerically predicted results on the combustion field, the accompanying oscillating pressure field, and the induced structural vibration of the combustor liner. These results will be compared with the available experimental data.