A laboratory scale, swirl stabilized burner is investigated in view of the impact of global equivalence ratio and thermal power variation on broadband combustion noise emission. The PRECCINSTA burner (Prediction and Control of Combustion Instabilities in Industrial Gas Turbines) is operated at atmospheric conditions. The presented combustion noise studies are based on a perfectly premixed configuration, where methane is burnt with air. From experiments, newly measured sound pressure spectra in the combustion system with well-defined acoustic boundary conditions are presented for several thermal loads and global equivalent ratios. For the combustion noise simulations, the hybrid CFD/CCA approach 3D FRPM-CN (Fast Random Particle Method for Combustion Noise Prediction) is used. Numerical simulation results of CFD and combustion acoustics are compared with experimental data in terms of flow field and combustion. 3D FRPM-CN is then assessed for its prediction capability of effects of combustion parameter variation on broadband noise emission. Numerical results are interpreted with a method for spectral mode decomposition. High frequency acoustic modes in the combustion chamber are identified and characterized. Sound pressure spectra from numerical simulations are evaluated with experimental data in view of reproduction of absolute direct combustion noise levels and shape of spectra. With the study presented in this work, not only a combustion noise prediction tools is further validated, but also a large experimental data base for combustion noise and thermo-acoustics validation in swirl-stabilized, confined configurations is introduced.
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