Investigation of combustion noise generated by an open lean-premixed H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si48.svg"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>/air low-swirl flame using the hybrid LES/APE-RF framework

An open lean-premixed hydrogen/air low-swirl (LPHALS) turbulent flame exhibiting a pronounced peak in its combustion noise spectra, is investigated numerically using hybrid Computational Fluid Dynamics/Computational Aero-Acoustics (CFD/CAA) framework. Under this framework, the reacting flow-field of computed via Large-Eddy Simulation (LES), while direct it produces captured by solving Acoustic Perturbation Equations for Reacting Flows (APE-RF). Flame configuration and simulation conditions correspond to those an experimental study on H2/air stabilized Low-Swirl Burner (LSB). LES results are validated against data. The CAA able predict sharp similar one two characteristic peaks observed measured spectra. Frequency spectral predicted 840 Hz, which close that higher frequency secondary at 940 Hz experiment. Upon examining LES/APE-RF results, generation mechanism found be intense local heat release rate fluctuations, caused strong interaction between periodically generated vortical flow structures shear layers, downstream LSB exit. Additionally, analysis content directivity different acoustic source terms performed, order investigate their impact radiated field, hence characteristics produced LPHALS flame.