On Prediction of Combustion Generated Noise with the Turbulent Heat Release Rate

Author： Zhang F. Habisreuther P. Bockhorn H. Nawroth H. Paschereit C. O.

ISSN： 1610-1928

Source： Acta Acustica united with Acustica, Vol.99, Iss.6, 2013-11, pp. : 940-951

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Abstract

The work aims to develop and to validate hybrid LES/CAA techniques for numerical computation of direct combustion noise exclusively using the unsteady heat release as main source for the CAA modeling. In order to calculate the unsteady heat release, compressible LES has been carried out for a moderately turbulent jet flame employing a combustion model, which is based on tabulation of chemical scalars to include reaction kinetics and modeling the turbulent flame speed to account for flame-turbulence interaction. As the heat release is not explicitly known due to the use of tabulated chemistry, a new method has been introduced first to evaluate this parameter from turbulent combustion modeling. For the CAA simulation, a rearranged Lighthill wave equation has been used, where the source term is essentially built up by the heat release rate and provided by the LES. The sound pressure level derived from the CAA computation showed a reasonable good agreement with the measured microphone data. In addition, with help of the heat release calculated from LES, the analytical solution of the CAA equation has been explored in order to predict noise emissions without solving the corresponding acoustic equation. Applicability of this approach has proved to be promising.