Investigation of combustion noise using a LES/CAA hybrid approach

A hybrid approach combining large eddy simulation with computational aeroacoustics (LES/CAA) to describe combustion noise in the near field of a turbulent flame is presented. The approach is based on a LES of the reactive flow field using a low Mach number approximation and the solution of the wave equation with the appropriate combustion noise source term and inhomogeneous fluid properties. Two well established solvers are combined into a single tool for the description of the acoustics in the vicinity of the flame, exploiting the disparity of scales between the fluid flow and the acoustics. The complete approach is tested for a non-premixed turbulent jet flame and provides an insight into the combustion noise phenomenon. The LES is shown to yield good agreement with measurements for the velocity, the mixture fraction, as well as the temperature. The comparison of the acoustic results to an experimentally determined noise intensity spectrum allows to judge on the prediction quality of the presented LES/CAA hybrid approach. (c) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.