Large eddy simulation of combustion noise in a realistic gas turbine combustor

Abstract

Combustion noise and engine core noise still remain primary sources of aircraft noise. For their reduction, understanding their generation is crucial. The engine core noise can be divided into direct and indirect noise depending on the source. The direct noise is generated due to the volumetric disturbances created by turbulent combustion, and the indirect noise is generated when the combustion-generated entropic disturbances accelerate or decelerate through the later part of the combustion chamber, i.e., nozzle, turbine, etc. To understand the nature of both direct and indirect noise generation in a realistic gas turbine combustor, a reactive large eddy simulation is conducted in this work. The simulations model liquid spray injection, dispersion, vaporization, combustion, mixing with the cooling jets, and flow acceleration through a downstream nozzle, all in a fully coupled compressible manner. The flame stabilization mechanism, interactions with cooling jets, and acceleration in the nozzle are discussed. The next objective is to identify the corresponding sources of direct and indirect noise generation. Two chamber pressures are simulated for a comparison. Even though the overall combustion characteristics are similar between the two, the pressure signatures show minor differences.