Acoustic wave propagation in a duct with varying temperatures

Abstract

This project examines the propagation of an acoustic wave through a composite duct. The geometry of the duct is selected to approximate that of a gas turbine combustor and a temperature field is applied to this geometry. The temperature field was obtained from a CFD model of a working gas turbine combustor and the acoustic modelling was performed in the ANSYS Mechanical Acoustic ACT extension, using Finite Element methods. The CFD models were validated by comparing their results with data from the manual for the engine used as the basis for these models. The acoustic models were verified and validated by comparing them with the results of a 1 dimensional, theoretical model implemented in various Matlab scripts. The final model presents the Sound Pressure level in the composite duct with an applied temperature field at a frequency of 600Hz and with an excitation of 1m.The use of the Finite Element approach and the assumptions central to the theoretical model were found to be reasonable for the conditions encountered in the combustor. The Finite Element models showed good agreement with the theoretical models and the next steps in the development of these models were presented.