Effect of Perforated Plates on the Acoustics of Annular Combustors

This paper aims to show the influence of perforated plates on the acoustic modes in aeronautical gas turbine combustion chambers. The analytical model was implemented in a three-dimensional acoustic Helmholtz solver to account for the effect of perforated plates. First, an analytic test case is used to validate the coding in the acoustic solver. Then, a computation of the acoustic modes in an actual industrial chamber is conducted, taking into account the perforated liners. For both cases, a study of the influence of the bias flow speed is conducted. The acoustic energy budget is also used to evaluate the respective contributions of the perforated plates. In the case of the industrial chamber, some plates are proved to be more effective than the others, depending on the mode structure.