Master's Thesis Proposal

Leo Kastenberg

(Advisor: Prof. Suresh Menon)

Combustion Noise Modeling Using Large Eddy Simulation

Wednesday, March 5

4:30 p.m.

Montgomery Knight Building 317

Abstract

Aircraft noise pollution is detrimental to human well-being in the vicinity of airports. Historically, the main sources of combustion noise have been fan, compressor, combustor, turbine, and jet noise. Advances such as improvements in blade geometry, acoustic liners, and the advent of high-bypass turbofans have reduced noise from non-combustion sources. Now, combustion noise is one of the major contributors to engine noise, and it will need to be addressed in order to significantly reduce aircraft noise pollution. Combustion noise can be divided into two types: direct and indirect noise. Direct noise is produced when unsteady heat release rate in the flame creates fluctuations in pressure which are then convected downstream. Indirect noise is produced when fluctuations in entropy, vorticity, and composition are convected downstream and accelerated through either a nozzle or turbine. Although vortical and compositional inhomogeneities have been shown to produce indirect noise, entropy fluctuations are the main source. This thesis proposes the use of Large Eddy Simulation (LES) to analyze the production of direct and indirect noise in a Rich-Quench-Lean (RQL) combustor. Once the baseline case has been performed and verified against experimental data, another LES will be performed using a modified setup containing a variable length resonator tube attached between the combustor and nozzle, which will be used to excite modes in the combustor. Analysis on both cases will be performed to determine the effect of the excited modes on the processes which produce combustion noise, such as dynamic flame structures.

· Prof. Suresh Menon – School of Aerospace Engineering (advisor)

· Prof. Vigor Yang– School of Aerospace Engineering

· Dr. Vishal Acharya– School of Aerospace Engineering