Entropy noise: a review of theory, progress and challenges

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Title: Entropy noise: a review of theory, progress and challenges
Authors: Morgans, AS
Duran, I
Item Type: Journal Article
Abstract: Combustion noise comprises two components: direct combust ion noise and indirect combustion noise. The latter is the lesser studied, with entropy noise believed to be its main co mponent in combusting flows. Entropy noise is generated via a sequence involving diverse flow physics. It has enjoyed a re surgence of interest over recent years, due to its increasin g importance to aero-engine exhaust noise and a recognition t hat it can affect gas turbine combustion instabilities. Entropy noise occurs when unsteady heat release rate genera tes temperature fluctuations (entropy waves), and these subsequently undergo acceleration. Five stages of flow phys ics have been identified as being important, these being (i) generation of entropy waves by unsteady heat release rate; ( ii) advection of entropy waves through the combustor; (iii) acceleration of entropy waves through either a nozzle or bla de row, to generate entropy noise; (iv) passage of entropy noise through a succession of turbine blade rows to appear at the turbine exit and (v) reflection of entropy noise back into the combustor, where it may further perturb the flame, in fluencing the combustor thermoacoustics. This paper reviews the underlying theory, recent progress and outstan ding challenges pertaining to each of these stages
Issue Date: 2-Jun-2016
Date of Acceptance: 13-Jan-2016
ISSN: 1756-8277
Publisher: SAGE Publishing
Start Page: 285
End Page: 298
Journal / Book Title: International Journal of Spray and Combustion Dynamics
Volume: 8
Issue: 4
Copyright Statement: © 2016 The Author(s). Creative Commons CC-BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 License (http://www. which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (
Sponsor/Funder: Commission of the European Communities
Funder's Grant Number: FP7 - 305410
Publication Status: Published
Open Access location:
Appears in Collections:Faculty of Engineering
Mechanical Engineering

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