Entropy noise: a review of theory, progress and challenges
File(s)
Published version
Author(s)
Morgans, AS
Duran, I
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
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
Date Issued
2016-06-02
Date Acceptance
2016-01-13
Citation
International Journal of Spray and Combustion Dynamics, 2016, 8 (4), pp.285-298
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. creativecommons.org/licenses/by-nc/3.0/) 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 (https://us.sagepub.com/en-us/nam/open-access-at-sage).
Sponsor
Commission of the European Communities
Grant Number
FP7 - 305410
Publication Status
Published