Imperial College London
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Professor Aimee S. Morgans

Faculty of Engineering, Department of Mechanical Engineering

Professor of Thermofluids
 
 
 
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Contact

 

+44 (0)20 7594 9975a.morgans

 
 
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Location

 

621City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Li:2018:10.1177/1756827717743910,
author = {Li, J and Yang, D and Morgans, A},
doi = {10.1177/1756827717743910},
journal = {International Journal of Spray and Combustion Dynamics},
pages = {131--153},
title = {The effect of an axial mean temperature gradient on communication between one-dimensional acoustic and entropy waves},
url = {http://dx.doi.org/10.1177/1756827717743910},
volume = {10},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This work performs a theoretical and numerical analysis of the communication between one-dimensional acoustic and entropy waves in a duct with a mean temperature gradient. Such a situation is highly relevant to combustor flows where the mean temperature drops axially due to heat losses. A duct containing a compact heating element followed by an axial temperature gradient and choked end is considered. The proposed jump conditions linking acoustic and entropy waves on either side of the flame show that the generated entropy wave is generally proportional to the mean temperature ratio across the flame and the ratio (F-1), where F is the flame transfer function. It is inversely proportional to the Mach number immediately downstream of the flame M2. The acoustic and entropy fields in the region of axial mean temperature gradient are calculated using four approaches: (1) using the full three linearised Euler equations as the reference; (2) using two linearised Euler equations in which the acoustic and entropy waves are assumed independent (thus allowing the extent of communication between the acoustic and entropy wave to be evaluated); (3) using a Helmholtz solver which neglects mean flow effects and (4) using a recently developed analytical solution. It is found that the communication between the acoustic and entropy waves is small at low Mach numbers; it rises with increasing Mach number and cannot be neglected when the mean Mach number downstream of the heating element exceeds 0.1. Predictions from the analytical method generally match those from the full three linearised Euler equations, and the Helmholtz solver accurately determines the acoustic field when M2≤0.1.
AU  - Li,J
AU  - Yang,D
AU  - Morgans,A
DO  - 10.1177/1756827717743910
EP  - 153
PY  - 2018///
SN  - 1756-8277
SP  - 131
TI  - The effect of an axial mean temperature gradient on communication between one-dimensional acoustic and entropy waves
T2  - International Journal of Spray and Combustion Dynamics
UR  - http://dx.doi.org/10.1177/1756827717743910
UR  - http://hdl.handle.net/10044/1/54422
VL  - 10
ER  -
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