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{Guzman:2021:10.1017/jfm.2021.569,
author = {Guzman, Inigo J and Duran, I and Morgans, AS},
doi = {10.1017/jfm.2021.569},
journal = {Journal of Fluid Mechanics},
pages = {1--38},
title = {Scattering of entropy waves into sound by isolated aerofoils},
url = {http://dx.doi.org/10.1017/jfm.2021.569},
volume = {923},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This article presents a modelling approach to predict the low-frequency sound generated by entropy fluctuations interacting with isolated aerofoils. A model of the acoustic field is obtained based on a linearisation of the compressible Euler equations about a steady, potential, compressible mean flow. Mean flow variations of velocity and density are accounted for in the source term, but are neglected in the sound propagation. Using a Lorentz-type transformation, the problem is reduced to solving a Helmholtz equation. This equation is recast in integral form and a solution is obtained using a compact Green's function method. This approach places no restrictions on the entropy wavelength, while assuming that the acoustic wavelength is large compared to the profile chord and spacing. The source term is further simplified by assuming that the steady flow is a small perturbation to a uniform flow. The model is illustrated using a symmetric aerofoil and its performance is assessed against numerical simulations of the compressible Euler equations. Good agreement is found for all the frequencies of validity of the theory and for all the range of subsonic Mach numbers. The solution for a symmetric aerofoil interacting with plane entropy waves corresponds to the combination of a dipole along the horizontal axis and a monopole. The dipole originates from the unsteady drag experienced by the aerofoil owing to the fluctuations of density and the monopole from the strong local acceleration of the flow at the leading edge. The monopole term becomes negligible for low Mach numbers.
AU  - Guzman,Inigo J
AU  - Duran,I
AU  - Morgans,AS
DO  - 10.1017/jfm.2021.569
EP  - 38
PY  - 2021///
SN  - 0022-1120
SP  - 1
TI  - Scattering of entropy waves into sound by isolated aerofoils
T2  - Journal of Fluid Mechanics
UR  - http://dx.doi.org/10.1017/jfm.2021.569
UR  - https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/scattering-of-entropy-waves-into-sound-by-isolated-aerofoils/169CE955EE4662700F7BE9FEE652FAA2
UR  - http://hdl.handle.net/10044/1/90760
VL  - 923
ER  -
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