Best Practice Advice AC1-01: Difference between revisions

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{{AC|front=AC 1-01|description=Description_AC1-01|testdata=Test Data_AC1-01|cfdsimulations=CFD Simulations_AC1-01|evaluation=Evaluation_AC1-01|qualityreview=Quality Review_AC1-01|bestpractice=Best Practice Advice_AC1-01|relatedUFRs=Related UFRs_AC1-01}}
='''Aero-acoustic cavity'''=
='''Aero-acoustic cavity'''=


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'''Key Fluid Physics'''
'''Key Fluid Physics'''


[[Image:d34_image002.gif]]  Description of Application Challenge




[[Image:d34_image002.gif]] 




Description of Application Challenge




[[Image:d34_image004.gif]]                   




(Figure dimensions in inches)
(Figure dimensions in inches)


•        
                             
                                                             
• M219 Transonic Cavity
                                 
• M∞ = 0.85


•       M219 Transonic Cavity
• L/D (length/depth ratio) = 5 
                         


•       M∞ = 0.85
                               
• W/D (width/depth ratio) = 1


•       L/D (length/depth ratio) = 5
• ReL = 6.84x106


•        W/D (width/depth ratio) = 1


•        ReL = 6.84x106


[[DOAPs]]
 
DOAPs


On 10 points along cavity ceiling;
On 10 points along cavity ceiling;
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•        Power Spectral Density (PSD) or Sound Pressure Level (SPL)
•        Power Spectral Density (PSD) or Sound Pressure Level (SPL)


Flow Physics
 
'''Flow Physics'''


•        Sharp edge separation
•        Sharp edge separation
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•        Cavity flow recirculation
•        Cavity flow recirculation


•        Shear layer oscillation. The DOAPs are driven by the shear layer oscillation, therefore it is important to resolve this feature well.
•        Shear layer oscillation. The [[DOAPs]] are driven by the shear layer oscillation, therefore it is important to resolve this feature well.


•        Large eddy structures
•        Large eddy structures
Line 69: Line 62:
•        Coherent (vortex shedding) and broadband (turbulent) structures
•        Coherent (vortex shedding) and broadband (turbulent) structures


Underlying Flow Regimes
 
'''Underlying Flow Regimes'''


•        Cavity Flow
•        Cavity Flow
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Neither of these are in the Knowledge Base.
Neither of these are in the Knowledge Base.
© ERCOFTAC 2004
 
Application Uncertainties
 
'''Application Uncertainties'''


•        Upstream turbulence level
•        Upstream turbulence level


•        Boundary layer ahead of cavity leading edge – not known whether the boundary layer is tripped or not.
•        Boundary layer ahead of cavity leading edge – not known whether the boundary layer is                                                                     tripped or not.
© ERCOFTAC 2004
Computational Domain and Boundary Conditions


Computational Domain
 
'''Computational Domain and Boundary Conditions'''
 
'''Computational Domain'''


•        Upstream domain starts at rig sharp leading edge, downstream one cavity length behind cavity trailing edge.
•        Upstream domain starts at rig sharp leading edge, downstream one cavity length behind cavity trailing edge.
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•        Side domains one cavity width away from side edge.
•        Side domains one cavity width away from side edge.


Boundary Conditions
 
'''Boundary Conditions'''


•        M=0.85, T=305.06K on upstream boundary
•        M=0.85, T=305.06K on upstream boundary
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•        No slip conditions on cavity walls, with hybrid low-Re / wall-function
•        No slip conditions on cavity walls, with hybrid low-Re / wall-function
© ERCOFTAC 2004
 
Discretisation and Grid Resolution
 
 
'''Discretisation and Grid Resolution'''


•        Second-order special discretisation (MARS) on momentum
•        Second-order special discretisation (MARS) on momentum
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•        Better than 1st order temporal discretsation
•        Better than 1st order temporal discretsation
© ERCOFTAC 2004
 
Physical Modelling
 
 
'''Physical Modelling'''


•        Transient
•        Transient
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•        Low-Reynolds number k-epsilon (linear and non-liners) turbulence models
•        Low-Reynolds number k-epsilon (linear and non-liners) turbulence models
© ERCOFTAC 2004
 
Recommendations for Future Work
 
 
'''Recommendations for Future Work'''


•        Extension to 3D
•        Extension to 3D
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Both these recommendations have been followed in later studies reported by the Application Challenge Author – see additional reference section below [1,3].
Both these recommendations have been followed in later studies reported by the Application Challenge Author – see additional reference section below [1,3].
© ERCOFTAC 2004
 
Additional References
 
'''Additional References'''


[1] Mendonca, F., Allen, R., de Charentenay, J. and Kirkham, D., “CFD Prediction of narrowband and broadband cavity acoustics at M=0.85”, AIAA-2003-3303, 9th AIAA/CEAS Aeroacoustics Conference and Exhibit, Hilton Head, South Carolina, USA, May 2003.
[1] Mendonca, F., Allen, R., de Charentenay, J. and Kirkham, D., “CFD Prediction of narrowband and broadband cavity acoustics at M=0.85”, AIAA-2003-3303, 9th AIAA/CEAS Aeroacoustics Conference and Exhibit, Hilton Head, South Carolina, USA, May 2003.
Line 132: Line 136:


[3] Allen, R., and Mendonça, F., “DES Validations of Cavity Acoustics over the subsonic to Supersonic Range”, AIAA-2004-2862, 10th AIAA/CEAS Aeroacoustics Conference and Exhibit, Manchester, UK, May 2004
[3] Allen, R., and Mendonça, F., “DES Validations of Cavity Acoustics over the subsonic to Supersonic Range”, AIAA-2004-2862, 10th AIAA/CEAS Aeroacoustics Conference and Exhibit, Manchester, UK, May 2004
© copyright ERCOFTAC 2004
© copyright ERCOFTAC 2004
----


Contributors: Fred Mendonca; Richard Allen - Computational Dynamics Ltd
Contributors: Fred Mendonca; Richard Allen - Computational Dynamics Ltd


Site Design and Implementation: Atkins and UniS
Site Design and Implementation: [[Atkins]] and [[UniS]]
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{{AC|front=AC 1-01|description=Description_AC1-01|testdata=Test Data_AC1-01|cfdsimulations=CFD Simulations_AC1-01|evaluation=Evaluation_AC1-01|qualityreview=Quality Review_AC1-01|bestpractice=Best Practice Advice_AC1-01|relatedUFRs=Related UFRs_AC1-01}}

Latest revision as of 14:42, 11 February 2017

Front Page

Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice

Aero-acoustic cavity

Application Challenge 1-01 © copyright ERCOFTAC 2004


Best Practice Advice for the AC

Key Fluid Physics


D34 image002.gif


Description of Application Challenge


D34 image004.gif


(Figure dimensions in inches)


• M219 Transonic Cavity

• M∞ = 0.85

• L/D (length/depth ratio) = 5


• W/D (width/depth ratio) = 1

• ReL = 6.84x106



DOAPs

On 10 points along cavity ceiling;

• RMS pressures

• Power Spectral Density (PSD) or Sound Pressure Level (SPL)


Flow Physics

• Sharp edge separation

• Cavity flow recirculation

• Shear layer oscillation. The DOAPs are driven by the shear layer oscillation, therefore it is important to resolve this feature well.

• Large eddy structures

• Coherent (vortex shedding) and broadband (turbulent) structures


Underlying Flow Regimes

• Cavity Flow

• 2D Unsteady Shear Layer

Neither of these are in the Knowledge Base.


Application Uncertainties

• Upstream turbulence level

• Boundary layer ahead of cavity leading edge – not known whether the boundary layer is tripped or not.


Computational Domain and Boundary Conditions

Computational Domain

• Upstream domain starts at rig sharp leading edge, downstream one cavity length behind cavity trailing edge.

• Side domains one cavity width away from side edge.


Boundary Conditions

• M=0.85, T=305.06K on upstream boundary

• Side boundaries, top boundary and downstream boundary, constant pressure = 62059.14Pa

• No slip conditions on cavity walls, with hybrid low-Re / wall-function


Discretisation and Grid Resolution

• Second-order special discretisation (MARS) on momentum

• Hexahedral orthogonal meshes with successive 2x2 refinement into the shear layer and walls are necessary. Mesh dependency analysis shows low sensitivity to refiments greater than 40000 cells in the 2D plane.

• Better than 1st order temporal discretsation


Physical Modelling

• Transient

• Compressible ideal gas

• Low-Reynolds number k-epsilon (linear and non-liners) turbulence models


Recommendations for Future Work

• Extension to 3D

• LES-based turbulence modeling

• Full second-order central differencing special discretisation in the LES flow regions

Both these recommendations have been followed in later studies reported by the Application Challenge Author – see additional reference section below [1,3].


Additional References

[1] Mendonca, F., Allen, R., de Charentenay, J. and Kirkham, D., “CFD Prediction of narrowband and broadband cavity acoustics at M=0.85”, AIAA-2003-3303, 9th AIAA/CEAS Aeroacoustics Conference and Exhibit, Hilton Head, South Carolina, USA, May 2003.

[2] Allen, R., and Mendonça, F., “DES Predictions on the M219 cavity at M=0.85”, Colloquium EUROMECH 449, Chamonix, France, 7-8th December 2003

[3] Allen, R., and Mendonça, F., “DES Validations of Cavity Acoustics over the subsonic to Supersonic Range”, AIAA-2004-2862, 10th AIAA/CEAS Aeroacoustics Conference and Exhibit, Manchester, UK, May 2004

© copyright ERCOFTAC 2004



Contributors: Fred Mendonca; Richard Allen - Computational Dynamics Ltd

Site Design and Implementation: Atkins and UniS


Front Page

Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice

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