bianchinicosimo phd dissertation 13 april 2011
TRANSCRIPT
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University of FlorenceDepartment of Energy Engineering
Assessment of boundary conditions for heat transfer and
aeroacoustic analysis
Cosimo BianchiniHTC group
Energy Engineering Department
Via di S.Marta 3, 50139 Firenze
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Outline• Introduction
• Generic grid interface for conjugate heat transfer analysis
• Overall effectiveness of effusion cooling plates
• Auto-recycling turbulent inlet condition
• Heat transfer of axisymmetric impingement jet
• Navier-Stokes Characteristic Boundary Conditions
• Acoustic response of perforated plates
• Conclusions
2/17
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Motivation
3/17
Dome cooling
Impingement arrays
Liner cooling
Effusion systems
• Stricter requirements for aero-engine pollutant emission
• Lean Partially Premixed technology
• Reduced amount of air for cooling purposes
• Decreased stability of flames working close to the lean limit
• Perforated plates may absorb acoustic fluctuations
• Present-day aero-engines combustion chambers cooling is obtained by:
• Effusion for the liner
• Impingement in the dome
• Exploit cooling system as passive dampers
• Dual thermal acoustic optimization
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Motivation
4/17
• Numerical predictions to reliably help designers needs to
• overcome known failures of standard CFD analysis
• at a computationally affordable level
• Implement methods for
• Conjugate Heat Transfer analysis
• Large Eddy Simulation
• In the context of open-source CFD
• OpenFOAM®
• Increased complexity require adequate boundary treatment
• Energy balance on the interface needs to be respected
• Grid scale turbulence needs to be specified
DNS
Wall resolved
LES
Far field
LES
Advanced
RANS
RANS
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Objectives
5/17
• The aim of the thesis is to • implement, validate and assess boundary conditions for the study of heat transfer
and aero-acoustic phenomena connected with combustor cooling
• Technological problems faced• Estimate combined effect of film protection and heat sink in effusion cooling devices
• Evaluate the cooling capabilities of impingement jets
• Assess the potential of perforated liners as acoustic dampers for the stabilization of lean flames
• Computational aspects• Conjugate interface boundary condition to couple fluid and solid domain
• Generation of turbulent fluctuations for inflow boundary
• Non-reflecting inflow and outflow boundaries with acoustic forcing
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Conjugate interface• Energy equation solved in terms of temperature (static or total)
• Fluid: convective-diffusive equation • Solid: Fourier equation
• Coupled boundary guarantees• Continuity of temperature• Continuity of heat flux: temperature gradient
• Different mesh requirements for fluid and solid side• No boundary layer in solid domain• Strictly apply only to Low-Reynolds computations• Non conformal interface treatment
6/17
same matrix for solid and fluid domain
fwsw TT ,,
fwf
sws n
Tk
n
Tk
,,
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Effusion cooling conjugate analysis
7/17
• Conventional (circular hole) and shaped (circular imprint) holes
• Same porosity, same slanted angle:17°
• High temperature rig (Poiters): heat shield, 17-12 rows
• 3.5 millions cells hybrid mesh for 8 rows
• Steady-state RANS analysis: Two-Layer (TL) and anisotropic Two-Layer (ATL) turbulence models
ConventionalShaped
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Turbulent inlet
8/17
• Perfect turbulent inlet should:• “look” like turbulence• allow easy specification of turbulent
integral properties• easily adjust to new inlet conditions• be computationally cheap
• Internal mapping• identify an internal portion of
the domain to apply recycling methods
• Feedback• scaling the mapped field to
satisfy specified integral values• Mapped fluctuation
• same procedure applied to fluctuations
• superposed on desired base profiles
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Axisymmetric Impingement Jet
9/17
• Ercoftac database: Re= 23000, H/D=2
• Detailed experimental data
• hexahedral mesh, 84 blocks, 5.2 millions cells
• Incompressible Large Eddy Simulation
• Additional equation for temperature
• One equation sgs model: transport equation for turbulent kinetic energy
• Convective condition on outlet and top boundaries
• Fully developed inlet condition
• Mapped and Mapped fluctuation (from pipe simulation)
0
n
UC
t
U
MappedMapped fluctuation
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Axisymmetric Impingement Jet
10/17
• Mean velocity
• Impinging zone
• Wall jet zone
R/D = 0 R/D = 0.5
R/D = 1 R/D = 2 R/D = 3
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Axisymmetric Impingement Jet
11/17
• Effective fluctuations
• Radial fluctuations
• Axial fluctuations
''rrUU
R/D = 0.5 R/D = 1 R/D = 2 R/D = 3
''zzUU
R/D = 3R/D = 2.5R/D = 1R/D = 0.5
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Axisymmetric Impingement Jet
12/17
• Constant and uniform heat flux: mean Nusselt number
• Controversy on stagnation point dip and secondary peak
• Secondary peak due to periodical impingement of broken ring vortex
• Too low axial fluctuations might have lowered Nu for r/D > 1.5
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Non reflecting boundaries
13/17
• Navier Stokes Characteristic Boundary Conditions (NSCBC)
• Characteristic wave analysis on the boundary
• NSE are rewritten on the boundary in terms of wave amplitude variations
• Entering waves: imposed by means of Linear Relaxation Method
• Outgoing waves: extrapolation from internal solution
• NSE are integrated on the boundary
• Introduction of transverse and diffusive terms
• The reflectivity of the boundary is driven by
• Acoustic forcing is introduced with variable target value
c,,,n
p,n
ufL
)( TL
L
)cos( tAT
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Acoustic response of perforated plates Bellucci test
14/17
• Periodic circular hole at 90 deg with bias flow
• Pulsed pressure outflow and fully reflecting inlet with NSCBC
• Wall Adaptive Local Eddy (WALE) viscosity model
• Estimate reflection coefficient of perforated plate with bias flow
• Multimicrophone (4 stations) post processing technique
• Reconstruction of progressive and regressive wave
R
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Acoustic response of perforated plates Bellucci test
15/17
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Acoustic response of perforated plates KIAI test
16/17
• Same set up more realistic geometry and flow conditions
• Multifrequency excitation
• Effect of stagger studied with different cyclic boundary arrangement at 1000 Hz
i
iiT tAp )cos(
in line staggered rhomboidal staggered rectangular
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Conclusions
17/17
• Three boundary conditions were implemented in an open-source CFD code
• A conjugate interface with implicit non-conformal coupling
• An internal mapping turbulent inlet generator
• Non and partially reflecting inflow and outflow conditions
• Accuracy of prediction was tested under conditions relevant for combustor liners cooling system design
• An effusion cooling plate at engine like condition
• An axisymmetric impingement jet with heat transfer
• The acoustic response of perforated liners with bias flow
• The implemented conditions showed results aligned with “state of the art” computations
• Further work should be addressed towards:
• Improving efficiency, robustness and stability
• Development of homogeneous model for thermal and acoustic behavior of perforated plates
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
Publications• Bianchini, Da Soghe, Facchini, Innocenti, Micio, Bozzi, Traverso, “Development of numerical tools for stator-rotor
cavities calculation in heavy-duty gas turbines", 2008, ASME PAPER GT2008-51266, Asme Turbo Expo, Berlin
• Bianchini, Facchini, Mangani, “Conjugate heat transfer analysis of an internally cooled turbine blades with an object oriented cfd code", 2009, European Turbomachinery Congress, Graz
• Andreini, Bianchini, Ceccherini, Facchini, Mangani, Cinque, Colantuoni, “Investigation of circular and shaped effusion cooling arrays for combustor liner application – Part II: Numerical analysis", 2009, ASME PAPER GT2009-60038, Asme Turbo Expo, Orlando
• Boust, Lalizel, Bianchini, Facchini, Cinque, Colantuoni, “Dual investigations on the improvement of effusion cooling by shaped holes", 2009, 7th World Conference on Experimental Heat transfer Fluid mechanics Thermodynamics, Krakow
• Bianchini, Simonetti, Zecchi, “Numerical and experimental investigation of turning flow effects on innovative pin fin arrangements for trailing edge cooling configurations”, 2010, ASME PAPER GT2010-23536, Asme Turbo Expo, Glasgow to appear on Journal of Turbomachinery
• Bianchini, Mangani, Maritano, “Heat transfer performance of fan-shaped film cooling holes. Part II – Numerical analysis”, 2010, ASME PAPER GT2010-22809, Asme Turbo Expo, Glasgow
• Bianchini, Bonanni, Carcasci, Facchini, Tarchi, “Experimental survey on heat transfer in an internal channel of a trailing edge cooling system”, 2010, 65° ATI conference
• Bianchini, Andreini, Facchini, “Numerical analysis of the heat transfer in a trailing edge cooling duct in stationary and rotating conditions”, 2011,9th European Turbomachinery Congress, Istanbul
• Andreini, Bianchini, Armellini, Casarsa, “Flow field analysis of a trailing edge internal cooling channel”, 2011, ASME PAPER GT2011-45724, Asme Turbo Expo, Vancouver, Accepted for publication
• Simonetti, Andreini, Bianchini, “Assessment of numerical tools for the evaluation of the acoustic impedance of multi-perforated plates”, 2011, ASME PAPER GT2011- 46303, Asme Turbo Expo, Vancouver, Accepted for publication
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University of FlorenceDepartment of Energy Engineering
Assessment of boundary conditions for heat transfer and
aeroacoustic analysis
Cosimo BianchiniHTC group
Energy Engineering Department
Via di S.Marta 3, 50139 Firenze
![Page 20: BianchiniCosimo PhD dissertation 13 April 2011](https://reader034.vdocuments.site/reader034/viewer/2022051515/5533ab584a79594d6f8b48b2/html5/thumbnails/20.jpg)
University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
• Multiple implicit coupling - ghost cell mechanism
• Contribution of ghost cell calculated via cell-to-cell addressing and weighting factors αi
• Weighting factors based on face overlapping areas
• Algorithm for overlapping area based on surface integral of the product of the winding number of the two polygons
• Applies to every non self-intersecting polygon, positively oriented: all types of meshes can be used (tetra,hexa,poly,etc..)
,1f p p p i n ii
w w
,i o i fpA A
,n i n iC C
Domain 1
Domain 2 p
n1 n2
Non conformal interface
Generic grid interface
20/20
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University of FlorenceDepartment of Energy Engineering
Cosimo Bianchini – PhD thesis dissertation – 13/04/2011
DNS – near wall LES – far field LES – Advanced RANS – RANS
Effusion cooling – Effusion acoustic – Impingement jet
KIAI test – Flow field analysis
21/20
• Instantaneous axial velocity show typical turbulent behaviour
• Modal analysis performed with Proper Orthogonal Decomposition technique
• Equivalent but symmetric modes at 3 and 5
• Mode 2: vortex rings aligned with hole axis
• Mode 4: vortex rings misaligned with hole axis
POD pressure modes