S1 Global Plug Compatibility CAD Tools & Collaboration April 23, 2008 Don Mitchell, FNAL.
S1 global: thermal analysis
-
Upload
cassandra-wooten -
Category
Documents
-
view
34 -
download
1
description
Transcript of S1 global: thermal analysis
S1 global: thermal analysis
TILC09, April 19th, 2009
Serena Barbanotti
Paolo Pierini
S1_Global: thermal analysis TILC09 2
Motivation
• Transient thermal modeling of the cooldown behavior of SRF cryomodules can be pushed to include many effects and seems to reproduce data from measurements with sufficient approximation– e.g. WEPD038 at EPAC08 for DESY data
• Models can be developed with increasing complexity as model refinement progresses– e.g. from “lumped” loads to realistic
conduction paths, from convective film coefficients to heat exchange with 1-D fluid channels...
S1_Global: thermal analysis TILC09 3
from WEPD038@EPAC08
• ANSYS FEA against DESY CMTB data
T on 70 K shield T on 5 K shield
S1_Global: thermal analysis TILC09 4
S1-Global
• The S1-Global will have many thermal sensor for the measurement of all heat loads to the cold mass (see Norihito talk), so it make sense to try now pushing our modeling capabilities and see where we end in the comparison– aim is not the load budget, but mainly
temperature distribution– validate models and explore design variations
more cheaply and rapidly (e.g. 5 K yes/no experiments)
• work in progress, benchmarking model
S1_Global: thermal analysis TILC09 5
S1-Global model
• Module C: 3D CAD simplified model– “heavy” defeaturing of nuts, bolts, fillets…
• Included components:– 2 support posts– 70 K/ 5 K shields (integrated cooling channels)– Gas Return Pipe (including cavity supports)– Invar rod (fixed at GRP, fixing cavity z pos)– Cavities in Helium tanks, separated by bellows – Simplified model for coupler conduction paths
to shield and 2 K level
• Large use of frictionless “contacts”
S1_Global: thermal analysis TILC09 6
Thermal modeling
• Full non-linear material properties vs T• Conduction
– Explicitly modeled conduction path for the support of the cold mass through the posts
– Couplers: simplified concentrated heat loads from tabular data at the different T intercepts
• Convection– In increasing complexity, first boundary T on
pipes, then exchange through film coeff. (later) • detail only relevant when cooling rate gets faster...
• Radiation– as a flux on cold surfaces, assuming MLI
S1_Global: thermal analysis TILC09 7
70 K shield
S1_Global: thermal analysis TILC09 8
4 K shield
S1_Global: thermal analysis TILC09 9
Post and invar rod
Fixed invar rod position to GRP
300 K
70 K
5 K
2 K
S1_Global: thermal analysis TILC09 10
GRP and string support parts
C-block for supporting cavity at pads (asfrictionless contacts)
S1_Global: thermal analysis TILC09 11
Cavities (simplified)
Connection to invar rod
Beam pipe bellow(very soft component)
Coupler port (Heat sinkfor tabular 2 K load...)
Pads
S1_Global: thermal analysis TILC09 12
1° case: Static Loads
• Imposed boundary temperatures:– 300 K at upper post surface– 77 K at shield cooling pipe surface– 5 K at shield cooling pipe surface– 2 K at GRP and tank surfaces
• Heat flux (radiation through MLI):– 1 W/m2 at 77 K shield surface– 0.05 W/m2 at 5 K shield surface
• Heat flow (conduction of RF cables/couplers):– 0.1 W at 2 K coupler port on cavity– 1.0 W at the thermalization on 5 K shield– 8.9 W at the thermalization on 77 K shield
S1_Global: thermal analysis TILC09 13
Data for static loadsData from Tom Petersen (FNAL)
2K notes
RF load =0 (static)
Supports Through model
Input coupler See table
HOM coupler (cables) See table
HOM absorber = 0
Beam tube bellows = 0
Current leads = 0 (no quad)
HOM to structure = 0
Coax cable = 0
Instrumentation taps = 0
5K / 77K
Radiation From MLI data
Supports Through model
Input coupler See table
HOM coupler (cables) See table
HOM absorber = 0
Current leads = 0 (no quad)
Diagnostic cable to be calculated
Literature data
Radiation W/m2 heat flux at shield surfaces
2K -
5K 0.05
77K 1
Conduction at couplers W heat flow on coupler thermal intercepts
2K 0.08 Scaled from TTF data presented at Linac04
5K 0.8
77K 7.6
Conduction of RF cables W heat flow on coupler thermal intercepts
2K 0.005 Scaled from Tesla TDR data
5K 0.2
77K 1.275
Total conductionat coupler W effective heat flow on the model
2K 0.1
5K 1.0
77K 8.9
S1_Global: thermal analysis TILC09 14
Computed static heat loads
• At 2 K: 0.14 W• At 5 K: 4.0 W (radiation ~0.7 W)• At 77 K: 43.3 W (radiation ~ 16 W)
static analysis
S1_Global: thermal analysis TILC09 15
Static simulation: results
Gradient on 77 K shieldGradient on 5 K shield
Conduction path only throughwelded fingers(worst case of no thermal contact between mating surfaces ands strong choking of thermal flux)
S1_Global: thermal analysis TILC09 16
Results: GRP, shapes, invar
S1_Global: thermal analysis TILC09 17
Results: cavity string
Heat flux
S1_Global: thermal analysis TILC09 18
Results: heat flux
S1_Global: thermal analysis TILC09 19
Structural analysis, deformations
Fixed post
Sliding post@ 3200 mm
S1_Global: thermal analysis TILC09 20
Vertical displacement…
S1_Global: thermal analysis TILC09 21
Longitudinal behavior
Fixed invar rod position
Position of cavity follows invar rod...
S1_Global: thermal analysis TILC09 22
Evident comparing with GRP
Longitudinal cavity positiondecoupled from GRP,follows invar
S1_Global: thermal analysis TILC09 23
Structural analysis, stresses
Finger welds relieve shield structure from stresses (by design)Stress concentration clearly higher where Al sheet is thinner
S1_Global: thermal analysis TILC09 24
Transient loads: T decrease
0
25
50
75
100
125
150
175
200
225
250
275
300
0 5 10 15 20 25 30 35 40 45 50Time (h)
Te
mp
era
ture
(K
)Temp 77 K Temp 5 K Temp 2 K
Approximation to convectiveexchange: boundary condition on piping with linear decrease of T in time
S1_Global: thermal analysis TILC09 25
Scaling of transient loads
0
1
2
3
4
5
6
7
8
9
10
11
12
0 50 100 150 200 250 300
Temperature (K)
Con
duct
ion
at c
oupl
ers
(W)
Conduction 77K Conduction 5K Conduction 2K
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
0 100 200 300
Temperature (K)
Ra
dia
tion
(W
/m2
)
Radiation 77K radiation 5K
S1_Global: thermal analysis TILC09 26
Transient simulation: results
S1_Global: thermal analysis TILC09 27
0
50
100
150
200
250
300
0 5 10 15 20 25 30 35
Time (h)
T (
K)
T pipe (K) T shield (K) Delta T (K)
Transient T on the 77 K shield
Maximum gradient: 52.2 Kafter ~22 hours of cooldown
S1_Global: thermal analysis TILC09 28
Transient T on the 5 K shield
0
50
100
150
200
250
300
0 5 10 15 20 25 30 35
Time (h)
T (
K)
T pipe (K) T shield (K) Delta T (K)
Maximum gradient: 42 Kafter ~19 hours of cooldown
S1_Global: thermal analysis TILC09 29
T distribution at max T
5 K shield
77 K shield
to do
Stressanalysisat maxgradient on structures
S1_Global: thermal analysis TILC09 30
Next steps: on model
• Perform stress analysis with temperature distribution corresponding to the maximum gradient on the inner cold mass components
• Increasing model complexity– Perform simulations with convective exchange
at pipe surfaces (instead of fixed temperatures)
• Later, possibly coupled to 1-D fluid elements for longitudinal gradients and heat exchange with fluid flowing in cooling channels
– More accurate conduction paths (couplers?)
S1_Global: thermal analysis TILC09 31
Next steps: analysis & benchmark
• Use KEK cooldown procedure as input data for the transient simulation– gather all fluid parameters and evolution with
time (mass flow, pressure condition, etc.)
• Verification of analysis with experimental data collected at KEK by S1_Global collaboration during cryomodule tests– How far can we rely on simulations with
increasing complexity for the assessment of different module designs?