LHC Phase II CollimatorCompact jaw simulations
• New FLUKA => ANSYS mapping scheme
• New 136mm x 950mm jaw– 60cm primary collimator– Helical cooling channel / hollow core– 360o cooling / “solid” core
Mapping FLUKA => ANSYSOriginal Scheme
• 10x10x24 FLUKA bins mapped to ANSYS elements, one for one
• Energy density of FLUKA bin applied to ANSYS element
• Outer row of ANSYS mesh sized equal to FLUKA
• On average, less volume in ANSYS model, therefore less tot energy
• Bins with poorest match contain least energy
Mapping FLUKA => ANSYSnew scheme & comparison
• ANSYS nodes located within FLUKA bin are assigned energy density of that bin
Power - 150mm diam x 1.2m long jaw
Power (KW)
1hr lifetime
FLUKA 10.41
Original mapping 9.13
New mapping 9.12
Mapping FLUKA => ANSYSnew & old schemes compared
• Peak temperatures generally slightly lower
• Net energy deposit ~ same (previous slide)
• Deflection up to 16% lower
• due to different energy distribution (?)
• Both models sufficiently accurate for engineering purposes
material coo
lin
g a
rc (
deg
)
po
wer
(kW
) p
er j
aw,
no
min
al
Tm
ax (
C)
Tm
ax w
ater
sid
e (
C)
def
l (u
m)
po
wer
(kW
)
Tm
ax (
C)
Tm
ax w
ater
sid
e (
C)
def
l (u
m)
Cu - solid 37 10.4 85 65 60 52 213 542
Cu, solid, 150x1200, original model 36 10.4 87.6 66 49.5 52 208.4 127 494
Cu - solid, 150x1200 37 15.8 113 80 93 79 297 180 855
Cu - solid, 150x1200 36 15.8 110.8 82.8 72.5 79 271.7 164 752
original mapping scheme benchmarks
10 s, primary debris + 5% direct hits
7 s, no pre-radiator
SS @ 1 hour beam life transient 10 sec @ 12 min beam life
Conceptual design - coolant channels
Limited cooling arc: free wheeling distributor – orientation controlled by gravity – directs flow to beam-side axial channels.
Pro: Far side not cooled, reducing T and thermal distortion.
Con: peak temperature higher; no positive control over flow distributor (could jam); difficult fabrication.
360o cooling by means of helical (or axial) channels.
Pro: Lowers peak temperatures.
Con: by cooling back side of jaw, increases net T through the jaw, and therefore thermal distortion; axial flow wastes cooling capacity on back side of jaw.
water
beam
Helical cooling passages – fabrication conceptPreferred design due to fabrication ease, minimal weld or braze between water & vacuum
1. Tube formed as helix, slightly smaller O.D. than jaw I.D.
2. O.D. of helix wrapped with braze metal shim
3. Helix inserted into bore, two ends twisted wrt each other to expand, ensure contact
4. Fixture (not shown) holds twist during heat cycle
Variations:
1. Pitch varies with length to concentrate cooling
2. Two parallel helixes to double flow
3. Spacer between coils adds thermal mass, strength
4. Fabricate by electroforming on helix
New “Compact” Jaw• Original jaw: 150mm diam x 1.2m long
– Won’t fit available space - limited by beam spacing• New jaw: 136mm diam x .95m long , including 10cm
tapered ends– Tank 72mm wider & 22mm deeper– 45mm max aperture
Simulations – Evolution of ANSYS model
Water cooled
2-d model
25 x 80mm grid
FLUKA generated energy deposit at shower max
3-d model
FLUKA generated energy deposit mapped to blue area
Water cooling:
assume sufficient water that temperature is constant
360o complete I.D. cooled
~45o between arrows cooled => less distortion
136mm x 25mm wall
x1200mm long
136mm
x1200mm long
“Solid” model
Solid core => less distortion
Cooling channel:
~45o arc between arrows (modeling expedient)
Cooling applied to OD only of slot
Evolution of ANSYS models
136mm
x 950mm long
53o cooling arc
2x 5mm sq channels
Compact geometry
OD and length reduced to fit space constraints
Water cooling:
Various arc lengths modeled
assume sufficient water that temperature remains constant
Tubular cooling channels
More realistic modeling of heat path
Water cooling:
Circumference of square tubes cooled – area equal to 53o arc
5mm sq tubes equivalent cross section to 6mm diameter
Assume sufficient water that temperature remains constant
136mm
x 950mm long
Evolution of ANSYS Models
136 OD
x 71 ID
x 950 L
Uniform ID Cooling
Approximates effect of helical or axial flow
Water cooling:
assume sufficient water that temperature remains constant
H2O simulation – helical flow shown
Fluid pipe elements:
Water temperature responds to heat absorbed from jaw
More realistic simulation
Axial pipes can simulate axial flow
Friction can be simulated
beam
Compact (136x950) jaw variations - performance comparison
12
345
6789
material coo
lin
g a
rc (
deg
)
po
wer
(kW
) p
er j
aw,
no
min
al
Tm
ax (
C)
Tm
ax w
ater
sid
e (
C)
def
l (u
m)
po
wer
(kW
)
Tm
ax (
C)
Tm
ax w
ater
sid
e (
C)
def
l (u
m)
Cu - solid, 150x1200 37 10.4 85 65 60 52 213 542
Cu, solid, 150x1200, original model 36 10.4 87.6 66 49.5 52 208.4 127 494
Cu - solid, 150x1200 36 11.3 89.1 67 49.5 57 210.2 129 520
Cu-solid, 136x950 40 11.3 92 71 53 57 213 133 526
Cu-solid, 136x950 53 11.3 80 59 54 57 203 126 525
Cu solid, 136x950, 2 channels - 11.3 84 60 73 57 201 104 551
Cu solid, 136x950, 2 ch, fluid pipes - 11.3 85 55 63 57 201 86 540
Cu, 136x71x950 (helical) - 11.3 58 40 179 57 178 99 688
Cu, 136x71x950 (helical), fluid pipes - 11.3 78 281 57 205 869
original mapping scheme benchmarkssimulated beam side-only coolingsimulated all-around cooling (helical flow)
10 s, primary debris + 5% direct hits
7 s, no pre-rad, 60cm prim
SS @ 1 hour beam life transient 10 sec @ 12 min beam life
Compact (136x950) jaw variations – compare simulation models
Compact (136x950) jaw variations – compare design concepts
• Preferred: helical flow concept– Pro
• less water-vacuum weld/braze
– Con• Excessive deflection – 280um SS
• Secondary: beam side only axial flow concept– Pro
• Less deflection – 63um SS
– Con• More water/vacuum weld/braze• Mechanically risky flow distributor