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