LHC Phase II Collimator Compact jaw simulations

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LHC Phase II CollimatorCompact jaw simulations

• New FLUKA gt ANSYS mapping scheme
• New 136mm x 950mm jaw
• 60cm primary collimator
• Helical cooling channel / hollow core
• 360o cooling / solid core

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Mapping FLUKA gt 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

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Mapping FLUKA gt ANSYSnew scheme comparison

• ANSYS nodes located within FLUKA bin are assigned
  energy density of that bin

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Mapping FLUKA gt 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

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Conceptual design - coolant channels
beam
water
Limited cooling arc free wheeling distributor
orientation controlled by gravity directs flow
to beam-side axial channels. Pro Far side not
cooled, reducing DT 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 DT
through the jaw, and therefore thermal
distortion axial flow wastes cooling capacity on
back side of jaw.
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Helical cooling passages fabrication
concept Preferred design due to fabrication ease,
minimal weld or braze between water vacuum

• Tube formed as helix, slightly smaller O.D. than
  jaw I.D.
• O.D. of helix wrapped with braze metal shim
• Helix inserted into bore, two ends twisted wrt
  each other to expand, ensure contact
• Fixture (not shown) holds twist during heat cycle

• Variations
• Pitch varies with length to concentrate cooling
• Two parallel helixes to double flow
• Spacer between coils adds thermal mass, strength
• Fabricate by electroforming on helix

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New Compact Jaw

• Original jaw 150mm diam x 1.2m long
• Wont 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

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Simulations Evolution of ANSYS model
Water cooled
136mm x 25mm wall x1200mm long
136mm x1200mm long
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 gt less
distortion
Solid model Solid core gt less
distortion Cooling channel 45o arc between
arrows (modeling expedient) Cooling applied to OD
only of slot
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Evolution of ANSYS models
136mm x 950mm long
136mm x 950mm long
2x 5mm sq channels
53o cooling arc
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
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Evolution of ANSYS Models
136 OD x 71 ID x 950 L
beam
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
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Compact (136x950) jaw variations - performance
comparison
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Compact (136x950) jaw variations compare
simulation models
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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