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WP WP F/LF/L
A mechanical design for a detection unit for a deep-sea neutrino telescope
VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
First concept DOMBAR
Fits in ISO container
13/10/2011 2VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
13/10/2011 3VLVnT11 - Edward Berbee - Nikhef
First design
6 mMechanical Cable Connection
Rope & Cable Storage
Rope Storage
Bar Frame
Optical Module
Mechanical Interface
2 DOM + 1 BAR = 1 DOMBAR20 DOMBARS = DOMTOWER
WP WP F/LF/L
Floating problem due to flatness
Because of the “flat” top-view the floor tends to float in horizontal direction.
13/10/2011 4VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
“turning flaps”“hosted hood”“tuning drum”
Other design ideas; abandoned
13/10/2011 5VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Data VEOC
Mechanical cable (Dyneema rope)
VEOC management
2 double reels for unwinding the ropes
13/10/2011 6VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Some design considerations;
-2 ropes wound around braked cable reels (and so under tension) to perform the unfurling controlled.
-Buoyancy on each floor, above the center of gravity to insure horizontal unfurling of the floors.
-Keep the unfurling speed low for better control (but not to low for drifting away due to current).
-Keep the DU-package compact for easy handling and transportation.
-The rope- and cable unfurling as well as all other items should not happen uncontrolled (without tension) at any moment.
13/10/2011 7VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Slightly rotated bar structures for narrow stacking - complicated cable and rope management!
13/10/2011 8VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Unfurling method-In all methods; tension in ropes
absolutely necessary. Unwinding synchronized
necessary?
All in once, then from the bottom off the package.
-Very high unfurling speed at the beginning.
One by one, from the bottom up,
-Unfurling speed more continuous.
Buoyancy on each storey.
No;-Less need for mechanical construction to separate
one by one.
Yes;- Mechanical construction to
separate one by one absolutely necessary.
Buoyancy on each floor.
Yes;-Less need for mechanical construction to separate
one by one.
No;- Mechanical construction to
separate one by one absolutely necessary.
DOMBAR unfurling constrains; choice made
13/10/2011 9VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Possible designPackage; L x W x H 5800 x 2380 x 2050 mm
Fits a “pallet wide” or “flat rack” container
Floors clamped on vertical tubes, pulled off during unfurling, all under discussion.
“flat rack” container
13/10/2011 10VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Storey with yellow vertical optical cables (VEOC) and two double cable reels at the end (internally braked)
Storey buoyancy, syntactic foam; approx. 450 N - 0,1M3 13/10/2011 11VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Verifying stable dynamic behavior
13/10/2011 12VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
-20 bar structures.
-Top buoy.
-3 distance frames.
-Baseframe with clamping tubes.
-2 concrete “Stelcon” plates.
-2 separator racks.
13/10/2011 13VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Possible unfurling
-Buoy is released.
-Buoy pulls of first storey.
-Buoy and first storey will pulloff the second storey etc.
-Released storey will make an approximately 45 degree turn while floating up.
-Tensioned ropes, pull tension approximately 100 N each rope for better control during unfurling.
-Each storey clamped with spring tensioned clamp on 5 vertical tubes, friction on these tubes approx. 500 N.
13/10/2011 14VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Some details
One of the two rollers from the bottom storey to connect to the base frame.
Hinged support plates for stabilizing the end of bar structures.
The three lower storeys are without optical modules.
13/10/2011 15VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
13/10/2011 16VLVnT11 - Edward Berbee - Nikhef
Distance frames, the lower one with running wheelsFor rotating of the DU.
Concrete deadweight, (or steel) captured in aluminum profile.
Lower active Bar
Scaled picture
Lower part of the DU
Not scaled picture
WP WP F/LF/L
13/10/2011 17VLVnT11 - Edward Berbee - Nikhef
Unfurling of a DU scale model from the seabed up
1:50 model area
Real scale area
13/10/2011 18VLVnT11 - Edward Berbee - Nikhef
13/10/2011 19VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Drag coefficients of importance for the DU
For spheres the drag coefficient Cd= 0.5, For the Dom we take (some extra for the interface); In both horizontal and vertical direction Cd = 0.7
Drag of the cables and ropes; Cd = 1.2
Drag coefficient for the aluminum tubes, circular rod, In both horizontal and vertical direction Cd = 1.2
Storey buoyancy; estimated for flow from the top; Cd = 0.9 estimated for flow from the side; Cd = 0.5
Top-buoy; estimated for flow from the top; Cd = 0.8 Estimated for flow from the side; Cd = 0.4
13/10/2011 20VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
0
100
200
300
400
500
600
700
800
900
1000
0 100 200
Hei
ght (
m)
Drift (m)
Hydro dynamic behavior
Characteristics used:
Rope OD (4x) 4 mmVEOC OD (2x) 6.35 mmTop buoyancy 1000 NBar buoyancy 450 NTotal buoyancy 10000 NAnchor 3670 kg (concrete, weight in air)Anchor 2450 kg (steel weight in air)Total transport weight 7420 / 6200 kgTotal weight in sea 1120 kgCalculated drift 165 m @ v = 0.30 m/s
h = 30 cm/s
13/10/2011 21VLVnT11 - Edward Berbee - Nikhef
Used formula;Where: rho = the density of seawater = 1028 kg/m3
v = the speed in m/s Cd = the drag coefficient (dimensionless) A = surface area in m2
WP WP F/LF/L
Influences on the amount of drag
Rope OD (4x) 5 mm (instead of 4 mm)Drift 179 m @ v = 0.30 m/s
VEOC OD (2x) 10 mm (instead of 6.35 mm)Drift 190 m @ v = 0.30 m/s
Some examples compared to the situation of the previous slide (drift 165 m);
Top buoyancy 7000 N (instead of 1000N)Bar buoyancy 150 N (instead of 500N)Total buoyancy 10000 N (still)Drift 130 m @ v = 0.30 m/s
13/10/2011 22VLVnT11 - Edward Berbee - Nikhef
WP WP F/LF/L
Hydro dynamic behavior
In vertical direction (during unfurling)(450 N local buoyancy)Calculated speed of 1000 N top-buoy at start; 1.46 m/sCalculated speed first storey with top-buoy; 1.13 m/sCalculated speed first two floors with top-buoy; 1.03 m/s Calculated speed at the last floor; 0.85 m/s
13/10/2011 23VLVnT11 - Edward Berbee - Nikhef
In vertical direction with a top buoy of 7000 N instead of 1000 N;(150 N local buoyancy)Calculated (vertical) speed top-buoy at start; 2.48 m/sCalculated speed first storey with top-buoy; 2.04 m/sCalculated speed first two floors with top-buoy; 1.79 m/s Calculated speed at the last floor; 0.89 m/s
WP WP F/LF/L
13/10/2011 24VLVnT11 - Edward Berbee - Nikhef
Verifying vertical drag calculation on scale-model
Calculated; 0,060m/s at 0,001 N buoyancy measured speed 0,065 m/s
WP WP F/LF/L
Summary;
Calculation for the deviation of the top relative to the bottom at 0.30 m/s current; (possible to improve by a bigger top-buoy) 165 mCalculated speed of 1000 N top-buoy at start; 1.46 m/sCalculated speed first storey with top-buoy; 1.13 m/sCalculated speed at the last floor; 0.85 m/s
13/10/2011 25VLVnT11 - Edward Berbee - Nikhef