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Fluidised Powder Rig Development
Work by:Ottone Caretta, Peter Loveridge and Chris Denham (RAL)
Tom Davies (Exeter University)Richard Woods (Gericke Ltd.)
With special thanks to EPSRC Engineering Instrument Poolwww.eip.rl.ac.uk
Presented by Ottone CarettaO.Caretta@rl.ac.uk
UKNF Meeting, OxfordJune 2010
Is there a ‘missing link’ target technology?
Some potential advantages of a flowing powder:Resistant to pulsed beam induced shock waves
Favourable heat transfer
Quasi-liquid
Few moving parts
Mature technology
Areas of concern can be tested off-line
Open jets
SOLIDS LIQUIDS
Monolithic Flowing powder Contained liquidsSegmented
Schematic layouts of flowing powder targets for neutrino facilities
Superbeam target - contained within pipe
Neutrino factory target - open jet configuration used in test rig on day 1
(for MERIT comparison)
(1) pressurised powder hopper, (2) discharge nozzle, (3) recirculating helium to form coaxial flow around jet, (4) proton beam entry window, (5) open jet interaction region, (6) receiver, (7) pion capture solenoid, (8) beam exit window, (9) powder exit for recirculation, (10) return line for powder to hopper, (11) driver gas line
The rig
• Powder– Rig contains 150 kg Tungsten– Particle size < 250 microns
• Total ~8,000 kg powder conveyed– 90 ejection cycles– Equivalent to 15 mins continuous
operation
• Batch mode– Test out individual handling processes
before moving to a continuous flow loop
1
2
3
4
1. Suction / Lift2. Load Hopper3. Pressurise Hopper4. Powder Ejection and Observation
Ottone Caretta, Oxford, Nov 09
Experiments: the fun part!
Turbulent flow ~3bar
Dune flow ~1.5bar
Pulsing flow ~1.5bar Coherent jet ~2bar
Ottone Caretta, Oxford, Nov 09
Areas of work
1. Measure density and variations of
2. Obtain as high an coherent density as possible
3. Match the suction and ejection rates currently 1:10 ratio (necessary for continuous operation)
4. Minimise wear of the system and of the powder
Pulsing flow ~1.5bar Coherent jet ~2bar
1. PIV
2. Improve powder flow path
3. Optimise the suction cycle
4. Eliminate design flaws from the rig
Coherent jet characterisation
Coherent Jet workout
– Tungsten powder <250 um– 2.0 bar ejection hopper pressure– Jet “droops” by ~30 mm over a 300 mm length– Each particle takes ~0.1 sec to traverse
viewport– Coherent flow with separation between the 2
phases– Constant pressure in hopper throughout
ejection– Small velocity gradient from top to bottom– Velocity constant over time– Cross section of the jet remains constant
as the jet flows away from the nozzle– Geometry of the jet remains reasonably
constant with timeLow pressure ejection schematic
Vjet = 3.7 m/s
Vair ~30 m/s
Still from video clip(2 bar ejection hopper pressure)Ottone Caretta, Oxford, Nov 09
Jet Density Calculation
From hopper load-cell data log:63 kg in 8 sec = 7.875 kg/sec
h ID
Nozzle ID = 21.45 mmJet height = 14.6 mmJet Area = 262 mm2
• Recall: Solid Tungsten density = 19,300 kg/m3• Powder density “at rest” ~ 50% solid
Density Calculation for 2 bar ejection
Jet area, A= 262 mm2
(from nozzle dimensions and video still measurements)
Powder bulk velocity, V = 3.7 m/s
(from particle tracking)
Vol flowrate = A.V = 0.000968 m3/s
Mass flowrate = 7.875 kg/s
(from loadcell)
Jet Density = Mass flowrate / Vol flowrate = 8139 kg/m3
Jet Density = 42% Solid tungsten density
Uncertainty is of the order ± 5% density
Ottone Caretta, Oxford, Nov 09
Open Source - Particle Image Velocimetry (PIV)
– http://www.openpiv.net/– Allows calculation of relative velocities
between pairs of subsequent images.– Velocities can be scaled in space and time
Ottone Caretta, Oxford, Nov 09
PIV - Highlighting the odd grains
– Original images
– Average images
– Negative image (subtracted the average image) this highlights the odd grains
Ottone Caretta, Oxford, Nov 09
PIV – velocity range selector
– Allows taking out fringes and mistaken points from the average calculation
Ottone Caretta, Oxford, Nov 09
PIV - example
Ottone Caretta, Oxford, Nov 09
PIV – vertical velocity profile in the jet
Ottone Caretta, Oxford, Nov 09
Variations in the flow rate – typical 2bar ejection
How much material does the beam meets?
Density?
Is the amount of material in the nozzle (or jet) constant?
Ottone Caretta, Oxford, Nov 09
Ottone Caretta, Oxford, Nov 09
Future experiments – prevent phase separation
The commercial dense phase conveyer is
less than ideal!
Sharp bend
Horizontal reducer
Unused lower air supply
Vertical reducer (near continuous)
Long radius bend
Future experiments – artificial/regular slug formation
Ottone Caretta, Oxford, Nov 09
Pulsed air injection
Separate, bunch and accelerate slugs
Future experiments – continuous recirculation (contained target)
Ottone Caretta, Oxford, Nov 09
Analytical study on lifting power requirements
Ottone Caretta, Oxford, Nov 09
0 2 4 6 8 10 12 14 160
1000
2000
3000
4000
5000
6000
7000
8000
lifting work vs suction capacity
Powder Mass flow rate [kg/s]
Th
eore
tica
l li
ftin
g p
ow
er [
W]
Powder lifting flow rate depends on a few variables:
– Powder entrainment in the air stream– Powder size distribution– Sphericity of the grains– Diameter of the suction line– Air to powder ratio– Density of the powder– Density of the gas– Temperature of the gas– Etc.!
The blower in the rig (18kW) has so far been able to lift at 1kg/s vs an
ejection rate of ~10kg/s
But there is hope!
Different density requirements for Superbeam and NuFact
Ottone Caretta, Oxford, Nov 09
High density tungsten for NuFact
Low density alumina for Superbeam?
Thank you!
Q & A?
Ottone Caretta, Oxford, Nov 09
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