Fluidised Powder Rig Developments

Work by:Chris Densham, Peter Loveridge & Ottone Caretta (RAL)

Tom Davies (Exeter University)Richard Woods (Gericke Ltd.)

With special thanks to EPSRC Engineering Instrument Poolwww.eip.rl.ac.uk

Presented by Peter LoveridgeP.Loveridge@rl.ac.uk

UKNF Meeting, LancasterApril 2009

Why a Powder Target?

• A fluidised powder could be considered for future high power target scenarios:

– Neutrino Factory target• Open (or contained?) jet in solenoid• Alternative to liquid Mercury baseline

– Superbeam• Contained flowing powder + horn• To go beyond “power limit” in solid

graphite targets

• Tungsten Powder test programme launched– Test rig commissioned Dec 2008 at RAL– First results Mar 2009

Rig Commissioning, RAL, Dec 2008

• A fluidised powder has some of the advantages of both solid and liquid targets:– Material already broken (no fear of rupture)– Shock waves constrained within material, i.e. no splashing or cavitation– Flowing, replenishable material– Favourable heat-transfer– Decoupled (offline) cooling– Few moving parts– Powder handling is a mature process technology (ready solutions for most issues)

Rig Operation Overview• Powder recirculated in “Batch” mode

– Rig contains ~130 kg Tungsten Powder– Particle size < 250 microns

• Fully automated control system– Valve open/close sequence– Blower on/off– Blower Frequency– Data Logging– Hard-wired safety interlocks

Batch Powder Process1. Load Hopper2. Pressurise Hopper3. Powder Ejection and Observation4. Suction / RecirculationControl System User Interface (MATLAB)

1

2

3

4

Summary of Data runs 18 March – 01 April

• Total ~3,000 kg powder ejected– 31 suction/ejection cycles

• Parameters Varied:– Conveying pressure range 2 to 5 bar– Coaxial flow geometry– Coaxial flow velocity 10 – 30 m/s

• Powder jet recorded using High-speed camera– Vision Research PHANTOM 7.1– 5000 fps

• Rig instrumentation data logged throughout– Pressure– Flowrate– Temperature– Mass

High speed camera setup

Post-processing Underway

• Data interpretation underway…– Preliminary results available

Results for a Low Pressure Jet

• Low pressure ejections look quite promising– 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– Jet Velocity = 3.7 m/s– Nozzle pipe not full!

• Stable Jet– Constant pressure in hopper throughout

ejection– Velocity (does not vary top/bottom)– Velocity (constant over time)– Dimensions (constant with distance from

nozzle)– Dimensions (reasonable stability over time)

Low pressure ejection schematic

Vjet = 3.7 m/s

Vair ~30 m/s

Still from video clip(2 bar ejection hopper pressure)

Video Clip

High-Speed Video Clip(2 bar ejection hopper pressure)

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

Summary

• Rig commissioning complete in 1st (simple) configuration

• Data runs Mar/Apr 2009

• Preliminary results indicate a jet density 42 ± 5 % is feasible– 42% Tungsten density is equivalent to 60% Mercury Density

Next Steps

• Ongoing evaluation of data runs

• Hardware– Reconfigure rig for vertical powder lift (without 90 degree bend

in suction line)– Install nozzle pressure sensors

• Experiments– Powder flotation, minimise velocity and wear in suction cycle– Nozzle pressure drop– Test minimum flow velocity (for contained powder target)

• Next EIP camera slot in June?

Suc

tion

Gra

vity

Next Configuration (vertical powder lift)