FLOW CONDITIONING FLOW CONDITIONING DESIGN IN TURBULENT DESIGN IN - - PowerPoint PPT Presentation
FLOW CONDITIONING FLOW CONDITIONING DESIGN IN TURBULENT DESIGN IN TURBULENT LIQUID SHEETS LIQUID SHEETS S.G. DURBIN, M. YODA, and S.I. ABDEL-KHALIK G. W. Woodruff School of Mechanical Engineering Atlanta, GA 30332-0405 USA Thick Liquid
S.G. DURBIN, M. YODA, and S.I. ABDEL-KHALIK
Mechanical Engineering Atlanta, GA 30332-0405 USA
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“curtain” to absorb radiation from fusion events
HYLIFE-II
create protective pocket to shield chamber side walls
front/back walls while allowing beam propagation and target injection
(High-Yield Lithium-Injection Fusion Energy)
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edge of liquid sheet and driver beams
Minimize interference with target injection, beam propagation How are velocity fluctuations near the nozzle exit influenced by different flow conditioner (vs. nozzle) designs? How are velocity fluctuations related to free-surface fluctuations downstream of the nozzle exit? Are fine screens required in the flow conditioner? Will more screens reduce free-surface fluctuations?
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A Pump H 400 gal tank B Bypass line I Butterfly valve C Flow meter J 700 gal tank D Pressure gage K 20 kW chiller A B C D E E F F H I J K G G
E Flow conditioner E Flow conditioner F Nozzle F Nozzle G Liquid sheet G Liquid sheet
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[Re = Uoδ / ν; Uo average speed; ν liquid kinematic viscosity]
u and u′ : Streamwise (x-component) w and w′ : Transverse (z-component)
z y x δ
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Open area ratio 50% with staggered 4.8 mm dia. holes
3.2 mm dia. × 25.4 mm staggered circular cells
Open area ratio 37.1% 0.33 mm dia. wires woven w/ open cell width of 0.51 mm (mesh size 30 × 30)
Open area ratio 36.0% 0.25 mm dia. wires woven w/ open cell width of 0.38 mm (mesh size 40 × 40)
5th order polynomial contour with contraction ratio = 3
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x y z HC PP FS-1
3.9 cm 3.0 cm 14.7 cm 3.3 cm
FS-2 x y z HC PP
3.9 cm 3.0 cm 14.7 cm
(FS-1)
No Screen / (One Screen*) Two Screens
* Standard design
LDV window
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w measurements
µm (x, y, z) at FWHM
linear stages
particles (typical dia. 0.3 µm)
b = 10.95 mm
z x y g
b x z y Probe shown in streamwise configuration
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(bright) water and (dark) air
Exposure one convective time scale τ = δ / Uo = 0.9 – 2.2 msec
Threshold value from image grayscale histogram Grayscale > threshold ⇒ water ≤ threshold ⇒ air
Light sheet CCD Nozzle x z y g Original image Thresholded image Free surface
1 cm x y z
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0.00 0.25 0.50 0.75 1.00
0.00 0.25 0.50 z / t(x) u / Uo
0.00 0.05 0.10 0.15 w / Uo
y / δ
4.838
4.438 4.163
3.688
+ 1.188
b = 10.95 mm
b x z y
z / b
z y x b
Profiles along dotted lines
w / Uo
u / Uo
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0.00 0.25 0.50 0.75 1.00
0.00 0.25 0.50 z / t(x) u / Uo
0.00 0.05 0.10 0.15 w / Uo
0.00 0.25 0.50 0.75 1.00
0.00 0.25 0.50 z / t(x) u / Uo
0.00 0.05 0.10 0.15 w / Uo
y / δ
4.838 4.438 4.163 3.688
+ 1.188
No Screen Two Screens
z / b z / b
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1 2 3 4 5
0.00 0.25 0.50 z / t(x) RMS / Uo (%)
turbulence
u′ / w′ ≈ 2
fluctuations for central 75% of b
layer indicated by marked increase in u′, w′ near nozzle walls
y / δ
4.838
4.438 4.163
3.688
+ 1.188
w′ / Uo
u′ / Uo
z / b rms / Uo (%)
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1 2 3 4 5
0.00 0.25 0.50 z / t(x) RMS / Uo (%)
y / δ
4.838 4.438 4.163 3.688
+ 1.188
No Screen Two Screens
1 2 3 4 5
0.00 0.25 0.50 z / t(x) RMS / Uo (%)
z / b z / b rms / Uo (%) rms / Uo (%)
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1.9 2.5 2.6 Average 2.4 2.5 2.438 1.8 2.3 2.6 3.688 1.7 2.6 2.6 4.163 2.0 2.5 2.6 4.438 2.0 2.4 2.6 4.638 2.0 2.6 2.6 4.838 Two Screens One Screen No Screens y / δ u' / Uo (%)
≤ 0.375
interval for all data ~0.1 %
less streamwise fluctuation
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1.0 1.1 1.3 3.688 1.2 1.2 1.5 Average 1.0 1.0 1.9 1.188 1.0 1.0 1.1 2.438 1.0 1.1 1.4 4.163 1.0 1.0 1.4 4.438 1.2 1.3 1.5 4.638 1.9 1.7 1.7 4.838 Two Screens One Screen No Screens y / δ w' / Uo (%)
disturbance without screen
w′ / Uo = 1.6 – 2.3 % at y / δ = 1.638 – 0.338, respectively
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fluctuation without fine screen
Also observed in transverse velocity fluctuations
No Screen One Screen
0.00 0.05 0.10 0.15
0.0 2.5 5.0 y / δ σz / δ
z y x
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0.00 0.02 0.04 0.06 0.08 10 20 30 x / δ σz / δ
flows without fine screen
Due to central disturbance
and two screen flow conditioning
No Screen One Screen Two Screens σz / δ
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configuration produces smoother jet
transverse rms identical within experimental error
One Screen Two Screens
0.00 0.01 0.02 0.03 0.04 0.05 10 20 30 x / δ σz / δ σz / δ
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flow conditioner assembly, ρL = fluid density, Uin = inlet velocity, and Uo = exit velocity
increases loss coefficient
Pumping power ↑ as KL ↑ for given flowrate
2 2
12 12 ∆ + =
L L
P ρ ρ
in L
K U
2.11 10.84 2.38 121 Two Screens 1.84 10.75 2.36 103 One Screen 1.25 10.72 2.35 69 No Screens KL Uo (m/s) Uin (m/s) ∆P (kPa)
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nozzle exit
Streamwise velocity measurements indicate uniform flow for all flow conditioner configurations Second screen decreases streamwise velocity fluctuations Elevated levels of transverse velocity fluctuations in center of jet for conditioning without a fine screen
Addition of fine screens increases KL
– Requires higher pumping power – Increases likelihood of flow blockage due to trapped debris
Characterized turbulent liquid sheets from three flow conditioning configurations for Re = 50,000 and 120,000
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One screen configuration produced smoothest flows for Re = 50,000 and 120,000
– σz / δ < 0.04 in near-field – Second screen increases surface ripple at Re = 50,000
Central disturbance observed in transverse velocity fluctuations and free-surface fluctuations for conditioning with no screen
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number show:
One and two screen configurations meet HYLIFE-II surface ripple requirement of σz < 0.07δ One screen best practical configuration
– Lower pumping power – Less likely to trap debris
Fine screen necessary to produce smooth free surface
– Transverse fluctuations appear to be more correlated to free-surface fluctuations
Free-surface behavior highly sensitive to initial conditions
– Must prevent blockages to avoid flow disruptions
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Research Staff: D. Sadowski and S. Shin Students: T. Koehler, T. Durbin, and B. Shellabarger
Grant DE-FG02-98ER54499