piv experiments on the flow induced by a sphere sedimenting towards a solid wall
DESCRIPTION
The motion induced by gravity of solid spheres in a vessel filled with fluid has been investigated experimentally at Reynolds numbers in the range from 1-74 and Stokes numbers ranging from 0.2-17. Trajectories of the spheres have been measured with a focus on start-up behavior, and on impact with a horizontal wall. Two models have been investigated. The first describes the accelerating motion of the sphere. The second model predicts the distance from the wall at which the sphere starts decelerating.The flow in the vicinity of the sphere was measured by means of PIV. The time scales and flow structures strongly depend on the Reynolds number. Measurements performed are in good agreement with simulations performed at the Kramers Laboratorium.TRANSCRIPT
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PIV-experimenten aan de stroming veroorzaakt door een bezinkende bol
die een horizontale wand nadert
Kees Nieuwstad
19 januari 2001
Begeleiders: ir. A. ten Cate
dr. ir. J.J. DerksenAfstudeerhoogleraar: prof. dr. ir. H.E.A. van den Akker
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Overzicht
Deeltjessnelheid: Baanmetingen• Inleiding
Vloeistofsnelheden: PIV-snelheidsveldmetingen
• Experimentele opstelling
• Experimentele opstelling• PIV-theorie
• Samenvatting resultaten
• Resultaten• Conclusies
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Achtergrond
Simulatie stroming in kristallisator
Kristallen botsen
Opnemen in modellen voor simulaties
Aanpak: simuleer individuele kristallen
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Inleiding
Krachten: Fg, FArch, Fdrag
1-op-1 vergelijking van gecontroleerde situatie
Bol in doos
Hoe valideren?
Res~10-60
Invloed wand doos?
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Mijn doelstelling
Meet voor validatie:
baan van bol stromingsveldstromingsveldvan de vloeistofvan de vloeistof
t ( s )
h(m
)
v pv pv p
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Baanmetingen - Meetopstelling
Naar
vacuüm
Glazen bol
Camera
Elektronische klep
Drukmeter
Glazen plaat
Doos gevuld met vloeistof
p
h x
Kraan Vloeistof:
Glycerol-watermengsel
f
ffs
Dv
µµρ= )(
Re
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Baanmetingen - Test
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Baanmetingen - Ruwe meetdata
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Resultaten - Baanmetingen
5 over elkaar liggende banen: reproduceerbaar experiment
ttt (s)0 0.05 0.15 0.25 0.3
6
8
10
12
13
0 0.05 0.15 0.25 0.30 0.15 0.25 0.3
h/D
Res=74
Vs+=0.29 m/s
Vs=0.34 m/s
Ferreira ‘99
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Resultaten - Baanmetingen
µρ UD
St s
9
1=
Stc ~ 20
s
c
D
h
Re
1~Gondret ’99:
Res=1.5-18.8
t
0
1
2
3
4
5
0 0.1 0.2 0.3 0.4 0.5
h/D
Res
Stmax = 4.4
vloeistofkrachtenvisceuze
deeltjekrachtentraagheids=
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Metingen - Ruwe PIV-data
Res=1.5
PIV: Volgen groepjes 10-20 deeltjes
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Meting - Interrogatie
Volgen van bol: lastig Volg witte bovenkant
Bol: zwart gemaakt
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Meting - Kruiscorrelatie
t
t+∆t
Voor PIV interrogatie wordt PIVWare (J. Westerweel) gebruikt
Kruis-correlatie PIV
1111
3232
32321200001100001000009000080000700006000050000400003000020000100000
Intensiteit
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Resultaat - Stationair
Res= 1.5
0 1 2 3 4x(cm)
0
0.5
1
1.5
2
2.5
3
3.5
4
y(cm)
5cm/s
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PIV-criteria
PIV criteria:IHV-verplaatsing < ¼ IG
Snelheidsverschil in IG < 5%
Mijn opstelling
Erg klein: geen probleemUHV-verplaatsing < ¼ sheetsheetdikte
|v|vff||maxmax = 17 cm/s = 17 cm/s
t t+∆t
Laminaire stroming,zie experiment
fcamera,max=250 Hz
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PIV-Meetopstelling
Nylon deeltje: ρp=1120 kg/m3, dp=15 mm
Vloeistof: siliconen olie
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15 mm
45 mm
45 mm
32 mm
32 mm
Metingen - Cases
Varieer Res door µf en ρf te veranderen
16 cm
µf
(mPas)
Vandaag: voornamelijk nadering van bodem bak
58
373
3(kg/m
960
970
ρ f
)
32
1.5
Res
Res dan Lf : meetgebied groter
Lage ResHoge Res
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0
1
2
3
4
5
6
7
8
-0.5 0 0.5 1 1.5 2 2.5 3 3.5 4
h/D
(-)
t (s)
Res= 1.5
2 metingen
Resultaat - Reproduceerbaarheid
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Resultaat - Reproduceerbaarheid
Res= 1.5Twee keer hetzelfde experiment
hbol is ongeveer hetzelfde
1.000.930.860.790.710.640.570.500.430.360.290.210.140.070.00
|v|vff|/v|/vss
0 1 2 3x/D(-)
0
1
2
3
y/D(-)
V1.000.930.860.790.710.640.570.500.430.360.290.210.140.070.00
0 1 2 3x/D(-)
0
1
2
3
y/D(-)
V1.000.930.860.790.710.640.570.500.430.360.290.210.140.070.00
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Resultaat - Nadering van de wand
Res=1.5
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0 1 2 3x/D(-)
0
0.5
1
1.5
2
2.5
3
y/D(-)
0 1 2 3x/D(-)
0
0.5
1
1.5
2
2.5
3y/D(-)
0 1 2 3x/D(-)
0
0.5
1
1.5
2
2.5
3
y/D(-)
Resultaat - Nadering van de wand
.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.050
|v|vff|/v|/vss
01
Res=1.5
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0 1 2 3x/D(-)
0
0.5
1
1.5
2
2.5
3
y/D(-)
0 1 2 3x/D(-)
0
0.5
1
1.5
2
2.5
3
y/D(-)
Resultaat - Vergelijking
Interessant: • Vloeistofsnelheid
Res=32 Res=1.5 1.000.930.860.790.710.640.570.500.430.360.290.210.140.070.00
|v|vff|/v|/vss
• Plaats van circulatie
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Resultaat - Tijdreeksen
t (s)
0
0.05
0.1
0.15
0.2
0.25
0 1 2 3 4 5
|v|vff|/
v|/vss
Res=32
0
0.05
0.1
0.15
0.2
0.25
0 1 2 3 4 5
t (s)
Res=1.5
1
1
Monitorpunt
0
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Resultaat - Vergelijking met simulaties
t (s)
Simulaties zijn gedaan door A. ten CateSimulaties zijn gedaan door A. ten Cate
0
1
2
3
4
5
6
7
8
9
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
h/D
(-)
Res=1.5-32
Res
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Resultaat - Vergelijking met simulaties
SimulatieSimulatie MetingMetingRes=32
.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.050
|v|vff|/v|/vss
01
0 0.5 1 1.5 2x/D(-)
0
1
2
y/D(-)
0.5 1 1.5 2x/D(-)
0
1
2
y/D(-)
V10.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.050
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Conclusies
• Kogelbanen en vloeistofsnelheden zijn gemeten
• Tijdschalen en stromingsstructuren hangen sterk van het Reynoldsgetal af
• Dataset voor validatie van simulaties is verkregen
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Aanbevelingen
• Achter de bol meten. Laat sheet van de zijkant het bakje in komen
• Bepaal zo nauwkeurig mogelijk Stc
• Bestudeer stromingsveld van twee naast elkaar vallende bollen
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Vragen?