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On Cavitation Nuclei in Water Tunnels. Singapore. Paper 270. H.- J. Heinke C. Johannsen Ship Model Basin (SVA) Potsdam Hamburg Ship Model Tank (HSVA) W. Kröger P. Schiller E.-A. Weitendorf - PowerPoint PPT Presentation
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On Cavitation Nuclei in Water Tunnels
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Paper 270
H.- J. Heinke C. Johannsen Ship Model Basin (SVA) Potsdam Hamburg Ship Model Tank (HSVA)
W. Kröger P. Schiller E.-A. Weitendorf University Rostock Hamburg University of Technology Consultant, Hamburg
(TUHH)
Singapore
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The Three Cavitation Tunnels Used
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Time Dependent Nuclei and Oxygen Content with Pressures in Berlin Tunnel K27 without Model
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2D-Profile Cavitation Test in Berlin Tunnel K27
Speed VA = 5.5 m/s and angle of attack (α + α0) = 10°
2D-Profile in Berlin Tunnel K27 at VA = 5.5 m/s, cav-number Ϭ = 2.0 and and angle of attack = 10°
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2D-Profile in tunnels K15A and K27 at VA = 5.5 m/s, cav-number Ϭ = 1.5 and and angle of attack = 10°
SVA Potsdam Tunnel K15A(Small Test Section)
TU Berlin K27(Free Surface Tunnel)
Oxygen Saturation O2 = 58 %Nuclei concentration c =28.0 cm-3
Oxygen Saturation O2 = 34 %Nuclei concentration c =0.15 cm-3
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Time dependentHYKAT and K15Abubble concentrations c(20-230µm) with ship modelfor gassed and degassed02-saturations
Propeller loading KT = 0.29; Cavitation number σn= 2.0
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Propeller loading KT = 0.22; Cavitation number σn= 1.5
Time dependent HYKAT bubble concentrations c(20-230µm) with ship model for gassed and degassed 02-saturations
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Relative suction side cavitation occurrence from 20 revsfor two water qualities
in HYKAT at 10° starboard (left turning propeller)
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Conclusion
Free Surface Tunnel K27 (Berlin): High deaerating capacity
HYKAT (Hamburg): Typical nuclei concentration low → c ≈ 0.75 cm-3 (at 02 ≈ 0.80)
K15A (Potsdam): Higher nuclei concentration → c ≈ 1.0 to 3.0cm-3 (at 02 ≈ 0.60)
Suction side cavity extent of cp prop. in HYKAT (02 ≈ 0.80) and K15A (02 ≈ 0.60)
is about the same *)
Inclusion of O2- and nuclei content in scale effects considerations is difficult
due to water history, as well interaction betw. tunnel pressures and O2- content *) at fully developed cavitation