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On Cavitation Nuclei in Water Tunnels

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

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On Cavitation Nuclei in Water Tunnels

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  1. 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 University Rostock Hamburg University of Technology Consultant, Hamburg (TUHH)

  2. The Three Cavitation Tunnels Used

  3. Time Dependent Nuclei and Oxygen Content with Pressures in Berlin Tunnel K27 without Model

  4. 2D-Profile Cavitation Test in Berlin Tunnel K27 Speed VA = 5.5 m/s and angle of attack (α + α0) = 10°

  5. 2D-Profile in Berlin Tunnel K27 at VA = 5.5 m/s, cav-numberϬ = 2.0 andand angle of attack = 10°

  6. 2D-Profile in tunnels K15A and K27 at VA = 5.5 m/s, cav-numberϬ = 1.5 andand angle of attack = 10° TU Berlin K27 (Free Surface Tunnel) SVA Potsdam Tunnel K15A (Small Test Section) Oxygen Saturation O2 = 58 % Nucleiconcentration c =28.0 cm-3 Oxygen Saturation O2 = 34 % Nucleiconcentration c =0.15 cm-3

  7. Time dependentHYKAT and K15Abubble concentrations c(20-230µm) with ship modelfor gassed and degassed02-saturations Propeller loading KT = 0.29; Cavitation numberσn= 2.0

  8. Time dependent HYKAT bubble concentrations c(20-230µm) with ship model for gassed and degassed 02-saturations Propeller loading KT = 0.22; Cavitation numberσn= 1.5

  9. Relative suction side cavitation occurrence from 20 revsfor two water qualitiesin HYKAT at 10° starboard (left turning propeller)

  10. 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) • isabout 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

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