SHIP MOTION WHEN BLOWING AIR UNDER ITS BOTTOM

Theoretical and experimental investigations of the reduction of a ships frictional resistance by means of blowing air under its bottom were carried out. Calculations performed according to formulas developed by K. Fedyayevskiy (Reduction of friction resistance by changing the density of the liquid near the wall-Promyshlennaya aerodinamika, vyp. 24, 1962) for a similarity criterion of model and full scale tests and the coefficient of friction of a streamlined wall revealed the possibility of greatly reducing friction by changing the physical properties of the liquid. This became possible through progress in the field of artifical cavitation by considering the air layers as artificial cavities. The calculated results were compared with experimental data derived from model and full-scale tests of a 3000 t and 84.6 m long barge with a 55.8 m long cylindrical middle section which was air lubricated along its entire length. Model tests performed for various variants at 1.4 m/sec, which corresponds to 16 km/hr for a full size barge, revealed a 20 percent (at a 0.16 m draught) or 17 percent (at a 0.32 m draught) reduction in the towing resistance with air lubrication. Full scale tests were performed in the shipyard and on the Kuybyshev reservoir with the pusher-tug Dynayskiy; they included the control of air delivery and distribution under the barge bottom, measurement of the speed and resistance of the barge, and measuring the pusher engine operation parameters when moving with and without air lubrication. A comparison of the calculated and experimental data shows that the gain in resistance with air lubrication and pushing at 16--18 km/hr was 23--26 percent; the power gain of the pusher-tug diesel engine was nearly 20 percent at 16 km/hr. The analysis of the full scale tests revealed a 60 percent decrease in resistance with air lubrication of the flat bottom section.

• Authors:
  • Basin, A M
  • Butuzov, A A
  • Ivanov, A N
  • Olenin, YuL
  • Petrov, V I
  • Potapov, O F
  • Ratner, YeR
  • Starobinskiy, V B
  • Eller, A O
• Publication Date: 1968

Media Info

• Pagination: p. 3-8
• Serial:
  • Sudostroyeniye (Soviet Shipbuilding) [USSR]
  • Issue Number: 1

Subject/Index Terms

• TRT Terms: Drag; Fluid resistance; Friction; Hulls; Lubrication; Propulsion; Skin resistance; Tests
• Uncontrolled Terms: Hull resistance
• Old TRIS Terms: Air lubrication; Drag reduction; Friction reduction; Propulsion tests
• Subject Areas: Design; Marine Transportation;

Filing Info

• Accession Number: 00014935
• Record Type: Publication
• Source Agency: Joint Publications Research Service
• Files: TRIS
• Created Date: May 7 1971 12:00AM