Friction Resistance of Ship. Chugoku Marine Paints, Nace Pusan Oct 2008

Size: px

Start display at page:

Download "Friction Resistance of Ship. Chugoku Marine Paints, Nace Pusan Oct 2008"

Job May
6 years ago
Views:

1 Friction Resistance of Ship

2 Drag for Ships Air Drag Form Drag Wave Drag Frictional Drag BC LNG Cont

3 Friction Drag Active Module to friction drag Micro bubble Polymer Riblet Elasticity modulus Contact angle Negative Module to friction drag Fouling Roughness

4 Roughness effect Fouling Macro fouling Slime Deterioration of surface Rusting Peeling of paint film Damage of the surface Maintenance work at Afloat under water cleaning Maintenance work at Dock Blasting Coating Blasting deduction of roughness Coating coverage of roughness / propagation of roughness dust spray, contamination

5 Hull surface condition

6 Roughness increase by fouling

7 Proper condition

8 Laminated layer of aged antifouling film may cause roughness by damage or peeling

9 Hull roughness by aging CR system by BSRA gauge 900 Hull roughness (μm) CR AF 50 ships Dry up F/B Dry up V/B Aft coat F/B Aft Coat V/B Average Hull roughness increases by aging. Huge roughness may be caused by peeling of the film Ships ages

10 Hull roughness by aging Long life AF by BSRA gauge Hull Roughness (μm) Long life AF 70 ships Dry up F/B Dry up V/B Aft coat F/B Aft Coat V/B Averge Ships ages Hull roughness increases by aging. Tar Epoxy Epoxy system is introduced, which may deduce the film damage and peeling off, and increment of roughness is much less than CR System

11 Hull roughness by aging Self polishing AF by BSRA gauge Hull roughness (μm) SPC-AF 40 ships Dry up F/B Dry up V/B Aft coat F/B Aft coat V/B Average Ships ages Hull roughness stabilized after 3 years. Tar Epoxy Epoxy system is introduced, which may deduce the film damage and peeling off. Self polishing mechanism may cover increment the roughness by damage??

12 Active Module Micro bubble Based on the test module, 10% reduction of friction resistance and 4% energy reduction is expected for the vessel 100m length /20m width /DLL 7m. Reduction of friction resistance and energy to form bubble is conflicting * Study started at the Japan Ship Research Association Polymer (Tom s effect) As huge amount of polymer are required, it is not utilized for marine m field. * found and developed by US Navy since 1940 th.

13 Active Module Riblet generate steady longitudinal vortex to control turbulent flow. The surface will be covered with contamination and effective life is limited. Surface profile like dimple Elasticity modulus Effect is not so clearly reported. Contact angle Effect is not so clearly reported.

14 Active Module Polymer effect the best elasticity modulus Surface chemical structure by hydrolysis contact angle relation between the contact angle (hydrophilic/hydrophobic mixture) and friction resistance Surface of paint film particle distribution of pigments structure of pigments structure of film

15 Measurement of friction resistance Comparison of drag owning to surface roughness Sand surface 2 Hydrolysis type AF at smooth surface 1 Si elastomeric AF at smooth surface

16 Drag Test Velocity 0.5m/sec Velocity 1.5m/sec

17 Drag test Panel 0.8m X 0.4m Condition of 0.5m/sec Measuring device

18 3-Dimension Analysis of Paint Film Surface Sand Surface Sand Surface Roughness of BSRA : 169 μm

19 3-Dimension Analysis of Paint Film Surface Hydrolysis type AF -A Silyl Acrylate with copper Roughness of BSRA : 43 micron

20 3-Dimension Analysis of Paint Film Surface Hydrolysis type AF-B Metallic Acrylate copper free Roughness of BSRA : 39 micron

21 3-Dimension Analysis of Paint Film Surface Si-A Foul release coating Roughness of BSRA : 32 micron

22 Friction resistance depend on the surface structure? Friction to flow rate B A Si-AFB Sand Surface D r a g (k g )Hydrolisis-AF BSRA Reduction of Friction μ 2m/sec Sand Surface 170 Hydrolysis-AF A 43 29% Hydrolysis-AF B 39 35% Si-AF B 34 34% flow ate(m/sec) AF-B and Si-B are almost same. AF-A is slightly large. The difference of water-repellent film and hydrophilic film was not acquired.

23 Roughness of the sample BSRA Ra Rz Pz Wz Correlation BSRA Ra Rz Pz Wz BSRA 1 Ra Rz Pz Wz

24 Friction to Surface Roughness The linear relation between friction resistance and surface roughness indicates. Friction Resistance to Surface Roughness measured by BSRA guage 0.14 Friction Resistance (Kg) Velocity 2.0m/s Velocity 1.8m/s Velocity 1.5m/s Velocity 1.0m/s Velocity 0.5m/s Surface Roughness (μm)

25 Conclusion Friction Resistance (1) Surface roughness is the dominant factor to deduce friction resistance more than 30%. (2) BSRA roughness and Friction resistance shows good collation. (3) BSRA Gage may represent Roughness, Profile and Wave (Rz, Pz, Wz). (4) Roughness of hull increases pursuant to age, but self-polishing effect may control the roughness increase. (5) Paint surface property works deduction of friction resistance, and the major cause might be surface roughness or profile. (6) The difference of water-repellent film and hydrophilic film was not acquired.

26 Thank you for your kind attention

27 Drag increase by slime attachment was reported by many references, as follows. Drag increase by bio-films. Understanding and prevention of drag increase due to marine fouling is as important as drag reduction. Schultz & Swain (1999) compared turbulent boundary layers on natural marine bio-films and a smooth plate. The average increases in Cf for slime film with mean thickness of 160μm and 350μm were 33% and 68%, respectively. Reference: Pro. Fred Stern et al.. The Resistance Committee Final Report and Recommendations to the 23 rd ITTC, page 27.

The challenge of supplying antifouling coatings to reduce emission of greenhouse gases

The challenge of supplying antifouling coatings to reduce emission of greenhouse gases Erik Risberg Jotun A/S Outline The complex technology situation Boundary layers and their influence on frictional