A method for calculating the ship friction resistance based on the Zazurca's proposal was developed. The proposal deals mainly with a simple transformation of the actual ship form into a body of revolution for which characteristics of the potential flow and the boundary layer were calculated. Algorithms and computer programs were elaborated. Based on these programs systematic calculations were performed of the ship frictional resistance for about eighty ship forms for which results of model resistance tests were available. The ship forms used embrace a wide range of fullness. Calculations showed evidences of boundary layer separation, viz. for some forms of larger fullness the velocity of the potential flow and the shear stress reached the zero value at some distance from the railing edge. The distance changed in a systematic way with the ship form parameters. The method of friction resistance calculation was verified for a single case using experimental results for four geometrically similar models of the series 60 as published by Conn and Ferguson. The comparison showed a satisfactory agreement between the calculated and measured values of the friction resistance components. The calculated friction resistance of all the ship forms analysed was then compared with the viscous resistance of the forms obtained from the tank tests for the non-wave-making Froude number range. The excess of the viscous resistance over the friction resistance calculated was assumed to be the viscous pressure resistance. In this way the viscous resistance was split into the friction and pressure components. Both components found for all the models of the sample of forms collected were then analyzed by means of the regression analysis. The statistical generalization was proposed giving relation between the friction resistance, viscous pressure resistance, boundary layer separation length and the ship form parameter.
Investigation of the ship viscous resistance components and their dependence on the hull form parameters based on the body of revolution analogy
Untersuchung der Komponenten des Zähigkeitswiderstandes eines Schiffes und ihre Abhängigkeit von den Rumpfformparametern auf der Basis der Analogie zum axialsymmetrischen Körper
Prace Inst. maszyn przeplywowych ; 89 ; 87-105
1989
19 Seiten, 10 Bilder, 5 Tabellen, 16 Quellen
Article (Journal)
English
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