International Shipbuilding Progress - Volume 3, issue 27

Authors: Tachmindji, A.J.

Article Type: Research Article

Abstract: The potential problem is solved for the circulation distribution of an optimum propeller with a finite number of blades and a hub of constant diameter. The effect of the hub has been calculated for specific cases, showing that it becomes important for propellers with large hub diameters and small number of blades and increases with increasing pitch.

DOI: 10.3233/ISP-1956-32701

Citation: International Shipbuilding Progress, vol. 3, no. 27, pp. 563-572, 1956

Authors: Lap, A.J.W.

Article Type: Research Article

Abstract: The only method of deriving resistance formulae for turbulent flow along flat plates more or less theoretically is by starting from theoretical formulae for pipe flow. The latter formulae are, therefore, subjected to a detailed consideration as is also done with the assumption that these formulae may be used in the boundary layer of a flat plate. A new approximate method is developed to establish a relation between resistance coefficients for pipes and rectangular flat plates. This method proves to be in fair agreement with Schultz-Grunow’s measurements of local frictional resistance. With the aid of theoretical formulae the total …frictional resistance coefficients can be determined from the local frictional resistance coefficients. Apart from this the total frictional resistance coefficients can also be derived from resistance experiments with flat plates. The agreement between the two methods is highly satisfactory. With the aid of results obtained from experiments with model families it is shown that it is not satisfactory to apply plate-friction coefficients to ship forms. A new method is indicated for calculating frictional resistance coefficients for ship forms. It appears that frictional resistance coefficients of pipes, plates (local and total) and ship forms can be represented by the general formula: χ 2 ζ = l n R e ζ A n + C where: χ = universal constant = 0.4144 ; log A 0 = 0.000 for pips; log A 1 = 1.556 for local frictional resistance coefficients of flat plates; log A 2 = 1.980 for total frictional resistance coefficients of flat plates; log A 3 = 2.10 − 2.50 for ship forms . Values frequently occurring for ship forms are log A 3 = 2.35 − 2.40 . Show more

DOI: 10.3233/ISP-1956-32702

Citation: International Shipbuilding Progress, vol. 3, no. 27, pp. 573-587, 1956

Authors: Kumai, Toyoji

Article Type: Research Article

DOI: 10.3233/ISP-1956-32703

Citation: International Shipbuilding Progress, vol. 3, no. 27, pp. 588-590, 1956

Authors: Dorey, S.F.

Article Type: Research Article

Abstract: Andrew Laing was privileged to see the remarkable developments in marine engineering which were facilitated by the introduction of processes for the quantity production of high quality carbon steel components. Plain carbon steels continue to predominate other structural materials in this marine field. Nevertheless, during the twenty-five years which have elapsed since his death, new fabrication and treatment processes and many alloy steels have been employed to simplify production and overcome adverse service conditions. More recently special high duty cast irons have also assisted in these respects. This lecture deals with a number of these aspects and where possible …both cause and effect are considered. In addition, some future trends and developments are also indicated. Show more

DOI: 10.3233/ISP-1956-32704

Citation: International Shipbuilding Progress, vol. 3, no. 27, pp. 591-609, 1956