International Shipbuilding Progress - Volume 18, issue 198

Authors: van Manen, J.D.

Article Type: Editorial

DOI: 10.3233/ISP-1971-1819801

Citation: International Shipbuilding Progress, vol. 18, no. 198, pp. 31-31, 1971

Authors: Oosterveld, M.W.C.

Article Type: Research Article

Abstract: This paper presents the results of open-water tests with different propeller types (the Wageningen B-screw series, ducted propeller series with nozzles of both the flow accelerating and decelerating type and contra-rotating propeller series). A discussion of the fairing of the results of such tests by means of a regression analysis is given. For systematic screw series, for instance, the thrust and torque will in future be given in the form of polynomials of the advance coefficient, pitch ratio, blade-area ratio and number of blades. The effect of the Reynolds number (scale effect) will also be taken into account in these …polynomials. For the ducted propeller series and the contra-rotating propeller series the thrust and torque will be given in the form of polynomials of the advance coefficient and pitch ratio. The derived polynomials enable design calculations and analysis to be done with a computer in an easy way. Finally some special applications of ducted propellers and contra-rotating propellers are discussed. In the case of ducted propellers attention is paid to nonaxisymmetrical nozzle shapes which mayi be attractive for minimizing problems relating to propeller induced vibrations and cavitation in single-screw ships (tankers) and twin-screw ships (fast naval ships). Finally, the specific field of application of contra-rotating propellers and of the overlapping twin-screw stern arrangement is discussed. Show more

DOI: 10.3233/ISP-1971-1819802

Citation: International Shipbuilding Progress, vol. 18, no. 198, pp. 32-55, 1971

Authors: van der Meulen, J.H.J.

Article Type: Research Article

Abstract: A four-bladed propeller model has been tested in a water tunnel with flow regulator. Cavitation erosion of the aluminium alloy blades was caused by simulating the wake pattern behind a single screw ship in the test section of the tunnel. The relationship between the rate of weight loss and the time of exposure to cavitation was measured for each blade individually. Comparative tests, using the same material, have been carried out in a rotating disk apparatus and a magnetostriction oscillator. The erosion rates of the propeller model and of the specimens tested in the rotating disk apparatus show a similar …dependence on time during the incubation, acceleration and deceleration period. A steady state period does not occur. The erosion rates of the specimens tested in the magnetostriction oscillator show a considerably different dependence on time. The mean erosion intensity of the test devices is 2.5–3 times larger than with the propeller model, based on the actual time of exposure to cavitation. Show more

DOI: 10.3233/ISP-1971-1819803

Citation: International Shipbuilding Progress, vol. 18, no. 198, pp. 56-66, 1971

Authors: Bosman, L. | Haanstra, J.

Article Type: Research Article

Abstract: A brief review is given of the copper-based casting alloys, suitable for the manufacture of ship’s propellers. Some specific properties of these alloys are illustrated. The moulding, melting and casting techniques employed in the production of high-quality propellers must satisfy stringent requirements and a well-considered practical application of a thorough theoretical knowledge of the solidification process is necessary. Attention is called to the cavitation-erosion-corrosion resistance of the copper-based propeller alloys. Some basic factors relating to the Smith diagram are put forward. Finally, some important indications are given concerning propeller repair.

DOI: 10.3233/ISP-1971-1819804

Citation: International Shipbuilding Progress, vol. 18, no. 198, pp. 67-79, 1971

Authors: Wind, J.

Article Type: Research Article

Abstract: A controllable pitch propeller has a central huh which serves not only for the attachment of the blades but also contains the mechanical components to make the blades rotate. Ins i de the hub a translation motion is transformed into rotation of the blades. This involves large actuating forces sometimes amounting to three times the total thrust on the propeller. Various types of blade suspension systems are described. The principles of crank-conrod, crank-slot, slot-pin and double-acting mechanisms are discussed in relation to their historical origin and development to modern conceptions. It is concluded that a sliding slot mechanism with …slots in the rotating parts has favourable characteristics for application in normal and feathering propellers . Show more

DOI: 10.3233/ISP-1971-1819805

Citation: International Shipbuilding Progress, vol. 18, no. 198, pp. 80-94, 1971