International Shipbuilding Progress - Volume 9, issue 89

Authors: Tsakonas, S. | Breslin, J.P.

Article Type: Research Article

Abstract: Expressions for the vibratory pressure field produced by an operating counterrotating propeller system are developed in terms of first and second blade harmonics of the individual propellers. It is found that the pressure signal due to a counterrotating propeller can be obtained from the summation of the pressure fields of its two components as though the two propellers operate as separate units, since their mutual interference has been found to contribute little to the total vibratory pressure signal in the near field. This study indicates that the counterrotating propeller system has vibratory characteristics much superior to an equivalent single propeller …having the number of blades of one of its components, delivering the same thrust at the same RPM at optimum conditions. A study of the interference effects by means of a two-dimensional analogue indicates that the effect of the forward propeller on the aft is much greater than the effect of the aft propeller on the forward propeller. Show more

DOI: 10.3233/ISP-1962-98901

Citation: International Shipbuilding Progress, vol. 9, no. 89, pp. 3-19, 1962

Authors: Brown, T.W.F.

Article Type: Research Article

Abstract: The paper is in three parts: the introduction, including some early history of hydraulic transmissions; the second section dealing with experimental work in the development of the elements of the hydraulic transmission; and the third section giving results in service in the Shell tanker Auris , followed by general conclusions. The Pametrada hydraulic transmission enables a ship to be driven ahead or astern by means of a uni-directional turbine in conjunction with a gear-box. The primary elements of the ahead and astern couplings are mounted on a quill shaft driven by the turbine, and the secondary or output elements …are bolted to the primary pinion of the gear-box. Manoeuvring is effected simply by admitting oil to the ahead or astern coupling as required. The ahead coupling also incorporates a hydraulically-operated friction clutch which is engaged once the ship is at sea and thus avoids the losses due to slip in the coupling. Following several years of research and experiment, the Pametrada hydraulic transmission was fitted in the gasturbine tanker, Auris , where it was conspicuously successful and enabled the ship to manoeuvre with great facility. The present paper, after reviewing the early history of the transmission, describes in detail the research which was carried out and the experience gained in the Auris . The conclusion is reached that although this transmission was originally developed with the gas-turbine application mainly in mind, it also offers great advantages in conjunction with steam turbines where the simplification resulting from the elimination of the astern turbine, manoeuvring valves, piping, etc. would simplify design problems and enable higher steam conditions to be employed. Show more

DOI: 10.3233/ISP-1962-98902

Citation: International Shipbuilding Progress, vol. 9, no. 89, pp. 20-26, 1962

Authors: Andvig, T.A.

Article Type: Research Article

DOI: 10.3233/ISP-1962-98903

Citation: International Shipbuilding Progress, vol. 9, no. 89, pp. 27-33, 1962

Authors: Cleff, P.H.

Article Type: Research Article

DOI: 10.3233/ISP-1962-98904

Citation: International Shipbuilding Progress, vol. 9, no. 89, pp. 34-48, 1962