International Shipbuilding Progress - Volume 4, issue 36

Authors: van Manen, J.D.

Article Type: Research Article

Abstract: After a short introduction the present publication deals with the vortex system of the “screw + nozzle” propeller. The results obtained from systematic experiments with propellers in nozzles in which the length-diameter ratio of the nozzle, the number of blades and the blade-area ratio of the propeller have been varied are discussed. In addition the results of experiments carried out for determining the optimum diameter of the nozzle system behind the ship are described. Explanatory comments on nozzle design are given, including diagrams for determining the radial inequality of the axial velocities in the nozzle and for making computations …with regard to cavitation and strength. The influence of the clearance between blade tip and nozzle wall is discussed. Show more

DOI: 10.3233/ISP-1957-43601

Citation: International Shipbuilding Progress, vol. 4, no. 36, pp. 395-424, 1957

Authors: Blakeley, T.H. | Darling, R.F.

Article Type: Research Article

Abstract: The operating temperatures of gas turbines are dependent on the properties of the blade material. Since the advent of the jet engine, immense strides have been made in the improvement of metallic alloys and long-life gas turbines can now be designed to run at temperatures up to about 1,400° F, but this development is probably nearing its limit. In order to achieve a fuel economy comparable with that of a marine Diesel engine the operating temperature must be raised to something of the order of 2,200° F and this will clearly require cooling of the blades or alternatively the use …of non-metallic materials. The existence of high centrifugal stresses in rotor blades facilitates cooling by the thermosiphon principle and at the same time militates against the use of non-metallic materials which tend to be relatively weak in tension. The stator blades, however, offer a promising field for the application of non-metallic materials, and the present paper describes developments which have been carried out over the last eight years. Numerous materials were tested in the laboratory under conditions designed to simulate the stresses and thermal shocks that will be encountered in service. Various methods of manufacturing the required blade shapes were also investigated, and the shapes themselves were modified to some extent so as to meet the special requirements of the materials. Cascades of blades were tested in a high velocity gas stream at temperatures up to 2,200° F. Several materials were found to have reasonably good thermal shock resistance, and creep strength at high temperature appeared to be the most serious limitation. At least one material has emerged which seems likely to fulfil the necessary requirements. A single-stage turbine embodying refractory stator blades in conjunction with a liquid-cooled rotor is now in course of development. Show more

DOI: 10.3233/ISP-1957-43602

Citation: International Shipbuilding Progress, vol. 4, no. 36, pp. 425-435, 1957

Authors: van Manen, J.D.

Article Type: Research Article

DOI: 10.3233/ISP-1957-43603

Citation: International Shipbuilding Progress, vol. 4, no. 36, pp. 436-452, 1957