Patent GB-191507468-A (GB)
Title: Improvements in and relating to Turbine Installations for Ship Propulsion.
Inventor: PARSONS CHARLES ALGERNON
IPC: F01D15/02
Filed: 1915-05-18
Abstract: 7468. Parsons, Sir C. A., Walker, R. J., Cook, S. S., and Douglas, L. M. May 18. [Cognate Application, 16599/15.] Plant; driving and transmission mechanism, special application, of.-Relates to geared turbine installations for ship propulsion having two or more propeller shafts provided each with a group of two or more distinct turbine units, and consists in obviating the occurrence of idle propellers at reduced powers, when one or more units in each group are rendered inoperative, by arranging for at least one unit in each group to be in operation at all powers. For regulating the pressure drops and outputs of the various turbines, certain stages may be by-passed; where impulse stages are employed, the number of nozzle jets may be regulated for the same purpose. Those turbine units which remain in operation at low powers may be provided with a second set of transmission gearing which is put in operation at low powers and has a greater reduction ratio than that of the full power gearing of the same units. Four installations are shown by way of example in Figs. 1, 4, 8 and 9. In a twoshaft installation, Fig. 1. each shaft a<1>, a<2> is driven at full power by a set of independent high and low pressure turbines b<1>, c<1> and b<2>, c<2> connected in series and operating through gearing d. For low power, the units c<2>, b<1> are inoperative and disconnected, and steam is admitted by a conduit f<2> to the high-pressure unit b<2> and then by a conduit k to the low-pressure turbine c<1> coupled to the other shaft. In some cases, at low powers, the steam is admitted by an inlet to a cruising stage h in the highpressure unit b<2>. A separate cruising-turbine may be provided, driving through single or double reduction gearing. In another modification having a third propeller shaft provided also with high and low pressure units, the steam at low powers flows from the high-pressure turbine on the central shaft to the low-pressure turbines on the wing shafts. The turbines operating at low powers may drive through a second set of transmission gearing of greater reduction ratio than that used at high powers. These two sets of gearing d, s are shown in another installation, Fig. 8, which comprises three shafts a<1>, a<2>, a<3> each provided with a high, intermediate, and low pressure turbine b<1>, o<1>, c<1>, and b2, o<2>, c<2>, and b<3>, o<3>, c<3>, the second set of gearing s being arranged so that the high-pressure turbine b<3>, the intermediate-pressure turbine c<2>, and the low-pressure turbine c<1> can drive the propeller shafts at reduced powers. Suitable clutches e, z are provided. With the installation shown in Fig. 4, several power outputs can be obtained, high and low pressure turbine units b<1>, c<1>, b<2>, c<2>, b<3>, c<3> having additional initial stages a being provided on each shaft. By varying the cross connexions of the turbines and by adding or cutting out certain initial stages or high-pressure stages, or by regulating the number of nozzles in operation in the impulse stages, a large range of power outputs is obtained. In another modificatdon, Fig. 9, each propeller shaft has a high-pressure turbine b<1>, b<2>, b<3> and a low-pressure turbine c', c<2>, c<3> in operation at full power. At intermediate powers, steam is admitted by an inlet f<2> to the turbine b<2>, which operates in series with the turbine c<2>, as at full power, and steam is also admitted by an inlet f<3> to the turbine b<3>, which exhausts into the turbine c<1> on the other wing shaft. At low power, steam is admitted to the geared cruising- turbine t, which exhausts into the turbine b<3> and then into the turbine c<1>. In all the installations described, the inoperative turbines are disconnected by clutches. Specifications 3938/10, 20,082/14, and 20,366/14 are referred to.