함정용 소형 워터제트 개발에 관한 연구

Abstract

This paper describes development experience of a small water-jet propulsion system. In comparison with the general screw propeller of high speed vessle, the small water-jet propulsion has an advantage in side of cavitation performance. The development study of the small water-jet was progressed through an experiment. A design, a model test and a practical test run of the water-jet system came into action by the momentum flux theory of ITTC '96. This paper indicates a design procedure, an experiment procedure, an analysis of model test, a self propulsion test and the practical test run. The maximum output is limited to 1800rpm for a fuel reduction in case of an existing installed engine. Thus, the design purpose of this study is to adapt an impeller for characteristics of the engine and to extend a nozzle parallel part.

The new impeller was designed through study on 'angle of attack' of the impeller getting into streamline and a shape and size of the nozzle was decided by a CFD flow analysis. This paper is study on the correlation between the water-jet system to a hull in a trial running progress, effect of inflow flow rate in a inlet duct, a loss coefficient of the water-jet system, effect of ship's running angle by trim tap and performance of the water-jet system with respect to nozzle size.

Performance prediction by momentum flux theory of ITTC '96 is almost similar to sea trial result within the margin of 10% error. An important thing of a small water-jet system performance is comparison of nozzle size, pump diameter and diameter ratio inlet duct, and to out of range of cavitation boundary. The unloading technique(the technique has an effect to increase of chord length and blade area and decrease of the pitch angle) applied to the redesign of an impeller has an effect to increase of ship`s speed. Nozzle diameter of a design stage was 347 mm, but final applied diameter is 362 mm. This paper fully expect to contribute to resolving problems occurring in the development of waterjet propulsion system and sea trial trouble shutting processing.