AIRBOAT NOISE REDUCTION AND IMPELLER DESIGN FOR WATER JET PROPULSION SYSTEMS
HYDRONAUTICS INC LAUREL MD
Pagination or Media Count:
The report deals with problems encountered in two different forms of propulsion used for shallow draft boats. The first part of the report describes the program undertaken to reduce the radiated noise levels around a boat propelled by means of an airscrew. A new propeller was designed to reduce the radiated noise while providing the same or higher thrust. A shroud was designed to reduce the propeller thrust loading and hence decrease the radiated noise level. An extensive series of noise and thrust performance tests was carried out, in which the number of blades and blade pitch were varied. The results of these tests indicated that the new propeller with 4 blades and a 14-degree pitch, operating in the shroud provided more thrust and was quieter than the original wooden propeller. The second part of the report concerns the design of impellers for use in water jet propulsion system for shallow draft boats. The impellers in a commercial water jet system used by the Army did not perform as anticipated. The report describes the design of a new impeller and guide vanes to replace those in the commercial unit.
- Marine Engineering