Gaseous fluid vessel propulsion system

Abstract

A bow mounted gaseous fluid vessel propulsion system provides for the introduction of gaseous fluids, e.g. ambient air and / or exhaust fluid gas from the vessel's engine, into the enclosure or duct which houses or circumscribes the propeller. Air and other fluid gases are drawn down into the upper section of the enclosure or duct to allow the propeller to operate in a half submerged, or water surface-piercing condition, while the vessel is moving forward through the water. The beneficial effects of water surface-piercing propeller operation is thereby obtained within a self-contained unit which continually maintains the top of the propeller out of the water during normal forward vessel operation.

Description

BACKGROUND OF THE INVENTION[0001]Important benefits are realized by the utilization of bow mounted surface-piercing propeller systems, both on large displacement vessels such as ships and barges, and on more streamlined, lower displacement, high speed watercraft. Most significant of these benefits is the production of the self-producing, lubricating boundary layer of gaseous fluid, e.g. air and air bubbles created by the intermixing by the rotating bow propeller of water and air. This layer of gaseous bubbles, produced during forward vessel motion, travels over the bottom surface of the vessel, thus reducing frictional drag on the vessel's hull as it moves through the water. This significant benefit of bow mounted surface-piercing propellers, as well as others, are described in detail in U.S. Pat. No. 7,096,810, the relevant disclosure of which is incorporated by reference herein.[0002]It is accepted that vessel thrust and thus vessel efficiency will be increased by the use of a pro...

AI Technical Summary

Benefits of technology

[0004]The object of the present invention is to overcome the disadvantages and limitations of submerged, ducted propulsion systems by creating a water surface-piercing propeller environment within the duct, enclosure, or hull enclosure in which the propeller is operating; and further by effectively streamlining the duct in order to offset its detrimental drag effects, as it moves through the water. The result is an enclosed or ducted propulsion system which can propel vessels of any displacement at much higher speeds and with greater efficiency.

[0007]The “half-bullet” shape of the streamlined duct in several embodiments of the invention has a half-round shaped inlet. This may seem counter-productive when compared to the operation of a conventional ducted system which normally has a large, full circumference, aperture inlet for the large volume flow of water required to properly feed the shrouded propeller. However, the water flow in the duct of the present invention is accelerated through the inlet aperture of the open, forward lower section of the duct by the rotation of the propeller. As a result, the bow wave pressure is not redirected, but is sucked into this low pressure area of the duct, thereby relieving kinetic energy and contributing towards the increased efficiency of the propeller and ultimately in vessel performance.

[0009]Other objectives of the enclosed, water surface-piercing propeller of the invention are also achieved. For instance, given the flow of gaseous fluids, air and exhaust gas, at the intake of the propeller, there is complete propeller ventilation and a reduction of propeller cavitation at the intake. Friction on the entire propeller is also reduced. Thus, the invention provides a simplified method of addressing cavitation bubble effects, including gap cavitation, within a shrouded propeller.

[0010]The use of ambient air through the sealed housing of the drive shaft of the drive mechanism, in one of the embodiments of the invention, provides a more efficient and simplified way of supplying aeration to the duct, thereby providing the desired surface-piercing propeller effect within the duct.

[0011]The top half of the duct shown in several embodiments and the front portion of another embodiment of the present invention have bulbous bow type profiles. Such configurations have been proven to ameliorate bow wave pressure on a vessel and increase vessel performance up to 15%.

[0012]A further benefit of the present invention is the facilitating of engine exhaust venting through sealed air channels to substantially reduce the acoustic and thermal signatures of vessels. Exhaust noise suppression is also accomplished as a result of the aerated air / exhaust gas bubbles passing under the length of the bottom of the hull.

Problems solved by technology

This may seem counter-productive when compared to the operation of a conventional ducted system which normally has a large, full circumference, aperture inlet for the large volume flow of water required to properly feed the shrouded propeller.

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