Marine propulsion – Jet drive – Direction control for fluid jet
Reexamination Certificate
1999-09-07
2001-01-09
Sotelo, Jesus D. (Department: 3617)
Marine propulsion
Jet drive
Direction control for fluid jet
C440S038000, C060S222000, C114S163000
Reexamination Certificate
active
06171159
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION
The present invention relates to waterjet propulsion, more particularly to the steering and reversing of waterjet propulsion systems for marine vessels such as ships.
Marine waterjet propulsion has increasingly gained acceptance in recent years, and has begun to challenge the long-established dominance of screw propellers. A waterjet-propelled craft is known to be capable of affording a superior maneuvering capability.
In fact, waterjet propulsion offers several advantages over conventional screw propellers, including the following: simplification of mechanical arrangement by eliminating reverse gears, a complicated mechanical device to change propeller pitch, and long propulsion shafting; flexibility of machinery arrangement and placement of machinery in the hull; improved maneuverability, especially the ability to turn at zero forward speed; and, elimination of external rudders, shafting and propellers, thereby improving shallow water operation.
However, several disadvantages are known to be associated with existing waterjet craft, which conventionally effectuate jet discharge in the air. A significant disadvantage is low propulsive efficiency at speeds less than about 25 knots. As a consequence, existing waterjets have been principally applied to high speed vessels at speeds between approximately 35 to 70 knots. Such waterjet designs suffer from poor performance at off-design speeds.
Peterson et al. U.S. Pat. No. 5,476,401 issued Dec. 19 1995, incorporated herein by reference, and Dai et al. U.S. Pat. No. 5,439,402 issued Aug. 8, 1995, incorporated herein by reference, disclose improvements pertaining to a conventionally abovewater waterjet system insofar as providing good hydrodynamic performance (e.g., high propulsive efficiency and good cavitation performance) both at low speeds and at high speeds.
The present invention is especially motivated by the need, discerned by the present inventors, to successfully effectuate waterjet propulsion underwater (into a water medium)—rather than abovewater (into an air medium), as is conventionally done. Jets on existing waterjet craft are typically discharged into the air. The present inventors recognize the benefits which a naval ship or commercial ship could enjoy by circumventing certain problems normally associated with waterjet discharge into the air. Notably, discharging the jets underwater would eliminate the resultant noise from the jets plunging into the sea, and would increase propulsive efficiency.
Nevertheless, conventional steering and backing systems for waterjet craft are effective for the familiar abovewater mode of jet discharge, but would be unsuitable for the unfamiliar underwater mode of jet discharge. Conventional waterjet steering/backing systems include outlet nozzles for receiving the accelerated flow from the pumps and discharging the jets in a rearward direction above the waterline. The steering/backing of the craft is typically accomplished by deflecting the jets using rotating steering sleeves or buckets. Hence, according to common practice, steering and backing systems use rotating sleeves to vector the jets for maneuvering. These types of devices would experience severe drag penalties in water. Moreover, the bulky sleeves would trigger severe cavitation.
Therefore, there is a need for a waterjet steering/backing system which is suitable for a waterjet craft having one or more jets discharged underwater.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a steering and reversing system for a waterjet-propelled craft.
It is another object of the present invention to provide a steering and reversing system for a waterjet-propelled craft wherein a jet, or a plurality of jets, are discharged underwater.
A further object of the present invention is to provide, for an underwater-discharge waterjet-propelled craft, a steering and reversing system which is characterized by efficiency in terms of steering and maneuvering capability.
Another object of the present invention is to provide, for an underwater-discharge waterjet-propelled craft, a steering and reversing system which is relatively uncomplicated and economical.
The present invention provides a relatively simple waterjet steering system which is characterized by efficient capabilities in terms of steering and maneuvering. In particular, the present invention advantageously affords minimum drag and cavitation-free operation in straight course and during course-keeping maneuvering.
In accordance with typical embodiments of the present invention, a waterjet exit assembly comprises an upper horizontal wall, a lower horizontal wall and a plurality of approximately equidistantly spaced vertical walls. The upper horizontal wall, the lower horizontal wall and the vertical walls form a plurality of adjacent channels for the waterjet. The waterjet exit assembly also comprises a plurality of horizontally pivotable vertical flaps, wherein each vertical wall includes a vertical flap. Each vertical flap is capable of deflecting to selected dispositions with respect to its corresponding vertical wall.
According to typical inventive practice, the vertical walls include two lateral vertical walls and at least one medial vertical wall. Each medial vertical wall includes a vertical flap which is a divisible vertical flap, which is divisible into two horizontally pivotable demiflaps. Each demiflap is capable of deflecting to selected dispositions with respect to its corresponding medial vertical wall. Many inventive embodiments are characterized by two channels, three vertical walls and three flaps.
Generally, the present invention is implemented in association with waterjet means characterized by the capability of accelerating water and discharging the accelerated water in a manner suitable or adaptable for propelling a marine vessel. According to typical inventive practice, the waterjet means will comprise a water-accelerative mechanism of a kind which includes at least one pump; nevertheless, the present invention can be used in association with any kind of waterjet means having the requisite capability.
According to frequent practice of this invention, water is introduced into two adjacent waterjet pumps, and exits via two respective accelerated flow discharge nozzles. The accelerated flow is then controlled by the inventive steering-and-backing apparatus, which includes two adjacent flow-straightening chambers. Each flow-straightening chamber includes its own sidewall flap. Also, both flow-straightening chambers share a longitudinally divisible (splitable) medial sidewall flap. The three sidewall flaps are used for jet direction vectoring, thereby effectuating steering.
Depending on the inventive embodiment, backing is effectuated according to either of two inventive methodologies. According to some inventive embodiments, a set of rotating buckets is implemented in the transom stern for flow reversing. According to other inventive embodiments, bottom wall flaps are implemented for flow reversing; each flow-straightening chamber includes a bottom wall flap. Some inventive embodiments can be provided, in the alternative, with both flow reversing capabilities.
Featured by this invention is the provision of sidewall flaps which serve to vector the jet direction for steering and maneuvering. The sidewall flaps are parts of the dual flow-straightening exit chamber assembly. The two lateral sidewall flaps are each a part of one such flow exit chamber, while the single medial sidewall flap is shared by both flow exit chambers and is capable of splitting into two medial semi-flaps. Each lateral sidewall flap is embedded in a lateral sidewall. The medial sidewall flap is embedded in the medial sidewall.
Sidewall flap deflection is inventively effectuated without leading e
Gowing Scott
Peterson Frank B.
Shen Young T.
Kaiser Howard
Sotelo Jesus D.
The United States of America as represented by the Secretary of
LandOfFree
Steering and backing systems for waterjet craft with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Steering and backing systems for waterjet craft with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Steering and backing systems for waterjet craft with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2476572