AU663119B2

AU663119B2 - Wave making energy absorber during vessel's propulsion

Info

Publication number: AU663119B2
Application number: AU27099/92A
Authority: AU
Inventors: Emmanuel E. Petromanolakis
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-19
Filing date: 1992-10-19
Publication date: 1995-09-28
Anticipated expiration: 2012-10-19
Also published as: AU2709992A

Description

I _CI 663119

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "Wave making energy absorber during vessel's propulsion" The following statement is a full description of this invention, including the best method of performing it known to me: ~-111~ -1-

DESCRIPTION

Wave making_energy_absorber duringvessel's ro2ulsion.

TECHNICAL FIELD The invention refers to the hydrodynamic field and it concerns, the installation of an external conductor called absorber, placed forward of the bow of a vessel, extending aft of the bow too, either as a single conductor or divided in two parts if necessary.

S.THE PRIOR ART The state of the art faces the propulsion problem of a vessel, in order to decrease partially the wave making energy losses, by installing a bolbous bow at forward end, or a conductor or conductors' system inside the vessel which starts from the bow and ends at the sides or at the aft end of a vessel. However this entails a significant increase of friction losses due to the large length of the conductor, and the decreasing displacement, due to the conductor's volume, in the case where the conductors run along the entire length of the vessel. Consequently the prorulsion power per cubic meter of displacement or transported volume (HP/cubic meter) is increased, that is we are going to have less transported capacity for the same power, which is equivalent to increased -2fuel oil and lubricants consumption for the same transported cargo capacity.

However, the bulbous bow also decreases the wave making resistance but the decrease attained thereby is comparatively less than the decrease attained by the proposed wave making energy absorber arrangement.

Consequently the state of the art practically is not so economical in comparison to the proposed invention.

Into this invention, vessel's displacement is kept unchanged having a better hull efficiency, due to the decrease of propulsion resistance by installing a wave o making energy absorber. The obtained efficiency being much larger than the efficiency obtained in the prior art, in the abovementioned manner, the present I o° .invention provides a substantial decrease of the wave making resistance.

SUMMARY OF THE INVENTION According to the invention there is provided a wave energy absorbing device for water borne vessels including means mounted forward of the bow of a water borne vessel comprising an external conductor with at least one inlet opening joined to at least one outlet opening by a passage for the flow of water therethrough, at least a part of said external P conductor being located below the vessel's water line level, whereby the water traversing through said external conductor as said vessel is propelled through said water effects a reduction of any wave making energy losses of the vessel.

ii i I -2a- BRIEF DESCRIPTION OF THE DRAWINGS The invention will be made clearly apparent to those skilled in the art by reference to the accompanying drawings, wherein are depicted illustrative views of the invention.

Figure 1 shows in accordance to a first embodiment of the invention a side view of the vessel at the bow of which is installed the proposed conductor-wave making energy absorber.

Figure 2 shows a plan view or section A-A of figure 1.

Figure 3 shows a front view or section B-B of figure 1.

4 4.

4 qTLj I L i L- I _I r": 1 Figure 4 shows in accordance to an alternative embodiment of the invention a side view of the vessel, at the bow of which is installed the proposed conductor wave making energy absorber divided at the bow to a pair of legs extending on either side of the vessel.

Figure 5 shows a plan view or section C-C of figure 4.

Figure 6 shows a front view or section D-D of figure 4.

The various points illustrated in the accompanying drawings are enlisted below in an order corresponding to their reference numerals in the accompanying drawings.

1. Vessel or hull.

2. External conductor-wave making energy absorber placed forward of the bow 3. Supporting- and reinforcing elements.

4. Legs of conductor 2 extending on either side of the bow.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the attached drawings,the invention will be described in an illustrative manner. According to the first embodiment of the invention an external conductor is mounted forward of the bow on a vessel, extending below or below and above the water line of the vessel. This conductor wave making energy absorber has a certain length in order to accomplish the aim of the invention, that is to extingnish or reduce the wave making energy losses. When the sea water -4enters through at least one or more inlet openings and is discharged through at least one or more outlet openings the vessel's wave making is reduced.

The manner in which the invention is implemented is presented in Figures 1-3, wherein are shown a side view, a section A-A and a section B-B. The side view also shows the height of this external conductor wave making energy absorber 2, and the distance of the conductor from the external side of a vessel 1.

This conductor-wave making energy absorber extends in accordance to an alternative embodiment of the invention aft of the bow,being divided in at least two legs with one outlet opening on each of those legs.

In accordance.to a further alternative embodiment of the invention, it is possible to ommit the conductor extending forward of the legs, so that sea water enters directly into oo"' at least one of the legs extending on either side of the vessel and is discharged through at least one outlet opening.

Therefore,the energy lost,due to the wave making during the propulsion of the vessel in sea water,is absorbed and thereby reduced. Consequently,less power is required for the same displacement of the vessel, and transportation of a cargo volume unit is thereby made cheaper.

Conductor supporting elements 3, support this external conductor 2 on the hull 1, the conductor itself and/or legs 4 extending on either side have hydrodynamic shape to obtain the best possible efficiency of this arrangement.

I h111111111111M In this way, we are going to have a wave making decrease which being absorbed as abovementioned results in a more economic transportation, because due to the wave making decrease we shall have a decrease of the total rPsistance during vessel's propulsion, which is equivalent to the propulsion power corresponding decrease and finally a fuel oil and lubricants decrease for the same displacement and speed.

The size and hydrodynamic shape (if required) of the conductor as well as the hydrodynamic shape of the supporting elements, the distance from the center line of this external conductor-wave making absorber depends on vessel's size, design or cruise speed and displacement.

It must hereby be noted that e'ther the single conductor 2 or the conductor 2 divided into two legs 4 or even simply the two legs 4, right from the inlet opening to the outlet opening or openings, may have any desired linear or curved shape and may either be of a perimetrically compact structure or it may include partial openings, e.g. in its vertically defined upper and/or lower sides. Openings and/or slots and/or grooves of a desired number,form and arrangement, by means of which a balancing of pressures is obtained, may also be provided at the flow region between the inlet opening or openings up to the outlet opening or openings.

It must also be noted that, in accordance to an illustrative embodiment of the invention, a portion of either a -k I I -6wave makinc; energy absorber 2 mounted forward of the bow and/or the abovementioned bow's aft extending legs 4 may be incorporated into the hull, thereby suitably modifying bow's geometry,whilst it is also possible that the conductor or legs are mounted on the hull in combination to the existing technology of bow's bulb.

All the abovementioned facts are naturally valid both with vertical bow vessels as well as vessels with a bow inclined at any desired inclination. It is understandable too that, the proposed arrangement, concerning the advantageous mounting of the wave making energy absorber, is equal lly valid with vessel the vessel being either fully or partially loaded and independently of the ballast condition.

The invention can be implemented at any desirable form design or size.

The figures (drawings), being attached to the present description, do not constitute a confining form of the invention, but simply an illustrative one.

Any other modification that does not constitute a new inventive step and does not contain elements of a new invention does not restrict the rights claimed in the present invention.

The construction of the invention is being realised by profile iron and steel plates or other desired properly shaped materials.

Their dimensions depend proportionally on the ship's dimensions and design or cruise speed, being desired.

-7- By the term "conductor" is meant not only the one of a circular section but that of any section transversally and longitudinally, the section being either constant or convergent or divergent section or a combination of two or more sections.

The proposed inventions effects an absorbing of the energy losses due to wave-making.

By the term "supports" are meant steel constructed or other material pieces, which are being used as supports of the said bow's -external or partialy incorporated in the hull conductor, these supports being hydrodynamically shaped or not.

'1o

I

Claims

1. A wave energy absorbing device for water borne vessels including means mounted forward of the bow of a water borne vessel comprising an external conductor with at least one inlet opening joined to at least one outlet opening by a passage for the flow of water therethrough, at least a part of said external conductor being located below the vessel's water line level, whereby the water traversing through said external conductor as said vessel is propelled through said water effects a reduction of any wave making energy losses of the vessel.

2. A wave energy absorbing device as claimed in claim 1, wherein said external conductor extends aft of the S 15 bow line, said external conductor being divided into at least two legs, each said leg having at least one inlet and at least one outlet opening for water flow.

3. A wave energy absorbing device as claimed in a'v one of claims 1,2, wherein said external conductor or said at least two legs have a constant, divergent or convergent section, or a combination of two or more such sections in part therealong.

4. A wave energy absorbing device as claimed in any one of claims 2-3, including at least two said legs extending longitudinally aft of the bow line, wherein each of said legs includes at least one outlet opening for water flow, said water flow being directly introduced into said at least two legs, extending on either side of the bow.

A wave energy absorbing device as claimed in any one of claims 1-4, wherein said external conductor has rr a hydrodynamic shape in the longitudinal direction -9- along at least a portion of the length thereof.

6. A wave energy absorbing device as claimed in any one of claims 1-5, wherein said passage comprises openings, slots, or guide ribs of a desired number, form and arrangement, whereby said openings, slots or guide ribs effect a balancing of pressures upon said device.

7. A wave energy absorbing device as claimed in any one of claims 1-6, wherein a portion of said external conductor mounted forward of said bow or of said legs extending aft of said bow is incorporated into the vessel, thereby shaping the geometry of the bow.

8. A wave energy absorbing device as claimed in any one of claims 1-7, wherein said absorbing device is mounted on a vessel in combination with a bulbous bow.

9. A wave energy absorbing device as claimed in any one of claims 1-8, wherein said passage is of a linear or a curved shape and is a perimetrically compact structure throughout its length. 1

10. A wave energy absorbing device as claimed in any one of claims 1-9, wherein said passage has a linear or curved shape, and is entirely or partially opened on either of its vertically defined upper or lower 30 sides.

11. A wave energy absorbing device as claimed in any one of claims 1-10, wherein the bow line of the vessel upon which said wave energy absorbing device is mounted is either parallel to or inclined with respect to the natural vertical line, said line being determined with the vessel at rest in calm conditions. T '3 1J BeLU

12. A wave energy absorbing device as claimed in any one of claims 1-11, wherein said external conductor is mounted to the vessel by means of supporting elements which are shaped with or without hydrodynamic shaping, said shaping being determined with reference to the direction of water flow therepast.

13. A wave energy absorbing device as claimed in any one of claims 1-12 wherein said external conductor is located wholly below said water line level.

14. A wave energy absorbing device as claimed in any one of claims 1-12 wherein said external conductor is located astride said water line level.

15. A wave of energy absorbing device substantially as hereinbefore described with reference to Figure 1-3, or Figures 4-6 of the accompanying drawings. D]hTED this 18th day of July 1995 S" EMMANUEL E. PETROMANOLAKIS Patent Attorneys for the applicant HALFORD CO *a 0 >J e- iiiii Cli. i -11- ABSTRACT The invention is concerned with the installation of a wave making energy absorber or external conductor placed forward of the bow of a vessel The absorber may extend aft of the bow if necessary. The absorber extends below or below and above the water level, taking into consideration the full load and ballast condition of a vessel The absorber which may have aft of the bow extending legs is symmetrically constructed. The legs may be of constant, divergent or convergent section or any combination of the above-mentioned sections. ,1 C I