JPS60163784A - Ship with air exhaust nozzles at bottom - Google Patents

Abstract

PURPOSE:To reduce the hull friction resistance by jetting compressed air through multiple exhaust nozzles provided on the ship's bottom and forming an air layer between the ship's bottom and water. CONSTITUTION:Air with a pressure higher than the water pressure at the ship's bottom section is jetted through multiple air exhaust nozzles 3 provided on the ship's bottom 2, and an air layer or a mixed layer of air and water is formed between the ship's bottom 2 and water. Accordingly, the friction resistance caused by the navigation of the ship can be effectively reduced without being limited by the size of the ship and the height of waves.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a ship that reduces the frictional resistance of the ship's hull by providing an air outlet in the ship's bottom to create an air layer between the ship's bottom and water.

[Prior art]

Ship resistance consists of wave resistance, eddy resistance, frictional resistance, and air resistance.

Wave resistance and eddy resistance are determined by the shape of the ship below the waterline.
Air resistance is determined by the shape of a ship above the waterline, and many proposals regarding the shape of the hull have been made to reduce this resistance.

On the other hand, frictional resistance is determined based on the submerged area of the ship using the so-called Schoenherr's formula, regardless of the shape of the ship under water. This flooded area is automatically determined when a ship shape that minimizes wave-forming resistance and vortex-forming resistance is determined based on the ship's length and width determined from the ship's stutter and volume, and frictional resistance is also determined based on this. It is determined by

Conventionally, methods for reducing this frictional resistance have been to apply paint with low frictional resistance to the submerged parts of the hull, or to move the hull away from the water surface, as in the case of hovercraft and hydrofoil boats.

Hovercraft have the advantage of being amphibious, but they also have the disadvantage of being less economical due to the large amount of air that leaks during rough seas, as well as the fact that the air leaking from all four sides generates a large amount of spray, which obstructs visibility and wets the cargo. Hydrofoils have the disadvantage of being subject to continuous strong impacts when waves are high and at high speeds.

However, the biggest drawbacks that both of these have in common are that they cannot be applied to large ships due to limitations on the size of the ship, and there are also restrictions on the wave height that can be navigated.

〔the purpose〕

The purpose of the present invention is to solve the problems of the prior art,
To provide a structure for a ship capable of reducing frictional resistance without being restricted by the size of the ship and almost unaffected by the height of waves.

〔composition〕

The frictional resistance of a ship can be expressed by the general formula v=1c・ρ・s, v2. Here, C is a coefficient determined by the shape and surface condition of the flooded part of the ship, ρ is the density of the fluid, S is the flooded area, and V is the speed of the ship.

The present invention aims to reduce ρ in the above equation and reduce the frictional resistance force F by blowing air out from the bottom of the ship and covering the bottom of the ship with air or a mixed layer of air and water. be.

That is, according to the present invention, air having a pressure higher than the water pressure at the bottom of the ship is ejected from a plurality of air outlets provided at the bottom of the ship, thereby creating a layer of air or a mixed layer of air and water between the bottom of the ship and the water. A ship is provided that is characterized in that it forms a.

In this case, depending on the shape of the bottom of the ship or the position of the air outlet, if necessary, weirs extending approximately in the longitudinal direction may be provided on both sides of the bottom of the ship to prevent the ejected air from flowing out to the sides of the ship. It is preferable.

Further, according to the second aspect of the present invention, air having a pressure higher than the water pressure at the bottom of the ship is ejected from a plurality of air jet ports provided at the bottom of the ship to create a layer of air between the bottom of the ship and the water, or between air and water. Provided is a ship characterized in that a mixed layer is formed in the bottom of the ship, and a rectifying protrusion is provided near the rear end of the bottom of the ship that substantially coincides with the axis of the propeller to reduce the amount of air drawn into the propeller.

〔Example〕

The present invention will be described in detail below with reference to FIGS. 1 to 8.

1 and 2 are diagrams showing a first embodiment of the present invention.

In FIGS. 1 and 2, a bottom flat part 2 is formed on the underside of a hull 1, and a plurality of air jet ports 3 are provided in the flat part 2. As shown in FIGS. Air having a pressure higher than the water pressure (sum of static pressure and dynamic pressure) at that depth, that is, the water pressure at the bottom of the ship, is ejected from each jet port 3 by a compressor or the like installed inside the ship. Note that line W in FIG. 1 indicates the water surface.

In FIG. 2, reference numeral 4 indicates a dead flat that indicates the outer edge of the planar portion of the bottom 2, and reference numeral 5 indicates a line on the deck.

The air jet ports 3 include two rows of jet ports parallel to each other in the longitudinal direction sandwiching the hull centerline A, and jet ports arranged in a curved line along both sides of the flat part 20 of the bottom of the ship, that is, along the inside of a dead flat line 4. A propeller 6 for propulsion is provided below the water surface W in the stern section.

In Figs. 1 and 2, when the ship moves in the direction of arrow V, air with a pressure higher than the water pressure at the bottom of the ship is continuously ejected from each air outlet 3, and this air forms an air layer or It forms a mixed layer with water and flows rearward while contacting most of the flat part 2 of the ship's bottom.

3 and 4 show a second embodiment of the present invention, and in addition to the structure of the first embodiment, this embodiment has a position near the rear end of the bottom 2 that substantially coincides with the axis of the propeller 6. A rectifying protrusion 7 is provided on the bottom 20, and weirs 8.8 are provided on the dead flat line 4 on both sides of the bottom 20 and extending substantially in the fore-and-aft direction.

Depending on the position of the propeller 6 provided at the stern, the air flowing backward may be drawn into the propeller 6, causing cavity damage and reducing propulsion efficiency.In this embodiment, a rectifying protrusion 7 is provided. Therefore, the air flowing from the air outlet 3 toward the stern can be prevented from being drawn into the propeller 6, and a decrease in propulsion efficiency can be prevented.In addition, the air blown from the air outlet 3 can be prevented from being drawn into the propeller 6. Depending on the shape of the bottom of the ship and the position of the spout, the amount that flows out to the sides of the ship and rises along the side of the ship increases. By providing a groove I8.8 that extends in the direction, air is prevented from flowing out to the sides of the hull, regardless of the shape of the bottom or the location of the air outlet.
An even surface air layer or a mixed layer with water can be maintained in most areas of the bottom of the ship.

According to the embodiments shown in FIGS. 1 to 4 above, when the ship moves in the direction of arrow V, air at a pressure higher than the water pressure at the bottom of the ship is continuously jetted from each air outlet 3. The air flows rearward while contacting the flat part 2 of the bottom of the ship, forming a poor air layer or a mixed layer with water.

The thickness of the air layer or water/air mixed layer formed on the bottom 2 of the ship varies depending on the amount of air ejected per hour and the speed of the ship, but the specific gravity (ρ in the above formula) is smaller than that of water alone. This makes it possible to greatly reduce the frictional resistance of the ship. As a result, it is possible to achieve high economic efficiency, with a lower overall resistance of the ship, a lower required engine power and lower fuel consumption.

In other words, if the bottom 2 of the submerged parts of the hull is covered with a layer of air or a mixed layer of air and water, the density ρ1 of the fluid on the surface of the bottom 2 will be smaller than the specific gravity ρ of water alone, and the frictional resistance will be reduced. decreases.

If the total flooded area is S, the area of the part of the bottom 2 in contact with the air layer or air/water mixed layer is 81, and the coefficient of frictional resistance in each part is C, then the frictional resistance force F in this example is , can be expressed by the following formula.

1] F1=-C・ρ・(S-81)v2+iC1・ρl-8
Iv2 Here, if C and C1 are almost the same, then
If both are represented by C, %F1 can be expressed by the following equation (2).

1C S・S・Ma2 in the formula (2) represents the conventional frictional resistance force in which only water contacts without an air layer or a mixed metal layer with water, and the values in parentheses in the formula (2) correspond to this. Indicates the ratio of frictional resistance.

ρ1 By the way, ρ is smaller than ρ, and 1- is smaller than l, so the value in parentheses above is smaller than l, and a part of the flooded part of the ship is divided into an air layer or air/water. By covering with a mixed layer, the frictional resistance of the ship can be reduced, and the larger the area, the higher the rate of reduction of the frictional resistance. When the ship moves from side to side, the inclination of the bottom 2 Depending on the direction, the air flows higher, and some of it floats up along the ship's side, reducing the area of the air/water mixed layer that covers the flat part of the ship's bottom.
The degree of reduction in frictional resistance may be reduced. In order to reduce this attenuation rate, it is effective to provide a plurality of rows of air jet nozzle groups arranged in the front-rear direction as shown in the figure. Furthermore, according to the inclination of the ship, the flow rate is controlled to reduce the amount of ejection from the ejection ports on the side where the bottom leaks and increase the amount of ejection on the side where the bottom is deeper, thereby maintaining the frictional resistance reduction effect. At the same time, waste of air supply power can be eliminated.

FIG. 5 shows a third embodiment in which the present invention is applied to a two-shaft wide ship.

In FIG. 5, the air outlet 3 is located at the center 11i1 of the bottom 2 of the ship.
It consists of a group of jet ports arranged parallel to each other in the front-rear direction across the bottom, and a group of jet ports arranged in two stages on a line having a predetermined spread of 9 angles from the front end and middle part of the bottom to the left and right. Depending on the size of the ship and the shape of the ship's bottom, the number of stages of Ruriko's jet ports can be arranged in three or more stages.

If the length of the hull 1 is long, depending on the shape of the dead flat line 4, the amount of air that flows out to the sides of the hull and floats up along the gunwale may increase, but as in this example, the amount of air that spreads to the left and right may increase. By providing a group of air outlets arranged in two stages at multiple angles, air can be supplied from the middle of the bottom of the ship.
Even without 8, it is possible to reduce the amount of air flowing out to the side and form a uniform air layer or air/water mixed layer over the entire bottom of the ship.

The air jet nozzle groups arranged in a line extending left and right and having multiple angles are not limited to the two-stage arrangement as shown in the figure, but can be arranged in three or more stages as necessary. Furthermore, appropriate angles and lines can be selected in consideration of the shape of the bottom of the ship, the number of stages, etc., as well as the spread angle with respect to the center line of the bottom of the ship.

The axis of each propeller 6 near the rear end of the bottom 2 and t9:
IY, a rectifying protrusion 7.7 is provided at the corresponding position to reduce the amount of air drawn in by each propeller and prevent problems such as Φ Yabitasin.
Weirs 8.8 extending substantially in the longitudinal direction along the line 4K of both side edges or dead flats are provided to prevent air from flowing out to the sides of the hull.

Note that these rectifying protrusions 7, 7 and weirs 8, 8 may be omitted depending on the case.

The structure of other parts of this embodiment is substantially the same as that of the first and second embodiments, and corresponding parts are designated by the same reference numerals (and reference numerals), and a description thereof will be omitted.

The third embodiment shown in FIG. 5 also provides the same functions and effects as the second embodiment.

FIGS. 6 and 7 are diagrams showing a fourth embodiment of the present invention applied to a fully personal watercraft.

In Fig. 6, when the watercraft is in a planing state, when the hull l is planing in the direction ■ with an angle of attack α with respect to the water surface W, the energy given to the water lO returned forward from the turning point P at the bottom 2 and the turning point. It corresponds to the sum of three energies: the horizontal component of energy due to the frictional resistance R received from the water flowing backwards from P, and the horizontal component of the pressure (lift force) L due to the water not reaching the bottom 2 at right angles. Propulsion energy (propulsion horsepower) is required to do so.

As is clear from FIG. 6, the frictional resistance force R acts on the bottom of the rear half of the hull 1, that is, the water-contacted portion 11 of the hull 1 when the boat is planing at an angle of attack α. Further, since the required lift of the ship is constant, the position of the turning point P gradually moves backward as the speed of the ship increases, the required water contact area decreases.

As shown in FIG. 7, the bottom 2 of the ship is provided with a plurality of rows (three stages in the illustrated example) of air jet ports 3 arranged in the direction across the ship in the longitudinal direction. As in the case of Embodiment 91 described above, air is ejected from these air outlets 3 at a pressure higher than the water pressure at the bottom of the ship, creating an air layer or a mixed layer of air and water between the bottom water contact area 11 and the water. form to reduce frictional resistance. Furthermore, weirs 8.8 are provided on both sides of the bottom 20 to prevent the ejected air from flowing out to the sides of the hull.

Therefore, when the jetting point P moves backward and the jetting port 3 is exposed, the air jetting from the air jetting port 3 closes this exposed jetting port, and the air jetting out from the jetting port 3 is blocked. It is controlled so that air is blown out only from the outlet 3.

Further, when the bottom 2 is not flat and has a deadrise shape such as a V-shaped cross section, it is preferable to arrange the air jet ports 3 in the longitudinal direction near the center line of the bottom. The reason is,
When there is a deadrise, the air ejected from the bottom of the ship flows to the left or right in a direction forming an angle γ as shown by vector 12 in Fig. 8, so it is necessary to sufficiently replenish the ejected air near the hull center ah. This is to facilitate the formation of an air layer or an air/water mixed layer over the entire bottom of the ship.

〔effect〕

As is clear from the above description, according to the present invention, the frictional resistance of the ship can be reduced by forming an air layer or an air/water mixed layer between the bottom of the ship and the water. A ship that can reduce frictional resistance without being restricted by size or wave height can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view showing a first embodiment of a ship having an air outlet according to the present invention, FIG. 2 is a bottom view taken from line ■-■ in FIG. 1, and FIG. 4 is a bottom view taken from line IV-IV in FIG. 3, FIG. 5 is a bottom view of the third embodiment of the present invention, and FIG. 6 is a bottom view of the fourth embodiment of the present invention. FIG. 7 is a longitudinal sectional view of the embodiment, FIG. 7 is a bottom view of FIG. 6, and FIG. 8 is an explanatory bottom view illustrating the flow direction of jet air at the bottom of a ship having a deadrise. 1... Hull, 2... Bottom, 3... Air outlet, 6
... Propeller, 7 ... Rectifier projection, 8 ... Weir, 1
1... Bottom water contact area, A... Bottom (hull) center line, ■
...Direction of the ship, W...Water surface, α...Angle of elevation,
P... Turning point, R2... Frictional resistance of the water contact area.

Claims (5)

[Claims] (1) Air is ejected at a pressure higher than the water pressure at the bottom of the ship from multiple air outlets provided on the bottom of the ship, creating a layer of air between the bottom of the ship and the water, forming a mixed layer of air and water. A ship. (2) The ship according to claim 1, wherein at least a portion of the air jet ports are arranged along a straight line or a curved line having a predetermined angle with respect to the center line in the longitudinal direction. (3) Air jet amount adjustment means that operates in response to the ship's fore-aft, side-to-side motion, or changes in attitude due to changes in ship speed, and that self-manufactured to reduce the amount of air jetted out from the jet ports located on the higher side. A ship according to claim 1 or 2, characterized in that the ship is provided with: (4) Any one of claims 1 to 3, characterized in that weirs extending substantially in the longitudinal direction are provided on both sides of the bottom of the ship to prevent the ejected air from flowing out to the sides of the ship. Ships listed in. (5) Air with a pressure higher than the water pressure at the bottom of the ship is ejected from multiple air outlets provided on the bottom of the ship to form a layer of air or a mixed layer of air and water between the bottom of the ship and the water. A ship characterized by reducing the amount of air drawn into the propeller by providing a rectifying protrusion near the rear end that substantially coincides with the axis of the propeller.