JPS60139586A - Frictional resistance reducer for shipping - Google Patents

Abstract

PURPOSE:To aim at reduction in frictional resistance to the hull, by interconnecting a bubble generator to a chest installed in a hull front bottom plate part, while making bubbles so as to be spouted to the bottom plate after leading them into a partition formed by a projection installed in a ship's longitudinal direction. CONSTITUTION:Seawater sucked up from a sea chest 11 is led into a bubble generator consisting of an ejector 8 and a stirring pump 7 and then interconnected to a chest 4 installed in a ship's front bottom plate part. A projection 6 is installed in a bottom plate extending over a hull longitudinal direction, forming a partition which spouts air bubbles. These bubbles spouted out of the chest 4 are led astern along the partition formed by the projection 6 without being spread. With this constitution, frictional resistance to the hull is efficiently reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for reducing the frictional resistance between water and a ship's hull during navigation of a ship.

Conventionally, ships generally have the following basic problems. During navigation, the ship's speed is forced to decrease due to the frictional resistance of the water against the ship's hull, and in order to overcome this, the propulsion horsepower must be increased, which increases fuel costs and worsens economic efficiency.

This invention was made to solve these problems, and its purpose is to reduce the IlK frictional resistance of water against the hull during navigation of a ship, thereby reducing the propulsion horsepower. The object of the present invention is to obtain a frictional resistance reducing device for ships, which can increase ship speed and reduce fuel costs.

To describe this invention with reference to the drawings, in FIGS. 1 to 5, a bubble water generating device 2 provided on a hull 1 is communicated with a chest 4 formed at the bottom 3 of the front part of the hull 1. This is a frictional resistance reducing device for a ship, characterized in that a protrusion 6 is provided on the bottom shell plate 5 of the boat in the longitudinal direction thereof.

To explain this in detail, the bubble water generator 2 includes, for example, a stirring pump 7, an ejector 8. Seawater is formed from piping 9°, atmospheric suction pipe 10, etc., and is suctioned through 7-chest 11. Seawater is pressurized by stirring pump 7, and a part of the pressure water on the discharge side is supplied as driving water to ejector 8. 8
The air sucked from the atmospheric suction pipe 10 is forced into the suction side of the stirring pump 7.

Next, the air and seawater pushed into the stirring pump 7 are stirred by the impeller of the stirring pump 7, and the air becomes a fine air layer, which is discharged into the chest 4 as bubble water and released from the opening 12 to the outside. (See Figure 1).

The bubbles of the bubble water discharged from the opening 12 rise as shown in FIG. 6 due to the difference in specific gravity with the seawater, and are guided toward the stern by the water current that accompanies the ship's speed. In the figure, the direction to the arrow indicates the bow, and the direction 4B indicates the stern direction. In this case, the bottom shell plate 5 has protrusions 6 in its length direction.
The protrusions 6 effectively guide the released bubbles in the water toward the stern and prevent them from flowing out toward the side shell 13. and protrusion 7
The bubble layers that try to float between each other are guided toward the stern, aggregate, and become coarse particles, growing from a bubble layer with a high air mixing ratio to an air layer (Figure 7). (See arrow C).

When we look at the air layer that has grown beyond the size of the protrusion 6, it climbs over the protrusion 6, moves toward the side, climbs over the protrusion 6a at the end, and floats along the side skin 13 (
(See arrow C in Figure 7).

In this case, preferably, as shown in FIG.
It is formed with an inclination angle θ such that it spreads outward toward the top. The reason for this formation is that the air layer and bubble layer that are about to float tend to separate from the side shell 13 due to the water flow caused by the ship's speed, but consideration has been given to keeping them floating close to the side shell 13. It is something.

Next, at the stern, if the air layer is caught in the propulsion propeller 14, the propulsion efficiency will decrease due to the occurrence of cavitation, so the shape of the stern is set to /EV shape as shown in Fig. 4, and the air layer is Layers and bubbles play on this slope and are made to float quickly.

By increasing the inclination angle αb1, as shown by αα, the flying speed will be increased. The reason why the propulsion resistance is reduced by enclosing an air layer between the bottom shell plate 5, etc. and the water is that the viscosity of air is approximately 1/1000 of that of water.
This is because the viscous frictional resistance, which accounts for most of the propulsion resistance, decreases as the ratio of the contact area with the air beneath the water increases. Also, in the case of contact in the state of bubble water, the viscous frictional resistance decreases according to the mutual contact ratio, similar to the above.

Next, in the case shown in FIGS. 8 and 9, the bilge keel 15 is provided close to the flat surface of the bottom shell 5, and a sufficient depth of the air layer can be secured. In addition, the height of the bilge keel 15 should be made sufficiently high so that the bottom skin 5 is constantly surrounded by an air layer against rolling, as shown in Fig. 10. It is also conceivable that by forming a minute diameter hole in the bilge keel 15, some of the air can flow out to the side skin 13, thereby reducing the viscous frictional resistance.

Next, if the length of the hull is very long and significant rolling occurs, the air layer and bubble layer may not be sufficiently guided to the stern and may float up from the middle. In such a case, as shown in Figure 11, play chess along the length of the ship.
This could be dealt with by providing multiple stages.

Next, Figure 12 shows the previous dC bubble generator 2 and another same device 2 (l), a driving water pump 16 for the ejector 8 is provided, suction air is sucked by the ejector 8, and the driving water is Bubble water is obtained by mixing with water and raising the pressure, which has the advantage of less wear on the pump impeller due to cavitation.

By having the present invention configured as described above, the viscous frictional resistance between the hull and the water can be significantly reduced, and the propulsion efficiency can be improved. Therefore, ship speed can be increased. On the other hand, the propulsion horsepower can be reduced by that amount, and fuel costs can be saved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a front view schematically showing a frictional resistance reducing device for a ship, FIG. 2 is a plan view of the same, FIG. 3 is a sectional view of a part of the front surface, and FIG. The figure is a rear view of the same device, FIG. 5 is a cross-sectional view of a part of the front side of the same device, FIG. 6 is a schematic partial view showing a part of the same device, FIG. 7 is a diagram explaining the operation of the same device, and FIG. 9 is a front view of the device shown in FIG. 8, FIG. 10 is a view showing another state of the device shown in FIG. 9, and FIG. 11 is a front view of the device showing another embodiment of the invention. FIG. 12 is a schematic front view of the same device showing still another embodiment of the invention, and FIG. 12 is a circuit diagram of a part of the same device showing another embodiment of the invention. 1...Hull 2...Bubble water generator 3...Bottom 4...Chest 5...Bottom outer plate 6...Protrusion Agent Patent attorney Yugai Saito 2 names 91 No. 8 Yuga 1] Figure 11

Claims (1)

[Claims] A bubbly water generating device provided on the hull is communicated with a chest provided at the bottom of the front part of the hull, and a projection is provided on the bottom outer plate of the hull in the longitudinal direction thereof. Frictional resistance reduction device.