JP6944095B2 - Propulsion resistance reduction device for ships - Google Patents

Description

The present invention relates to a propulsion resistance reducing device for a ship, and in particular, the pressure wave generated at the stern is converted into a propulsive force, and as a result, the resistance associated with the traveling of the ship is reduced and the fuel consumption is reduced, which is economical. It relates to a propulsion resistance reducing device for ships for the purpose of increasing the fuel consumption.

A commonly used method for reducing stern resistance is to attach a guide plate along the gentle slope of the bottom of the ship to regulate the water flow to the propulsion device. Further, as for the one that tries to change the twisted wake of the propeller into a propulsive force, there is a one in which a fin for rectification is provided between two propellers.

Regarding the former propulsion device, it seems that a certain effect has been obtained for a ship with a special shape called a paddock hull, but it is not widely applicable, and in many general hulls, the entire hull is generated at the stern. The gathering wave once pushes up the water surface at the stern and then remains as a large V-shaped wave, and energy is lost. The latter, which attempts to rectify the wake of the propeller, has the effect of directing the upward flow due to the swirling flow in the horizontal direction, but does not have the effect of converting the V-shaped wave generated at the stern into propulsive force.

JP-A-2004-136781 JP 2011098704

As a technical background, it is said that fossil fuels are almost depleted, and the practical application of technology that has the effect of reducing the fuel used for operation is an urgent issue. There are many known techniques for improving propulsion devices, but there is no method that can be widely applied to yachts and can substantially reduce propulsion resistance due to stern waves.
There is a demand for a method that can be easily applied to existing ships, is inexpensive, and has a wide range of uses that can reduce propulsion resistance.

The problem to be solved by the present invention is that the energy of the V-shaped wave generated at the stern is effectively recovered, and the size, speed, propulsion method, and steering function of the ship are not affected, and the general purpose is as a propulsion resistance reducing device. It provides a propulsion resistance reduction device for ships, which is characterized and has a significant improvement effect at a low implementation cost.

The means for solving the above-mentioned problems of the present invention is a first fin formed by inclining the front edge laterally protruding from the hull below the waterline at the stern to the rear and close to the front of the first fin. The present invention provides a propulsion resistance reducing device for a ship, characterized in that a second fin protruding laterally from the hull is fixedly provided.

During navigation, the water pushed to the side of the hull at the bow becomes an upward flow from the bottom of the stern, a flow toward the center from both sides, gathers behind the stern, and the speed component is deprived by the generation of vortices. After pushing up the water surface due to the rise in static pressure, it becomes a V-shaped wave and loses its energy. As the speed of the ship increases, the wave-making resistance due to this V-shaped wave becomes much larger than the frictional resistance between water and the side of the ship, and occupies a large part of the propulsion resistance. A force in the propulsion direction can be generated by suppressing the bulge of the water surface generated behind the hull due to the upward flow from the bottom of the ship and the diagonal flow gathering from the side to the center with flat fins. As a result, the propulsion resistance can be significantly reduced. The state will be described with reference to the figure.

FIG. 1 is a side view showing one embodiment of the present invention. FIG. 2 is a plan view showing one embodiment of the present invention. FIG. 1 is a partial side view showing one embodiment of the present invention. FIG. 2 is a partial plan view showing one embodiment of the present invention. FIG. 3 is a partial plan view showing another embodiment of the present invention.

An embodiment for simplifying and realizing the function of the propulsion resistance reducing device for ships of the present invention without impairing the function is shown.

FIG. 1 is a side view showing one embodiment of the marine propulsion resistance reducing device of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 shows one embodiment of the marine propulsion resistance reducing device of the present invention. It is a partial side view, and FIG. 4 is a partial plan view thereof. In FIGS. 1, 2, 3, and 4, a first flat fin 3 is fixed to the stern portion 2 of the hull 1 of the ship by a stay 4. A flat second fin 5 is provided in the vicinity of the front of the first fin 3. The trailing edge of the second fin 5 is formed so that both ends are slightly rearward, and is configured so as to maintain a certain distance from the leading edge of the first fin 3. It is desirable that the second fin 5 is installed slightly above the first fin 3.
In FIG. 2, the chain line 6 shows the waterline of the ship, the solid lines 7, 8 and 9 show the water flow flowing near the stern of the hull, and the broken lines 10, 11 and 12 show the water flow when there is no fin. The cross section of the first fin 3 is formed in a shape such that the front edge portion is slightly thick and the trailing edge side is thin and faces the horizontal direction, and the cross section of the second fin 5 is the leading edge portion like the tail of an aircraft. It is a little thick and the trailing edge is thin. The leading edge of the first fin 3 is formed so that both ends face backward. The reason is that floating matter on the water surface is not caught during navigation, and the reason why both ends of the trailing edge of the second fin 5 are configured to face backward is constant with the leading edge of the first fin. This is because the interval between the two is maintained and the rectifying effect of both is effectively exhibited. FIG. 5 is a plan view showing another embodiment of the present invention. In FIG. 5, a corrugated portion 13 is formed at the trailing edge of the second fin 5.
[motion]

The operation of the marine propulsion resistance reducing device of the present invention shown in the above embodiment will be described.
As described in the section on the effects of the invention mentioned above, the water pushed to the side of the hull at the bow during navigation becomes an upward flow from the bottom of the hull at the stern, and flows toward the center from both sides, and becomes a flow toward the center at the stern. They gather in the rear and try to push up the water surface, but the generation of vortices is restricted by the rectifying effect of the second fin 5, and the stern heads toward the first fin 3 from diagonally below while containing a large amount of velocity components. The first fin 3 bends the direction of this flow horizontally and guides it backward. As a result, the rise of the water surface at the rear part of the hull is limited, the generation of V-shaped waves is suppressed, and the propulsion resistance is reduced.
When navigating at high speed in ordinary ships that are not equipped with this device, especially small ones, a force such as sinking the stern is generated by the reaction of the upward flow from the bottom of the stern. As a result, the waterline 6 changes as shown by the broken line 14, and the bow is raised, so that it can be clearly confirmed that the above action is occurring. On the other hand, when the first fin 3 and the second fin 5 are attached, the stern does not sink and the hull can navigate horizontally, so that the effects of the first fin 3 and the second fin 5 are obtained. Can be clearly confirmed visually. In the experiment, a device for visually measuring the ship speed was towed behind the hull to clearly confirm its practical effect.
In the embodiment shown in FIG. 5, when actually navigating on the natural water surface, the optimum value of the distance between the trailing edge of the second fin 5 and the leading edge of the first fin 3 is determined by the magnitude of the wave, the speed fluctuation, and the like. Not the same. At that time, due to the effect of the corrugated portion 13, the water flow itself selects and passes through the portion where the distance from the leading edge of the first fin 3 is optimum, so that unnecessary direction change and velocity change in the flow path in this portion. This is to reduce the flow path resistance.
The above structure is a device fixed to the hull, has nothing to do with the propulsion device and the steering operation, and can be easily mounted on the hull in a practical state and the effect can be easily confirmed. In general, improving the shape of the hull requires extremely large costs, including manufacturing and experiments, and it is often hesitant to decide whether or not to implement it in consideration of the contrast with this effect. In this proposal, the effect can be theoretically confirmed by CFD without making an actual ship and experimenting, so it is easy to suppress the counterargument from the cost aspect, and the hurdle to implement it is low.

As is clear from the above description, the propulsion resistance reduction device for ships of the present invention applies energy generated by V-shaped waves generated at the stern by a simple means of fixing the first and second fins near the stern of the hull. It can be effectively recovered and the propulsion resistance can be significantly reduced. It is possible that the second fin 5 can be omitted for a motor boat or the like whose stern shape is cut into a plane perpendicular to the traveling direction. In addition, in the type of ship where the engine unit is installed outside the ship, even if the fins are attached to the engine unit instead of directly to the hull, the fixing method is devised, and the resulting configuration is the same as the above explanation. If there is, it does not impair the gist of the present invention. By providing a second fin 5 on a general ship type ship, it can be widely applied to the hull for many purposes such as yachts and large tankers, and because the structure is simple and inexpensive, it is extremely easy to implement. Yes, the effect of reducing fuel costs in the water transportation industry is extremely remarkable.

1 Hull 2 Stern 3 1st fin 5 2nd fin 13 Corrugated part

Claims (2)

A fin-shaped member in a substantially horizontal direction overhanging rearward is fixedly provided to the stern portion of the hull, and the planar shape of the fin-shaped member is formed so that the tip of the leading edge faces slightly rearward, and the cross section is the leading edge portion. It is characterized by being slightly thick and facing downward, and the trailing edge is thinly formed in a shape that faces horizontally. The leading edge of the second fin is oriented slightly downward, and the trailing edge of the second fin is provided so as to be close to the leading edge of the first fin. Device. A fin-shaped member in a substantially horizontal direction overhanging rearward is fixedly provided to the stern portion of the hull, and the planar shape of the fin-shaped member is formed so that the tip of the leading edge faces slightly rearward, and the cross section is the leading edge portion. It is characterized by being slightly thick and facing downward, and the trailing edge is thinly formed in a shape that faces horizontally. The feature is that the leading edge of the second fin is in a slightly downward state, the horizontal shape of the trailing edge of the second fin is corrugated, and the leading edge of the second fin is provided so as to be close to the leading edge of the first fin. Navigation resistance reduction device for ships.

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