JPH05286488A - Water jet protrulsion vessel - Google Patents

Abstract

PURPOSE:To improve the suction performance for a water jet pump. CONSTITUTION:A water taking-in port 12 for a water jet pump 11 is formed on a stern edge 13 as the part where the water stream static pressure on the periphery of a hull 1 becomes max. Accordingly, the suction performance of the water jet pump 11 can be increased by utilizing the high static pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a water jet propulsion ship used as a high speed boat, and is intended to improve the suction performance of a water jet pump.

[0002]

2. Description of the Related Art Recently, the demand for high-speed boats has been increasing, and when the boat speed becomes higher than about 40 knots, the adoption of a propeller used as a propulsion device for ordinary boats lowers the propulsion efficiency. , It is extremely difficult due to the occurrence of severe cavitation on the propeller blade surface.

For this reason, a water jet propulsion system using a water jet pump has been adopted as a propulsion device for high-speed boats.

In a conventional water jet propulsion device, for example, as shown in FIG. 4, a water jet pump 3 and an engine 4 are installed in an engine room 2 of a hull 1, and suction is made from a water intake 5 formed at the bottom of the hull 1. Water is sucked through the pipe 6, pressurized water is jetted from the stern jet port 8 through the discharge pipe 7, and a propulsive force is obtained by its reaction force.

In the conventional water jet propulsion ship, in order to improve the propulsion performance, the length of the suction pipe 6 to the water jet pump 3 is shortened so that the frictional resistance in the pipeline is minimized. The water intake 5 is arranged at the bottom of the engine room 2 near the water jet pump 3.

[0006]

However, the water jet pump 3 in such a water jet propulsion ship is used.
As for the suction performance of, when the water intake 5 is formed at the bottom of the engine room 2 of the hull 1, the water intake 5 is almost in the center of the hull 1, and it depends on the flow of water around the hull 1. Since water is taken from a place with low static pressure, the suction performance is poor.

For example, looking at the distribution of the flow velocity v and the distribution of the static pressure p around the high speed boat traveling at the boat speed V ₀ , FIG.
As shown in, the case of ignoring the viscosity of water, the following equation is established by Bernoulli's theorem.

P + 1 / 2ρv ² = p ₀ + 1 / 2ρV ₀ ² where p ₀ is the static pressure corresponding to the uniform flow V ₀ .

This tendency is maintained even when the viscosity of water is taken into consideration, and the static pressure is low in the center of the hull where the flow velocity v is high.

Therefore, the suction from the water intake 5 formed at the bottom of the engine room 2 in the center of the hull 1 having a low static pressure has a problem that the suction performance of the water jet pump 3 deteriorates.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a water jet propulsion ship capable of improving the suction performance to the water jet pump.

[0012]

In order to solve the problems of the above-mentioned prior art, the water jet propulsion ship of the present invention is a water jet propulsion ship in which water is jetted and propelled by a water jet pump. It is characterized in that the intake port is formed at a place where static pressure is higher than the dynamic pressure of water around the hull.

[0013]

According to this water jet propulsion ship, the water jet pump has a water intake port at a portion where the static pressure is higher than the dynamic pressure of the water flow around the hull, such as the stern end and the bow end.
Alternatively, they are formed in the vicinity of these, and the static pressure higher than the dynamic pressure is utilized to improve the suction performance.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 3 are vertical sectional views of an embodiment of the water jet propulsion ship according to the present invention. In this water jet propulsion ship 10, the water intake port 12 to the water jet pump 11 is formed at a place where the static pressure is higher than the dynamic pressure of the water around the hull to improve the suction efficiency.

As is clear from the distribution of the flow velocity v of water and the static pressure p shown in FIG. 5, the static pressure at which the intake 12 is to be formed is high in the center of the hull where the flow velocity v is high. Considering the fact that the static pressure p is high near the bow and stern where the flow velocity v is low and conversely the flow velocity v is slow,
At the bow end and the stern end, which are the points), the flow velocity v becomes 0 and the static pressure p becomes the maximum.

Therefore, for example, in the water jet propulsion ship 10 shown in FIG. 1, the water intake 12 to the water jet pump 11 is formed at the stern end 13 where the static pressure becomes maximum, and the water jet from the water jet 12 is formed. The pump 11 is connected to the suction pipe 14 of a straight pipe, and the water jet pump 11 and the injection port 15 of the stern end 13 are communicated with each other by a discharge pipe 16 including a 90-degree curved pipe.

In the water jet propulsion ship 20 shown in FIG. 2, the water jet pump 21 has a water intake port 22.
Is formed at the stern end 23 where the static pressure is maximum, and the intake port 22 to the water jet pump 21 are connected by a suction pipe 24 including a 90-degree curved pipe, and the water jet pump 21 and the stern end are connected. A straight discharge pipe 26 communicates up to the injection port 25 of 23.

Such a water jet propulsion ship 10,
In 20, the intakes 12 and 22 to the water jet pumps 11 and 21 are formed at the stern ends 13 and 23 where the static pressure becomes high. Therefore, the static pressure p is utilized to make the water jet pumps 11 and 21. The suction efficiency can be improved.

The suction pipes 14, 24 and the discharge pipe 16,
Whether the shape of 26 is a straight pipe or a pipe including a curved pipe may be selected according to the friction loss in the pipe obtained according to the length of the pipe. However, depending on the arrangement of the equipment and the like, the curved pipe may be provided in both of them without intervening in one of them.

Further, in the water jet propulsion ship 30 shown in FIG. 3, the water intake 32 to the water jet pump 31 is provided.
Is formed at the bow end 37 where the static pressure becomes maximum, and the intake pipe 32 to the water jet pump 31 are connected by a suction pipe 34 including a 90-degree curved pipe, and the water jet pump 31 and the stern end are connected. A straight pipe discharge pipe 36 communicates with the injection port 35 of 33.

Even when the intake port 32 to the water jet pump 31 is formed at the bow end 37 where the static pressure becomes maximum like the water jet propulsion ship 30, the static pressure should be utilized to improve the suction efficiency. You can Also in this case, the arrangement of the straight pipe and the curved pipe may be changed.

In each of the above embodiments, the water intakes 12, 22, 32 to the water jet pumps 11, 21, 31 are used.
The stern end 13, 23 or the bow end 37 where the static pressure is maximum
However, there are cases where it is difficult to dispose this way due to constraints such as the hull structure. In this case, in the vicinity of the stern ends 13 and 23 and near the bow end 37, the intake 12, 22 and 32 may be formed, and even in these cases, since the static pressure is still high, the suction efficiency can be improved.

The present invention is not limited to the above embodiment, and various changes may be made to the constituent elements without departing from the gist of the present invention.

[0024]

As described above in detail with reference to the embodiments, according to the water jet propulsion ship of the present invention, the intake port to the water jet pump has a static pressure compared to the dynamic pressure of the water flow around the hull. Since it is designed to be formed at a high part, such as the stern end or the bow end, or in the vicinity of these,
The suction performance of the water jet pump can be improved by using a static pressure higher than the dynamic pressure.

As a result, further energy saving and speeding up of the water jet propulsion ship can be achieved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a water jet propulsion ship of the present invention.

FIG. 2 is a longitudinal sectional view of another embodiment of the water jet propulsion ship of the present invention.

FIG. 3 is a vertical sectional view of still another embodiment of the water jet propulsion ship of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional water jet propulsion ship.

FIG. 5 is an explanatory diagram of flow velocity and static pressure distribution around the hull.

[Explanation of symbols]

 1 Hull 2 Engine Room 4 Engine 10, 20, 30 Water Jet Propulsion Vessel 11, 21, 31 Water Jet Pump 12, 22, 32 Water Intake 13, 23, 33 Stern End 14, 24, 34 Suction Pipe 15, 25, 35 Spout 16,26,36 Discharge pipe 37 Bow end

Claims (1)

[Claims] 1. A water jet propulsion ship in which water is jetted and propelled by a water jet pump, wherein an intake port to the water jet pump is formed at a place where static pressure is higher than dynamic pressure of water around the hull. A characteristic water jet propulsion ship.