JP2000247295A - Water jet ship - Google Patents

Abstract

(57) [Object] To provide a water jet ship capable of eliminating uneven pressure distribution generated at an inlet portion of a water intake for sucking water. A roller member (12) rotated by a rotation drive device (11) is attached to a downstream lip (3) of a water inlet (2) for taking in water for water jet formed at the bottom of the ship. It is arranged so that it is exposed in the water intake 2,
A first pressure sensor 14 is disposed at a position downstream of the roll member 12 in the intake port 3 of the lip 3, and a second pressure sensor is disposed at a position downstream of the roll member 12 at the bottom of the lip 3 at the ship bottom. 15 is arranged, and the roll member 12 is rotated so that water flows more in a direction where the pressure detected by the pressure sensors 14 and 15 is smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water jet ship.

[0002]

2. Description of the Related Art Some high-speed boats use water jets. As shown in FIG. 3, a water intake 52 for taking in water for water jets is provided at the bottom 51 of such a high-speed boat. Is provided. By the way, the shape of the water intake 52 is determined by the IVR calculated from the ship speed and the suction speed at which the water jet pump operates most frequently.
(Expressed as pump suction speed / ship speed, also referred to as ship speed / velocity ratio) and the pressure distribution and cavitation generated at the lip, which is the inlet of the water intake, determined to maximize propulsion efficiency It had been.

[0003]

As described above, the intake 52
Is calculated in consideration of the IVR, pressure distribution, and cavitation. However, in actual operation, many transient states of acceleration and deceleration occur, and the design is affected by disturbances such as wind and waves. There is a problem that matching is difficult.

[0004] For example, when the shape of the intake port and the design IVR match, as shown in FIG.
In the vicinity of 3, a uniform positive pressure distribution is formed in the vertical direction, so that the water suction efficiency is improved and the occurrence of cavitation is prevented. However, as shown in FIG.
When the IVR during navigation becomes smaller, the stagnation point S becomes
It moves (occurs) to the upper surface side of the lip portion 53, and thus the lower surface side of the lip portion 53 becomes negative pressure, and the pressure distribution becomes uneven and cavitation occurs. FIG.
As shown in the figure, when the IVR during navigation becomes larger than the design IVR, the stagnation point S moves (occurs) to the lower surface side of the lip portion 53, and again the upper surface side of the lip portion 53 becomes negative pressure, and the pressure distribution Becomes non-uniform.

As described above, when the stagnation point generated at the lip portion of the water intake, that is, at the inlet portion, is shifted to the upper surface side or the lower surface side, the pressure distribution at the inlet portion becomes uneven, the water suction efficiency is deteriorated, and the cavitation is reduced. Occurs,
Accordingly, there is a problem that the propulsion performance is reduced and the fatigue of the hull structure is adversely affected. Therefore,
SUMMARY OF THE INVENTION It is an object of the present invention to provide a water jet ship that can eliminate uneven pressure distribution generated at an inlet of a water intake port.

[0006]

In order to solve the above-mentioned problems, a water jet type marine vessel according to the present invention is provided with a water jet water intake port formed at the bottom of a boat, which has a downstream lip portion. The roller member rotated by the rotation drive device is disposed so that a part of the outer peripheral surface thereof is exposed in the water intake, and the first pressure sensor is disposed at a position downstream of the roll member in the water intake of the lip portion. In addition, a second pressure sensor is disposed at a position downstream of the roll member at the bottom of the lip portion, and the rotation driving device of the roll member is controlled based on the detected pressures from both pressure sensors. It is.

In the above configuration, when the detected pressure of the first pressure sensor is larger than that of the second pressure sensor, the roller member is rotated in a direction in which the amount of water taken into the water inlet decreases, and the first pressure sensor is rotated. When the pressure detected by the sensor is smaller than that of the second pressure sensor, the roller member is rotated in a direction in which the amount of water taken into the water intake increases.

In the above configuration, by rotating the roller member from the larger pressure to the smaller pressure, the pressure distribution inside and outside the lip can be made uniform, and therefore, the efficiency of suction into the water intake can be reduced. Deterioration and cavitation are prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A water jet ship according to an embodiment of the present invention will be described below with reference to FIGS. As shown in FIGS. 1 and 2, a water intake 2 for taking in water jet water is formed in a bottom 1 of a high-speed boat (an example of a ship).
At the distal end of the downstream lip portion 3 which is the entrance portion, a cylindrical roller member 12 rotated by a rotary drive device (a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor) 11 is used. The portion is exposed to the inside of the water intake 2 so as to be rotatable around an axis along the width direction (the hull width direction) of the water intake 2 via, for example, a bearing member 13. Although not shown, the mounting portion of the roller member 12 to the lip portion 3 has a water-tight structure, and is provided with a packing material, a partition wall, and the like.

[0010] Further, at a position on the back side (downstream position) of the lip portion 3 in the water intake port 2 with respect to the roller member 12,
A first pressure sensor 14 for detecting seawater pressure in the intake port 2 is provided, and seawater is provided at a position (downstream position) on the outer surface of the hull (outer surface of the bottom of the ship) of the lip portion 3 and behind the roller member 12. A second pressure sensor 15 for detecting pressure is provided.

Further, both pressure sensors 14,
A control device 16 for inputting the detection pressure signal from the pressure sensor 15 and controlling the driving of the rotary drive device 11 is provided. Accordingly, the roller member 12
The rotation direction and the rotation speed of are controlled. That is, in the control device 16, the ratio of the detected pressure from the second pressure sensor 15 to the detected pressure of the first pressure sensor 14 (the detected pressure of the first pressure sensor / the detected pressure of the second pressure sensor) is obtained. The detected pressure ratio is converted to IVR.

When the converted IVR is larger than the design IVR, the roller member 12 is rotated in a direction in which the amount of water taken into the water inlet 2 decreases, and conversely,
When the converted IVR is larger than the design IVR, the roller member 12 is rotated in a direction in which the amount of water taken into the water inlet 2 increases. In other words, when the IVR during navigation is smaller than the design IVR, the stagnation point moves to the upper surface side of the lip portion 3 (back side of the water intake), and the lower surface side of the lip portion 3 (outside surface of the water intake). Then it becomes negative pressure.

Therefore, the pressure inside and outside the lip portion 3 is detected by the control device 16 based on the detected pressure signals from the two pressure sensors 14 and 15, and according to the pressure ratio (when the pressure ratio is appropriate). The rotation direction and the rotation speed of the roller member 12 are controlled by the rotation driving device 11. In this case, the roller member 12 corresponds to FIG.
Is rotated in the direction of arrow a, and the flow of seawater near the water intake 2 is guided to the outer surface side of the lip 3, and the pressure at the deep position of the water intake 2 is reduced. pressure at the outer surface side is increased, thus also called pressure distribution [C _P distribution in the upper and lower surfaces of the lip portion ^{3, P / (ρU 2/} 2)
(Returned to a proper position of the stagnation point), thereby preventing a reduction in the suction efficiency into the water intake port 2 and the occurrence of cavitation.

Contrary to the above, the IV during navigation is
When R (converted IVR) is larger than the design IVR, the stagnation point moves to the lower surface side of the lip portion 3 and becomes negative pressure on the upper surface side of the lip portion 3.
The roller member 12 is rotated in the direction of arrow b in FIG. That is, since the flow of seawater near the intake port 2 is guided to the upper surface side of the lip portion 3, the pressure on the outer surface side of the ship bottom decreases, and the pressure increases on the upper surface side of the lip portion 3,
Therefore, the pressure distribution on the upper and lower surfaces of the lip portion 3 is made uniform, and a reduction in the suction efficiency into the water intake port 2 and the occurrence of cavitation are prevented.

As described above, since the roller member 12 is rotated from the larger pressure to the smaller pressure, the pressure distribution on the upper and lower surfaces of the lip portion 3 is made uniform, and the efficiency of suction into the water intake 2 is reduced. Deterioration and cavitation are prevented. That is, the flow generated by the rotation of the roller member 12 plays a role of circulation, and moves the stagnation point in an ideal direction. Therefore, even if the pressure distribution at the tip of the lip portion 3 changes, the IVR changes. , Kept in an ideal shape.

[0016]

As described above, according to the structure of the water jet type ship of the present invention, the roller member and the pressure sensor for detecting the pressure inside and outside the water intake port are provided at the tip of the lip portion of the water intake port. At the same time, since the rotation of the roller member is controlled in accordance with the difference between the two pressures, for example, by rotating the roller member from a larger pressure to a smaller pressure, the pressure distribution inside and outside the lip portion is made uniform. Therefore, a reduction in the suction efficiency into the water intake and the occurrence of cavitation can be prevented. That is, it is possible to prevent a decrease in propulsion performance and to prevent a bad influence on fatigue of the hull structure.

[Brief description of the drawings]

FIG. 1 is a sectional view of the vicinity of an intake port of a ship according to an embodiment of the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a sectional view of a hull bottom showing a water intake port of a ship in a conventional example.

FIG. 4 is a cross-sectional view of a main part showing an operation of a water intake in a conventional example.

FIG. 5 is a cross-sectional view of a main part showing an operation of a water intake in a conventional example.

FIG. 6 is a cross-sectional view of a main part showing an operation of a water intake in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 hull bottom 2 water intake 3 lip 11 rotation drive device 12 roller member 14 first pressure sensor 15 second pressure sensor 16 control device

Claims (2)

[Claims] 1. A watercraft propelled by a water jet pump, wherein a roller member rotated by a rotary drive device is provided on a downstream lip portion of a water intake port formed at a bottom portion of the watercraft for taking in water for water jet. Is disposed such that a part of the outer peripheral surface thereof is exposed in the water intake, and the first portion of the lip is located downstream of the roll member in the water intake.
A pressure sensor is disposed, and a second pressure sensor is disposed at a position downstream of the roll member at the bottom of the lip portion, and a rotation driving device for the roll member is controlled based on pressures detected from both pressure sensors. A water jet ship characterized by having a configuration as described above. 2. When the pressure detected by the first pressure sensor is higher than that detected by the second pressure sensor, the roller member is rotated in a direction in which water taken into the water intake decreases, and the pressure detected by the first pressure sensor is reduced. 2. The water jet ship according to claim 1, wherein when the pressure is smaller than that of the second pressure sensor, the roller member is rotated in a direction in which the amount of water taken into the water intake increases.