JP2000118495A - Suction device for jet water in water jet propulsion ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To jet a water jet efficiently by improving a suction port of jet water. SOLUTION: In a water jet propulsion ship, two suction ports 5 of jet water are arranged in juxtaposition, and the suction ducts 6 thereof are confluent at the inlet part of a pump 3. The suction port 5 is set to a large size and a velocity of flow of suction is reduced and formed in an oblong shape formed along a water flow. Further, the suction duct 6 is elongated and a suction dynamic pressure is injected as a water jet without incurring of a loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a jet water suction device for a water jet propulsion ship.

[0002]

2. Description of the Related Art Conventionally, in a water jet propulsion ship, it is well known that jet water is sucked from one suction port and jetted from one nozzle, and the jet water sucked from one suction port is known. Injection from a plurality of nozzles is also known.

[0003]

In the conventional water jet propulsion ship, when the suction flow rate of the jet water in the suction port and the suction duct is high, the velocity head loss (Hl = fV)
^2/2 g) is large, which reduces the efficiency of the water jet. For this reason, the frictional resistance is reduced by slowing down the water flow in the suction duct or polishing the inside so that the water flow smoothly flows in the suction duct.

[0004]

SUMMARY OF THE INVENTION The present invention has solved the above-mentioned problems in a water jet propulsion ship by greatly changing the structure of a jet water suction portion. In other words, changing the number of jet water suction ports from the conventional one to two, lowering the flow velocity in the suction duct to greatly reduce the velocity head loss, and changing the structure of the suction part to reduce the jet water The resistance loss is reduced by flowing smoothly in the suction duct.

[0005] That is, the gist of the present invention is that in a water jet propulsion boat, two jet water suction ports provided at the bottom of the ship are provided in parallel, and an intake duct connected to the suction ports is provided at a position in front of the pump. It has been merged. It is desirable that the two suction ports have an opening area as large as possible with respect to the pump, and a guide plate is provided at a junction of the two intake ducts so that the water flow is smoothly sucked into the pump. It is effective to provide.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is constructed as described above, and two jet water suction ports are provided to increase the opening area of the suction ports, so that the speed of the water flow in the intake duct is reduced. Thus, the water jet loss can be efficiently generated by lowering the velocity head loss (Hl = f · V ² / 2g), which has conventionally been the largest loss. In addition, by providing two suction ports in parallel, it is possible to form an oval-shaped suction port along the water flow, to smoothly suck the water flow, and furthermore, to a junction portion of the two suction ducts. The provided guide plate can efficiently generate a water jet without generating turbulent flow at the suction port of the pump. Hereinafter, the present invention will be specifically described with reference to the drawings.

[0007]

FIG. 1 is a schematic side view of a water jet propulsion ship according to the present invention, in which a water jet propulsion section is cut away. In the drawing, reference numeral 1 denotes a hull, 2 denotes a nozzle for jetting water jets, 3 denotes a pump for generating water jets, 4 denotes a driving engine of the pump 3 and 5
Is a jet water suction port, and 6 is a jet water suction duct.

As shown in FIGS. 2 to 4, two jet water inlets 5 are provided at the bottom of the ship, and their respective suction ducts 6 are joined together before the pump 3 as shown in FIG. And one. A guide plate 7 is provided at the joint of the suction duct 6 so as to protrude forward in a semicircular shape as shown in FIG.

In other words, the jet water suction device according to the present invention has two suction ports 5 for one injection nozzle 2.
And the suction duct 6 is attached to the front side of the pump 3. The area of the suction port 5 is the same as the area of one suction port provided for the pump 3. The flow rate in the suction duct 6 can be made lower than the flow rate in the suction duct of one suction port as half or more. The flow is rectified by a guide plate 7 in front of the pump 3 so as to be similar to the water flow in one suction duct.

The jet water suction device according to the present invention comprises:
As described above, the two suction ports 5 for one injection nozzle 2 suck the jet water and reduce the flow velocity in the suction duct 6. Speed head loss (Hl = fV ² / 2g, where f is a coefficient), which has the greatest effect on the efficiency of the water jet in running, can be reduced, enabling efficient sailing It is.

Further, since the two suction ports 5 are provided in a pair on the left and right avoiding the keel of the hull, they can be opened in an oval shape along the traveling direction of the hull, and the suction water can be smoothly sucked into the duct. 6, the water jet can be efficiently generated with low resistance. Furthermore, the suction port 5
Is divided into two, so that each suction port 5 is smaller than the conventional one, and it is easy to attach a screen or the like. Then, if one of them is blocked by dust or the like, it is possible to sail without stopping.

The advantages of the present invention as described above are shown in FIGS.
This will be further described based on FIG. 6 and FIG. 7 schematically show the flow of the suction water flow when the ship is sailed using the apparatus according to the present invention. FIG. 8 and FIG. 9 schematically show the flow of the suction water flow when the ship sails with one suction port corresponding to the two suction ports 5 described above. As is apparent from a comparison between FIG. 7 and FIG. 9, the water flow is smoothly decelerated in the long suction duct 6 along the hull 1 at the two suction ports 5 according to the present invention, and then the water is pressurized by the pump 3. It is injected. On the other hand, in the conventional single suction port, the pressure is reduced by a short distance from the large suction port, and then the pressure is increased by the pump as a constant speed flow. In other words, this indicates that the velocity head loss is large because the water flow changes greatly in the short suction duct.

[0013]

As described above, according to the present invention, the water jet propulsion ship is provided with two jet water suction ports, and the jet water flow rate in the suction duct is reduced.
The water head loss can be reduced and the water jet can be jetted efficiently, and the suction water can be smoothly introduced into the pump to reduce the frictional resistance in the suction duct. It is easy to set along the direction, and it is also easy to manufacture accessories such as a screen.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a water jet propulsion ship according to the present invention.

FIG. 2 is also a schematic rear view of the same.

FIG. 3 is also a schematic plan view of the jet water suction device.

FIG. 4 is a bottom view of a jet water suction port portion.

FIG. 5 is a vertical sectional side view of a joint portion of the suction duct.

FIG. 6 is a plan view of a jet suction device according to the present invention.

FIG. 7 is coordinates showing a flow state of a water flow in the suction device of FIG. 6;

FIG. 8 is a side view of a suction device having one suction port.

FIG. 9 is coordinates showing a flow state of a water flow in the suction device of FIG. 8;

[Explanation of symbols]

 3 pump 5 suction port 6 suction duct 7 guide plate

Claims (3)

[Claims] In a water jet propulsion ship, two jet water suction ports 5 provided on the bottom of a ship are provided in parallel, and a suction duct 6 connected to the suction port 5 is joined at a portion in front of the pump 3. A feature of the jet water suction device in a water jet propulsion ship. 2. The opening area of one virtual intake duct corresponding to the two suction ducts 6 that merge before the pump 3 so that one opening area of the two suction ports 5 provided in parallel with each other is provided. 2. The jet water suction device for a water jet propulsion ship according to claim 1, wherein the opening area is at least half the opening area as compared with the area. 3. A semi-circular guide that bulges forward as viewed from the side at a joint portion of the suction duct 6 joined before the pump 3 in a vertical plane including a center line thereof. 2. The water jet water suction device for a water jet propulsion ship according to claim 1, further comprising a plate.