JPS6152038B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a boat piece for a ship that is capable of equalizing the flow flowing into a screw propeller at the stern of a boat.

When the screw propeller rotates and the ship is sailing, the flow around the hull at the stern becomes extremely complex, and this complicated and turbulent flow flows into the screw propeller.

In particular, the flow at the bottom of the ship near the screw propeller flows diagonally upward from the bottom of the ship, and when the flow hits the shoe piece, the flow is disturbed and the flow speed is significantly slowed down.

When a propeller rotates in such a flow field, the thrust and moment generated from the propeller blades fluctuate violently, causing hull vibration and cavitation.

Figure 1 is a side view of the stern section, in which 01 is the screw propeller, 02 is the stern frame, 03 is the rudder installed behind the screw propeller 01, and 0
Reference numeral 4 denotes a shoe piece that is provided at the lower end of the stern frame 02 and supports the rudder 03 from below.

FIG. 2 is a detailed view of the vicinity of the shew piece 04, and the arrow indicates the direction of the flow around the shew piece 04 when the ship is sailing.

Figure 3 shows the flow velocity distribution at an arbitrary radius within the propeller rotation circle in a cross section at the screw propeller 01 position of a ship equipped with a conventional shoe piece. It hits right above the showpiece 04.

In this case, when the screw propeller 01 rotates and the ship sails, the water near the ship piece 04 flows diagonally upward from the bottom of the ship. The flow in this part is quite fast, so the flow is
4, the flow rate becomes very turbulent and very slow. Then, the extremely slow and turbulent flow flows into the screw propeller 01, and the flow velocity distribution near the screw propeller 01 fluctuates significantly and becomes very complicated.

As a result, propeller catation is more likely to occur, and the thrust and moment of the propeller do not fluctuate significantly, resulting in increased hull vibration.

The present invention was proposed in order to eliminate such drawbacks, and the present invention is provided below the propeller, with one end disposed at the lower end of the stern frame of the ship and the other end disposed at the rudder support member that supports the rudder. The ship's shoe piece is characterized in that a plurality of through holes are arranged from the lower end of the ship's upper end to the upper end thereof and are inclined backwardly upwardly and in front of the propeller.

When the shew piece of the present invention is provided, the flow flowing upward from the bottom of the ship near the shew piece while the ship is sailing flows into the vicinity of the propeller through the through hole provided in the shew piece, so that the flow velocity distribution at the propeller position is is equalized.

As a result, the occurrence of propeller cavitation is reduced, and the fluctuations in propeller thrust and moment are reduced, and hull vibration is also reduced.

Next, one embodiment of the device of the present invention will be described based on the drawings.

4 and 5 are a partially cutaway side view and a longitudinal sectional plan view of the showpiece according to this embodiment. In the figure, 2 is the stern frame, 3 is the rudder installed behind the screw propeller (not shown), 4 is the shoe piece attached to the lower end of the stern frame 2, and the rudder receiver 5
to support the rudder 3 from below. 6 is show peace 4
With multiple through holes drilled at an upward slope,
The flow that flows diagonally upward from below the screw piece 4 is guided to the vicinity directly below the screw propeller.

In a ship equipped with a shew piece having such a structure, when the screw propeller (not shown) rotates and the ship sails, the water near the shew piece 4 flows diagonally upward from the bottom of the ship, but part of the flow is , the flow is blocked and turbulent by the shoe piece 4, causing the flow to slow down, but some of the flow passes through the through hole 6, so the flow does not slow down and flows into the vicinity directly below the screw propeller.

Therefore, the flow velocity distribution at the propeller position becomes nearly uniform.

Figure 6 is a diagram showing the results of measuring the flow velocity distribution at an arbitrary radius within the propeller rotation circle in a cross section of the screw propeller position of a ship equipped with this show piece. is directly above the show piece 4.

Comparing FIG. 6 with FIG. 3, which shows the flow velocity distribution when a conventional show piece is installed, it can be seen that the flow velocity directly below the propeller in FIG. 6 has been increased, and the flow velocity has been made uniform as a whole.

In this way, with this device, the flow flowing into the propeller is made more uniform than when using a conventional showpiece, which reduces the occurrence of propeller cavitation and also reduces fluctuations in propeller thrust and moment. It has the advantage of being smaller and reducing hull vibration.

[Brief explanation of the drawing]

Figure 1 is a side view showing the stern of the ship, Figure 2 is an enlarged view of the vicinity of the shew piece in Figure 1, and Figure 3 is a side view showing the stern of the ship.
The figure is a diagram showing the flow velocity distribution within the rotation circle of the screw propeller when a conventional showpiece is provided, and FIGS. 4 and 5 show an embodiment of the device of the present invention,
Of these, Figure 4 is a partially cutaway enlarged side view showing the vicinity of the shippiece, Figure 5 is a longitudinal sectional plan view taken along line V-V in Figure 4, and Figure 6 is a screen shot of a ship equipped with the above-mentioned equipment. FIG. 3 is a diagram showing the flow velocity distribution within the rotation circle of the U-propeller. 01...Screw propeller, 02,2...Stern frame, 03,3...Rudder, 04,4...Sew piece, 5
...Rudder support material, 6...Through hole.

Claims (1)

[Claims] 1. In a ship's shew piece, which is located below the propeller, one end is placed on the lower end of the ship's stern frame and the other end is placed on the rudder support that supports the rudder. A ship piece, characterized in that a plurality of through holes are arranged in a row below and in front of the propeller.