JPS61193990A - Marine screw propeller - Google Patents

Abstract

PURPOSE:To prevent the occurrence of excessive suction pressure caused by separation of a flow at a tip end of a propeller blade, by installing a water injection nozzle in the propeller blade tip end and, when this tip end comes nearer to a stern bottom surface, spouting water from this injection nozzle. CONSTITUTION:A water injection nozzle 7 is formed in the back of a tip end of a propeller blade 1, and this injection nozzle 7 is connected to a water feed passage 3 being formed inside the propeller 1. A water intake 8 of this water feed passage is designed so as to be matched with the water feed port formed in a rear end of a propeller bossing B in order. When the propeller blade 1 comes nearer to a stern bottom part 2, the water intake 8 of the water feed passage 3 becomes matched with the water feed port 6, thus water is spouted out of the water injection nozzle 7 of the propeller blade 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a screw propeller provided below the bottom surface of a stern ship.

[Prior Art 1 Conventionally, there has been a marine screw propeller as shown in Fig. 7.
It has a plurality of propeller blades 1 protruding from a propeller boss 4 and is provided below the stern bottom surface 2 of the stern.

[Problem to be Solved by the Invention 1] However, one of the major problems caused by such conventional marine screw propellers is pressure fluctuation at the stern. One of the major causes of pressure fluctuations is unsteady cavitation that occurs in propellers. This is caused by excessive negative pressure on the propeller blade due to uneven flow at the stern when the propeller blade 1 rotates in the vicinity of the stern bottom surface 2, as shown by arrow a, as shown in Figure 7. This occurs on the rear surface (see the portion indicated by the reference numeral in FIG. 8). The occurrence and disappearance of such cavitation may be caused by vibration problems or propeller blades depending on various conditions.
causes erosion (erosion: hereinafter referred to as "cavitation erosion").

In addition, the ship speed is V. , if a part of the propeller rotating part at a certain rotation angle is taken out and the average flow velocity of that part is V, then the average wake W according to the rotation angle is expressed as w=1-(ν/V0). The relationship between θ and the wake rate is shown in FIG. 9 based on the rotation angle θ of the propeller. Here, as shown in FIG. 7, it is assumed that θ=O when the propeller blade is upward.

The present invention aims to solve the above-mentioned problems by significantly alleviating the phenomenon of excessive negative pressure on the blade surface of the propeller blade tip when the propeller blade tip approaches the bottom surface of the stern. It is an object of the present invention to provide a marine screw propeller that can prevent separation of the flow along the blade surface of the tip of the propeller blade, thereby preventing vibration and cavitation erosion from occurring.

[Means for Solving the Problems 1] Therefore, in the marine screw propeller of the present invention, in the screw propeller provided below the bottom surface of the stern,
In order to prevent the separation of the flow along the blade surface of the propeller blade tip when the propeller blade tip approaches the bottom surface of the ship, a water spout is formed at the propeller blade tip, and a water spout is formed inside the propeller blade. A water supply path communicating with the water spout is formed in the water supply path, and the path from the water supply source through the water supply path to the water spout opens only when the tip of the propeller blade approaches the bottom surface of the ship. The provision of a valve mechanism is considered a vP sign.

[Operation 1] In the above-described marine screw propeller of the present invention, water is jetted out from the water spout of the propeller blade tip when the propeller blade tip approaches the bottom surface of the stern. This prevents excessive negative pressure from occurring on the propeller blades.

[Example 1] Hereinafter, a marine screw propeller as an embodiment of the present invention will be shown with reference to the drawings. Fig. 1 is a partial view schematically showing its schematic structure, and Fig. 2 is a partial view showing the schematic structure of the propeller, and Fig. A sectional view of the propeller blade along the arrow line, Figures 3 and 4 are both schematic diagrams for explaining the action, Figure 5 is a partial side view thereof, Figure 6
The figure is a perspective view schematically showing the vicinity of the propeller blade root.

The present marine screw propeller also has a plurality of propeller blades 1 which are provided below the stern bottom surface 2 and protrude from a propeller boss 4, as shown in FIG.

However, the following points differ from the conventional one. That is, as shown in FIG. 1, a lower water jet is formed on the rear surface of the tip of each propeller blade 1.

Further, inside each propeller blade 1, as shown in FIGS. 1 and 2, a water supply passage 3 is formed which communicates with the water jet lower.

This water supply passage 3 further extends from the blade root of the propeller blade 1 into the propeller boss 4 as shown in Figs. It opens at a portion facing the rear end surface of the singe B (which is fixedly provided on the hull side).

By the way, a water supply port 6 that can be sequentially aligned with the water intake port 8 of each water supply path 3 is opened at the upper end of the rear end surface of the propeller bossing B. It is connected to a water intake port 5 connected to a water supply source (such as a pump or an accumulator) (not shown).

As a result, when the propeller blade 1 approaches the stern bottom part 2,
That is, when the propeller blade 1 faces upward, the water intake port 8 of the water supply channel 3 formed in the propeller blade 1 is aligned with the water supply port 6, and the propeller blade 1 is closest to the stern bottom part 2.
Water is spouted from the water spout lower.

That is, the propeller boss 4 and the water intake port 8 or water supply port 6 of the water supply channel 3 constitute a valve mechanism VL that opens only when the tip of the propeller blade 1 approaches the stern bottom 2. The valve mechanism VL is provided in a path from the water supply source to the water spout lower via the water supply path 3.

With the above configuration, the propellers rotate and each propeller H
1 approaches the part of the stern bottom where the floating current is large (when each propeller blade 1 approaches the stern bottom 2), the third to
As shown in Fig. 6, the water intake port 8 of the water supply path 3 formed in the propeller blade 4 and the water supply port 6 formed in the propeller bossing B are aligned, so that the propeller! ! The centrifugal force generated by one revolution and the negative pressure at the blade tip generate water flows as shown by the arrows in Figures 5 and 6. This water stream is ejected from the water jet lower at the propeller blade tip to prevent excessive negative pressure near the blade tip.

This action is performed for each propeller blade 1 because the water intake port 8 and water supply port 6 of each propeller blade 1 are sequentially aligned as the propeller rotates.

Since the lower water jets at each blade tip are located at appropriate locations that are most effective in preventing the generation of cavity silane, it is possible to effectively prevent the generation of cavity silane.

In this way, the present marine screw propeller can prevent an excessive negative pressure state that causes cavitation when the propeller blade 1 approaches the stern bottom 2.

This prevents cavitation from occurring, and the vibrations and cavitation erosion caused by this can be sufficiently prevented.

Note that the water jet lower formed at the tip of the propeller blade 1 may have one opening, or may have multiple openings.

Further, by interposing a valve in the path leading from the water supply source to the water spout lower via the water supply path 3, the approach of the propeller blades to the stern ship bottom 2 is detected by an appropriate detection means, and this detection means The valve may be controlled to open based on the detection result from the above. Such a control system can be easily constructed using a simple position sensor, a microcomputer, and a V driver (drive circuit), but in this case, it is preferable to use a solenoid valve as the valve.

[Effects of the Invention 1] As detailed above, according to the marine screw propeller of the present invention, in the screw propeller provided below the bottom surface of the stern, a water spout is formed at the tip of the propeller blade, and the propeller A water supply path communicating with the water spout is formed inside the blade, and a path from the water supply source to the water spout through the water supply path is such that the tip of the propeller blade approaches the bottom surface of the ship. Since a valve mechanism is provided that opens only when the propeller blade tip approaches the bottom surface of the ship, it is possible to significantly alleviate the excessive negative pressure phenomenon at the propeller blade tip when the propeller blade tip approaches the bottom of the ship. This has the advantage that separation of the flow along the blade surface of the propeller can be prevented, and as a result, vibrations caused by the propeller and occurrence of cavitation erosion can be sufficiently prevented.

[Brief explanation of drawings]

Figures 1 to 6 show a marine screw propeller as an embodiment of the present invention. Figure 1 is a partial view schematically showing its schematic structure, and Figure 2 is a line taken along the arrows ■-■ in Figure 1. Figure 3.4 is a schematic diagram for explaining its function, Figure 5 is a partial side view thereof, and Figure 6 is a perspective view schematically showing the vicinity of the root of the propeller blade. and
Figures 7 to 9 show a conventional marine screw propeller. Figure 7 is a schematic diagram showing the relationship between the screw propeller and the bottom of the stern, and Figure 8 is a schematic diagram showing how cavitation occurs. , FIG. 9 is a graph showing the relationship between the rotation angle of the screw propeller and the wake rate. 1. Propeller blade, 2. Bottom of stern, 3. Water supply channel, 4. Provera boss, 5. Water intake, 6. Water supply port, 7. Water spout, 8. Water Intake port, B...blower bossing, VL...valve mechanism. Sub-Agent Patent Attorney Yoshihiko Iinuma Figure 1 Figure 2 Figure 3 Figure 4 Figure 5”3 Figure 6

Claims (1)

[Claims] In the screw propeller provided below the bottom surface of the stern, in order to prevent separation of the flow along the blade surface of the propeller blade tip when the propeller blade tip approaches the bottom surface of the ship,
A water spout is formed at the tip of the propeller blade, and
A water supply path communicating with the water spout is formed inside the propeller blade, and a path from the water supply source through the water supply path to the water spout is connected to the bottom surface of the propeller blade tip. A marine screw propeller characterized by being provided with a valve mechanism that opens only when approaching.