JPH0637196B2 - Soundproof type propeller - Google Patents

Description

The present invention is applied to a fixed-pitch propeller or a variable-pitch propeller for ship propulsion, or a fixed-pitch propeller or a variable-pitch propeller in a side thruster for turning a ship. Soundproof propeller.

[Conventional technology]

Propeller sound is a resonance between the natural frequency of the propeller blade and the Karman vortex from the trailing edge of the propeller blade generated by the rotation of the propeller blade. Changing the natural frequency of a propeller blade is subject to many restrictions in terms of strength and vibration, and its implementation is almost impossible.

Therefore, in order to change the Karman vortex generation frequency, conventionally, a thin wall method in which the trailing edge of the propeller blade has a sharp edge (see FIG. 9) and a thick wall method in which the trailing edge of the propeller blade is thick (10th (See the figure), or a combination of these two methods is adopted, and a method that makes it difficult to generate Karman vortices due to turbulence, that is, a method in which part of the trailing edge contour of the propeller blade is serrated ( See FIGS. 11 and 12 and Japanese Patent Publication No. 55-275).

[Problems to be solved by the invention]

By the way, the propeller blades have a large number of natural frequencies because the cross-sectional shape is not uniform in terms of performance. Therefore, there is a limit in controlling the generation frequency of the Karman vortex generated from the trailing edge of the propeller blade by the thin-walled method, the thick-walled method, or a combination thereof, and it is not possible to completely avoid resonance with the natural frequency of the propeller blade. However, it is very difficult for a special ship, and the actual ship is forced to make a modification by a few trial runs.

Further, a blade whose trailing edge has a saw-toothed contour so as to prevent the Karman vortex from being generated is vulnerable to foreign matter contact at the time of reversal and deteriorates the product image.

The present invention is intended to solve the above-mentioned problems, and it is possible to prevent the generation of Karman vortices by generating turbulence at the trailing edge of the propeller blades without impairing the propeller efficiency. The purpose is to provide a type propeller.

[Means for solving problems]

In order to achieve the above-mentioned object, the noise suppression type propeller of the present invention is a turbulent flow disposed on the back trailing edge of a propeller blade in the vicinity of the trailing edge of the trailing edge and along the trailing edge. It is characterized in that it has a forming groove portion, and that a water flow hole penetrating from the pressure surface to the back surface of the propeller blade is provided in the groove portion.

In such an embodiment of the present invention, a large number of groove portions having, for example, an angle of about 45 ° with respect to the flowing water direction are formed in the trailing edge portion on the back surface side of the propeller blade in a dispersed manner along the blade trailing edge. Is provided with a water flow hole penetrating from the back surface of the propeller blade to the pressure surface.

[Action]

In the above-described noise suppression type propeller of the present invention, turbulent flow occurs due to the groove portion along the blade trailing edge, and the pressure flowing water is blown from the pressure surface of the propeller blade to the back side through the flowing water hole in the groove portion, Turbulence is increased and Karman vortices are prevented from occurring.

The turbulent flow is generated only in the groove portion, and the turbulent flow can be generated only by the pressure flowing water blown out from the flowing water hole penetrating the back surface of the propeller blade and the pressure surface.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 4 show a noise-prevention type propeller as a first embodiment of the present invention. FIG. 1 is a front view of a propeller blade viewed from the back side thereof, and FIG. 2 is a II part of FIG. Enlarged view of the third
The figure is a sectional view taken along the line III-III in FIG. 2, and FIG. 4 is the IV in FIG.
FIG. 5 is a cross-sectional view taken along the line IV, and FIGS. 5 to 7 show a main part of a noise-prevention type propeller as a second embodiment of the present invention, and FIG. 5 shows a trailing edge portion of the propeller blade. Partial view, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is VII-VII in FIG.
FIG.

In the first embodiment of the present invention shown in FIGS. 1 to 4, a large number of groove portions 2 are formed in the rear edge portion of the rear surface 1a of the propeller blade 1 in the vicinity of the rear edge of the rear edge portion along the rear edge. Are distributed.

Then, every other one of these groove portions 2 is provided with a water flow hole 3 penetrating from the back surface 1a of the propeller blade 1 to the pressure surface 1b.

When the propeller radius is R, the range of the propeller noise prevention processing for forming the groove portion 2 and the water flow hole 3 is, as shown in FIG. 1, a propeller blade back surface between 0.4R and 0.95R in the radial direction. It is the trailing edge portion, and in the spanwise direction, it is within a range not exceeding about 50 mm from the trailing end portion of the propeller blade. As shown in FIG. 2, the groove portion 2 is composed of a pair of long and short grooves, and the long groove 2a
Is provided at a position at an angle of 45 ° with respect to the flowing direction A, and the short groove 2b is provided at a position perpendicular to the long groove 2a. And the water flow hole 3 which penetrates from the back surface 1a of the propeller blade 1 to the pressure surface 1b is provided in the long groove 2a.

The dimensional ratio of each part at the trailing edge of the propeller blade is set as shown in FIGS.
The dimension of is set in millimeters as shown in FIG. In addition, the code | symbol C in a figure shows chamfering.

In the second embodiment of the present invention shown in FIGS. 5 to 7, a plurality of groove portions 2 are formed in parallel with the trailing edge 1c of the propeller blade 1, and in the center of each groove portion 2 from the back surface 1a of the propeller blade 1 to the pressure surface. There is a water flow hole 3 penetrating to 1b.

The cross-sectional shape of the trailing edge portion of the propeller blade 1 is as shown in FIG. 6 in correspondence with FIG. 3 described above.

Further, the depth of the groove portion 2 is set as shown in FIG. 7 in units of millimeter, and has an arc-shaped groove bottom having an appropriate radius R ′.

FIG. 8 shows a general shape of a marine propeller, and a blade section B in the figure shows a section on a radius R ₁ . Such a propeller blade has a large number of natural frequencies, and a Karman vortex generated from the trailing edge of the propeller blade due to rotation resonates with an arbitrary natural frequency to generate a propeller ringing sound, which results in sound wave probing. It is an obstacle.

Various methods as shown in FIGS. 9 to 12 have been implemented as means for avoiding such resonance. However, in order to avoid resonance reliably, 3 to 4 test runs are required. There is also a problem that the strength is weak against contact with foreign matter at the time. It should be noted that the symbol h _{0 in} FIGS. 9 and 10 indicates the planned offset, and d ₀ and d ₁ indicate the trailing edge diameter of the propeller blades.

In the noise reduction type propeller of the present invention, in the case of the first embodiment shown in FIGS. 1 to 4 and in the case of the second embodiment shown in FIGS. Since the groove 2 that does not hinder the turbulence and generates turbulence is provided, the Karman vortex is prevented from being generated.

Furthermore, the back surface of the propeller blade 1 caused by the rotation of the propeller
Utilizing the pressure difference between 1a and pressure surface 1b,
Since the water flow hole 3 for causing the pressure water to flow in 1a is provided in the groove portion 2, the turbulent flow can be further increased, thereby more reliably preventing the generation of Karman vortices.

The groove 2 and the water flow hole 3 have the effect of preventing the generation of Karman vortices even individually.

By thus preventing the generation of Karman vortices in the propeller blade 1, the generation of propeller noise is sufficiently suppressed.

FIG. 13 compares a graph P showing a frequency analysis result when the groove 2 and the water flow hole 3 are provided with the present invention and a graph Q showing a frequency analysis result when the groove 2 and the water flow hole 3 are not provided. In the case of the present invention, the generation of ringing noise is sufficiently prevented.

[Effects of the Invention] As described in detail above, according to the noise suppression propeller of the present invention, the following effects and advantages are obtained.

(1) Near the trailing edge of the trailing edge of the back surface of the propeller blade, a turbulent flow occurs due to the provision of a groove along the trailing edge, and this turbulent flow prevents the generation of Karman vortices, and Occurrence can be avoided.

(2) In the groove portion, by providing a water flow hole penetrating from the pressure surface of the propeller blade to the back surface, the pressure water flow generated along with the rotation of the propeller can be caused to flow to the back surface, and the turbulent flow can be increased. In this way, the generation of Karman vortices is sufficiently suppressed.

(3) The turbulent flow generation function of each of the groove portion and the water flow hole 3 can maintain the function even when viewed individually, but in the present invention, due to their cooperation, the propeller noise is generated. It will be fully prevented.

[Brief description of drawings]

1 to 4 show a noise-prevention type propeller as a first embodiment of the present invention. FIG. 1 is a front view of a propeller blade viewed from the back side thereof, and FIG. 2 is a II part of FIG. Enlarged view of the third
The figure is a sectional view taken along the line III-III in FIG. 2, and FIG. 4 is the IV in FIG.
FIG. 5 is a cross-sectional view taken along the line IV-IV, and FIGS.
FIG. 5 is a partial view showing the trailing edge portion of the propeller blade, FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5, and FIG. 7 is VII-V in FIG.
FIG. 8 is a sectional view taken along the arrow II, FIG. 8 is an explanatory view showing a general shape of a ship propeller, and FIGS. 9 to 12 are all explanatory views showing a ship propeller equipped with a conventional propeller noise suppression means. FIG. 13 is a graph showing a comparison of the ringing characteristics between the case of the anti-noise propeller of the present invention and the case of the conventional propeller. 1 ... propeller blade, 1a ... propeller blade back surface, 1b ... propeller blade pressure surface, 1c ... propeller blade trailing edge, 2 ... groove
Part , 2a ... long groove, 2b ... short groove, 3 ... running water hole.

Claims (1)

[Claims] 1. A turbulent flow forming groove portion is provided at a rear trailing edge portion of a propeller blade in the vicinity of the trailing edge portion of the trailing edge portion and along the trailing edge portion, and the groove portion of the propeller blade is provided in the groove portion. A noise reduction propeller, which is provided with a water flow hole penetrating from the pressure side to the back side.