JPH04212695A - Screw propeller - Google Patents

Abstract

PURPOSE:To offer such a screw propeller that is made so as to improve the extent of properller efficiency by contriving in regard to the propeller screw in use on a ship, especially pertaining to a propeller hub. CONSTITUTION:In a screw propeller with plural pieces of propeller blades projected in the radial direction from a propeller hub 2, in order to keep off the occurrence of any hub vortex heading for the rear from the propeller hub 2, it is provided with plural pieces of slits on a surface part of the propeller hub 2. With these slits, the hub vortex is restrained from occurring, through which the extent of propeller efficiency is made so as to be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw propeller used in ships, aircraft, etc.

0002

2. Description of the Related Art Conventional screw propellers used in ships include those shown in FIG. 11 (side view) and FIG. 12 (perspective view), in which a plurality of propeller blades 1 extend radially from a propeller hub 2. It is set to protrude.

[0003] This screw propeller is rotationally driven by an engine to generate thrust.

0004

[Problems to be Solved by the Invention] By the way, in the conventional screw propeller as described above, during its rotation operation,
As shown in FIG. 11, a blade tip vortex 4 is generated from the blade tip 3 of each propeller blade 1, and a hub vortex 6 is generated from the rear end 5 of the propeller hub 2.

[0005] The rotational direction of the hub vortex 6 is the same as the rotational direction of this screw propeller, and the rotational direction of the blade tip vortex 4 is opposite.

As shown in FIGS. 11 and 12, the hub vortex 6 is created by bending the flow S along the propeller hub 2 between the propeller blades 1 and 1 in the rotational direction, and as it moves towards the rear end 5 of the propeller hub 2. Although it is a highly developed type of propeller and has quite strong rotational energy, this only provides a rotational flow in the same direction as the screw propeller in the wake of the propeller, and does not contribute to an increase in thrust.

[0007]Therefore, there is a problem in that the energy given by the engine to generate the hub vortex 6 is not converted into thrust, resulting in a reduction in propulsion efficiency.

[0008] The present invention aims to solve such problems, and in order to prevent the generation of hub vortices,
An object of the present invention is to provide a screw propeller in which propeller efficiency can be improved by adding innovation to the propeller hub.

[0009]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the screw propeller of the present invention is provided with a plurality of propeller blades protruding radially from a propeller hub, and a plurality of propeller blades are provided on the surface of the propeller hub. It is characterized by the formation of cut grooves.

0010

[Operation] In the screw propeller of the present invention described above, during rotation operation, the plurality of grooves formed on the surface of the propeller hub catch the flow flowing out from the trailing edge of the blade with the inner wall of the groove. , which acts to weaken the rotational force of the flow and prevent the generation of hub vortices.

[0011]

[Embodiment] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Figs. 1 to 5 show a screw propeller as a first embodiment of the present invention, and Fig. 1 is a side view thereof, and Fig. 2
3 is a side view showing the main parts thereof, FIG. 4 is a sectional view taken along the line A-A in FIG. 3, and FIG. 5 is a graph showing its characteristics.

As shown in FIGS. 1 and 2, this screw propeller, like the conventional screw propeller,
A plurality of propeller blades 1 are provided to protrude from a propeller hub 2 in the radial direction.

In the screw propeller according to the first embodiment of the present invention, in particular, on the surface of the rear end portion 2a of the propeller hub 2, a plurality of holes are formed at an angle approximately equal to the pitch angle of the blade root portion of the propeller blade 1. A cut groove 7 is formed.

As shown in FIGS. 3 and 4, this cut groove 7 has a gently inclined guide surface 8a and a guide surface 8a so as to easily introduce the flow flowing out from the trailing edge of the propeller blade.
It is formed with an end surface 8 that intersects with the guide surface 8a so as to block the flow guided along the guide surface 8a. The end surface 8 is formed such that in each cross section orthogonal to the propeller axis, the extension direction of the line segment along each of the cross sections of the end surface 8 is perpendicular to the propeller axis.

Note that a propeller cap is normally provided at the rear end portion 2a of the propeller hub 2, and herein, this portion is collectively referred to as the propeller hub.

The screw propeller of this first embodiment is as follows:
Since the screw propeller is configured as described above, when the screw propeller rotates, the flow flowing out from the trailing edge of the propeller blade 1 is guided by the guide surface 8a in the notched groove 7 and enters the notched groove 7. , comes to abut against the end face 8.

[0017] Therefore, the rotation of the flow flowing out from the trailing edge of the propeller blade is stopped, thereby preventing the generation of a hub vortex rearward from the rear end 5 of the propeller hub. In other words, the hub vortex (see reference numeral 6 in FIG. 11) that occurs in the conventional screw propeller disappears or its strength can be weakened. Note that the reference numeral 4 in FIG. 1 indicates a blade tip vortex.

In this way, in the screw propeller of this embodiment, the generation of hub vortices is suppressed, thereby reducing the swirling energy of the flow flowing out to the rear of the propeller, improving propeller efficiency. The structure is simple,
Even in existing marine propellers, there is an advantage that the propeller efficiency can be sufficiently improved simply by forming the cut grooves 7.

FIG. 5 shows the measurement results when five cut grooves 7, which are equal to the number of propeller blades 1, are provided at an angle equal to the pitch angle of the blade root according to this embodiment, and the measurement results when there are no cut grooves. As is clear from this graph, higher propeller efficiency can be obtained by providing the cut grooves 7 as in this embodiment.

Next, a description will be given of a screw propeller as a second embodiment of the present invention. FIG. 6 shows a side view of the screw propeller.
7 is a perspective view thereof, FIG. 8 is a sectional view taken along the line B--B in FIG. 6, and FIG. 9 is a graph showing its characteristics.

As shown in FIGS. 6 and 7, this screw propeller is also provided with a plurality of propeller blades 1 protruding from a propeller hub 2 in the radial direction.

In the screw propeller according to the second embodiment, a pitch angle approximately equal to the pitch angle of the blade root of the propeller blade 1 is formed on the surface of the propeller hub 2, especially between the adjacent propeller blades 1, 1. A plurality of cut grooves 7' are formed at angles. As shown in FIG. 8, this cut groove 7' has a gently inclined guide surface 8a and a flow guided along the guide surface 8a so as to easily introduce the flow flowing out from the trailing edge of the propeller blade. It is formed with an end surface 8 that intersects with the guide surface 8a so as to be able to dam the guide surface 8a. The end surface 8 is formed such that in each cross section orthogonal to the propeller axis, the extension direction of the line segment along each of the cross sections of the end surface 8 is perpendicular to the propeller axis.

Since the screw propeller of the second embodiment of the present invention is constructed as described above, when the screw propeller rotates, the flow flowing out from the trailing edge of the propeller blade 1 is directed to the notched groove 7. Guide surface 8a at '
It is guided into the cut groove 7' and comes to abut against the end surface 8.

[0024] Therefore, the rotation of the flow flowing out from the trailing edge of the propeller blade is stopped, and as a result, the hub vortex (see reference numeral 6 in Fig. 11) generated in the conventional screw propeller disappears or its You will be able to weaken the strength. Note that the reference numeral 4 in FIG. 6 indicates a blade tip vortex.

[0025] In this way, in the case of the screw propeller of this second embodiment as well, the generation of hub vortices is suppressed, so that the swirling energy of the flow flowing out to the rear of the propeller is reduced, and the propeller efficiency is improved. As a result, the structure is simple, and even in existing marine propellers, there is an advantage that the propeller efficiency can be sufficiently improved by simply forming the cut grooves 7'.

FIG. 9 shows the measurement results when five cut grooves 7', the same as the number of propeller blades 1, are provided at an angle equal to the pitch angle of the blade root according to the second embodiment, and the measurement results when there are no cut grooves. As is clear from this graph, the cut groove 7 as in this example
′ allows higher propeller efficiency to be obtained.

FIG. 10 corresponds to FIG. 2 and FIG.
It is a perspective view which shows the screw propeller as 3rd Example of this invention.

In this third embodiment, the cut groove 7 in the first embodiment and the cut groove 7 in the second embodiment are
As shown in FIG. 10, a cut groove 7'' is formed continuously on the surface of the propeller hub 2 from between adjacent propeller blades 1 to the rear end. ing.

Therefore, in the case of the screw propeller of the third embodiment, the effects obtained by integrating the respective cases of the first and second embodiments described above are obtained, and the hub vortex (Fig. 11
(see reference numeral 6) is sufficiently suppressed, resulting in high propeller efficiency.

[0030]

Effects of the Invention As detailed above, the screw propeller of the present invention provides the following effects and advantages. (1) A simple structure with multiple cut grooves formed on the surface of the propeller hub suppresses the generation of hub vortices, which had previously been considered a problem, thereby improving propeller efficiency. You will be able to do it. (2) Even in existing marine propellers, there is an advantage that the propeller efficiency can be sufficiently improved simply by forming cut grooves.

[Brief explanation of the drawing]

FIG. 1 is a side view of a screw propeller as a first embodiment of the present invention.

FIG. 2 is a perspective view of the screw propeller of FIG. 1;

FIG. 3 is a side view showing essential parts of the screw propeller shown in FIGS. 1 and 2. FIG.

FIG. 4 is a sectional view taken along the line AA in FIG. 3;

FIG. 5 is a graph showing the characteristics of the screw propeller.

FIG. 6 is a side view of a screw propeller as a second embodiment of the present invention.

FIG. 7 is a perspective view of the screw propeller of FIG. 6;

8 is a sectional view taken along the line BB in FIG. 6. FIG.

FIG. 9 is a graph showing the characteristics of the screw propeller of FIGS. 6-8.

FIG. 10 is a perspective view showing a screw propeller as a third embodiment of the present invention.

FIG. 11 is a side view of a conventional screw propeller.

FIG. 12 is a perspective view of the screw propeller of FIG. 11;

[Explanation of symbols]

1 Propeller blade 2 Propeller hub 3 Wing tip 4 Wing tip vortex 5 Propeller hub rear end 6 Hub vortex 7,7′,7″ Cut groove 8 End face in cut groove 8a Guide surface in cut groove

Claims (1)

[Claims] 1. A screw propeller, comprising a plurality of propeller blades protruding radially from a propeller hub, and a plurality of cut grooves are formed on a surface of the propeller hub.