JPS62149598A - Marine counter propeller - Google Patents

Abstract

PURPOSE:To avoid tip vortex cavitation by inclining the wing tip part of a front propeller toward the rear stream side in order to incline the whole rear propeller toward the upper stream side. CONSTITUTION:A front propeller 6 and a rear propeller 8 are placed onto one rotary axis in order to be revolved in the opposit direction to each other. And, the part extending from a root part 7 by 0.8 length of the radius of the front propeller 6 is arranged at a right angle to the rotary axis and the part extending up to a wind tip therefrom is inclined rearward. Also, the whole rear propeller 8 is inclined forward rather than the surface vertical to the rotary axis. And, the diameter of the rear propeller projected or the surface vertical to the rotary axis is made to be smaller than that of the front propeller projected to the surface vertical to the rotary axis, and made to be greater than 0.9.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a system in which a front propeller and a rear propeller are arranged on one rotational axis, and the front propeller and the rear propeller are rotated in opposite directions. This invention relates to a contra-rotating propeller for ships that propels ships.

[Prior Art] A conventional marine counter-rotating propeller is explained with reference to FIG. It is being The front propeller [1 propeller B is a normal propeller with a right pitch and rotates clockwise, and the rear propeller C is a normal propeller with a left pitch and rotates counterclockwise to propel the hull a.

[Problems to be Solved by the Invention] In such a two-set reversing marine propeller, when the operating load is relatively high, a chip pordex occurs and flows out from the blade tip e of the front propeller b. ? The biting f interferes with the rear propeller C even if the diameter of the rear propeller C is made approximately 10% smaller than the diameter of the front propeller 6 in advance.

Due to the interference between the front propeller B and the rear propeller C, the small tip ski There is a risk that it will occur9.
As one of these measures.

Although it is conceivable to roughly reduce the diameter of the rear propeller C, this is not a 1q measure because it would lead to a decline in the performance of the entire 11f-l device of the ship.

The present invention aims to improve the performance of a marine counter-rotating propeller by making it possible to avoid such tip portex cavitation.

[Means for Solving the Problems] The present invention provides a two-handed reversible marine propeller in which a front propeller and a rear propeller are arranged on one rotational axis, and the front propeller and the rear propeller rotate in opposite directions. , the length from the blade root of the front propeller to approximately O18 of the radius is perpendicular to the axis of rotation, and the portion from the length of approximately 0.8 of the radius of the front propeller to the blade tip is the rear (
The diameter of the rear propeller is the diameter of the rear propeller when the rear propeller body is tilted forward (upstream) from a plane perpendicular to the axis of rotation, and the diameter of the rear propeller is projected at right angles to the axis of rotation. This is a contra-rotating marine propeller whose dimensions are smaller than the diameter of the front propeller projected perpendicularly to and larger than 0.9.

[Function] Even if the front propeller and the rear propeller are installed close to each other and these two propellers are operating under high load,
The rear propeller can avoid tip portex cavitation flowing out from the front propeller.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a front propeller rotation shaft, and 2 is a rear propeller rotation shaft. There is. Boss 4 is attached to front propeller rotation 1111, and boss 5 is attached to rear propeller rotation 1N12.
is attached, the blade root 7 of the front propeller 6 is fixed to the boss 4, the blade root 9 of the rear propeller 8 is fixed to the boss 5, and the front propeller 6 and the rear propeller 8 are connected to one another. They are lined up on two rotational axes 3.

The front propeller 6 and the rear propeller 8 rotate in opposite directions to propel the hull (not shown).

The front propeller 6 has a radius R of approximately 0.8R from the blade root 7.
The direction of the rake up to is perpendicular to the axis of rotation 3 (zero rake angle), and the radius of the front blade 1 is approximately 0.8 of the radius of the copella 6.
The part from the length position of R to the blade tip 10 is the rotation axis 3
Although it is perpendicular to , it is inclined backward (to the downstream side) at an angle θb.

The rear propeller 8 is at an angle of 0 with respect to a plane perpendicular to the rotation axis 3.
The entire structure is tilted forward (upstream). When the diameter of the front propeller 1 and propeller 6 is projected onto a plane perpendicular to the rotational axis 3 and the diameter of the propeller 6 is J: DF shown in FIG. 2, the rear propeller 8 is perpendicular to the rotational axis 3. The diameter of the rear propeller 8 projected onto the plane is 019DF<D8<D
F - 0.9 of the diameter DF of the front propeller 6
It is larger than the diameter D of the front propeller, but the size is within a smaller range than the diameter D= of the front propeller.

The diameter DA of the rear propeller 8 is the diameter D of the front propeller 6 =
Since it is slightly smaller than the lG of the front propeller 6
m10 and the blade tip 11 of the rear propeller 8 will be close to each other, but in this counter-rotating marine propeller, the front propeller 6
Even when the rear propeller 8 is operating at a high load level, tip portex cavitation flowing out from the blade Min of the front propeller 6 can be avoided. 1 Since the front propeller 6 and the rear propeller 8 rotate in opposite directions, the speed component in the rotational direction during the thrilapse 1 to ream behind the propeller can be converted to the rotational axis 3 direction, and the diameter of the rear propeller 8 Since the DA is also larger than the diameter of the rear propeller in a conventional two-set reversing propeller, it is possible to operate with a lower load than the conventional one.

[Effects of the Invention] In the end, the present invention not only provides high propeller recovery efficiency, but also reduces the possibility of small chips flowing out of the front propeller and causing erosion to the rear propeller. Biting can be avoided.

[Brief explanation of drawings]

FIG. 1 is a side view of an embodiment of the present invention, FIG. 2 is a view taken along the line ■--■ in FIG. 1, and FIG. 3 is a side view of a conventional marine two-handed reversible propeller. 3 is the rotation axis, 6 is the front propeller, 7 and 9 are the root parts, 8
is the rear propeller, 1o and ii are the wing tips.

Claims (1)

[Claims] 1) In a contra-rotating marine propeller in which the front propeller and the rear propeller are arranged on one rotational axis and rotate in opposite directions, the radius from the blade root of the front propeller is approximately 0. The length up to 0.8 is perpendicular to the rotation axis (zero rake angle), and the part from approximately 0.8 of the blade radius to the blade tip is tilted to the wake side, and , the entire rear propeller is tilted upstream from the plane perpendicular to the axis of rotation, and the diameter of the rear propeller projected onto the plane perpendicular to the axis of rotation is greater than the diameter of the front propeller projected onto the plane perpendicular to the axis of rotation. A counter-rotating marine propeller characterized by being small and having dimensions larger than 0.9.