JPH0719993Y2 - Ship with small stern wings - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a ship in which the stern end portion is formed to be substantially axisymmetric, and particularly to the flow flowing into a screw propeller provided behind the stern end portion, The present invention relates to a ship with a stern small wing designed to give a rotation component.

[Conventional technology]

2. Description of the Related Art Conventionally, there is a ship as shown in FIG. 2 (side view) as a ship whose hull shape at the stern end is substantially axisymmetric.

Behind such an axisymmetric stern end portion 1, a screw propeller 2 arranged concentrically with the central axis of the stern end portion 1 is adapted to operate, thereby propelling the hull. Be done.

The velocity distribution of the radial flow at the position of the screw propeller 2 of the ship described above is as shown in FIG.

[Problems to be solved by the device]

By the way, in the conventional ship as described above, while the screw propeller 2 is rotating, as shown in FIG. 2, a wing tip vortex 4 is generated from the wing tip of the propeller 2 and at the same time the hub 3 of the propeller 2 is rotated. Hub vortex 5 is generated from the tip.

Here, the rotation direction of the hub vortex 5 is the same as the rotation direction of the screw propeller 2, and the rotation direction of the blade tip vortex 4 is opposite to the rotation direction of the screw propeller 2.

In particular, in a ship having a stern end portion 1 having a shape close to that of a rotating body, as shown in FIG. 3, the speed near the hub of the propeller blade root is low, so that the degree of load on the propeller blade root increases, and FIG. A strong hub vortex 5 is generated as shown in FIG.

The hub vortex 5 only gives a rotational flow in the same direction as the propeller 2 to the propeller wake and does not contribute to an increase in propeller thrust. Therefore, the energy applied to generate the hub vortex 5 is not converted into thrust, and the propulsion efficiency is reduced.

Further, since the pressure is reduced in the central portion of the hub vortex 5, vortex cavitation called hub vortex cavitation 6 occurs, and the noise makes it impossible to use underwater acoustic equipment such as a research ship.

The present invention is intended to solve such a problem, and in order to prevent hub vortexes from being generated from the screw propeller disposed behind the stern end portion having a substantially axisymmetric shape, a screw propeller A small blade that gives a rotational component in the direction opposite to the rotational direction of the screw propeller to the flow that flows into the vicinity of the blade root is provided to improve propulsion efficiency.
An object of the present invention is to provide a vessel with stern winglets capable of preventing noise due to hub vortex cavitation.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a vessel with a stern winglet according to the present invention is formed such that the hull shape of the stern end portion is formed to be substantially axisymmetric, and a screw is provided behind the stern end portion and concentrically with its central axis. In a ship equipped with a propeller, on the outer periphery of the hull immediately before the screw propeller, a plurality of angles angled to twist the flow flowing into the vicinity of the blade root of the screw propeller in the direction opposite to the rotation direction of the screw propeller. Small blades are provided so as to project radially, and the length from the central axis to the tip of the small blade is set to 70% or less of the propeller radius of the screw propeller.

[Action]

In the above-described stern small winged ship of the present invention, the flow of the propeller blades of the screw propelling the stern propeller propelled by a plurality of small wings radially projected on the outer periphery of the stern end of the ship when the ship is traveling. It is twisted in the direction opposite to the direction of rotation near the root.

In this way, when the reverse flow flows into the blade root of the screw propeller, it cancels out the hub vortex generated from the screw propeller, so that the hub vortex disappears or is significantly reduced.

[Embodiment] A ship with stern winglets according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a stern side view of the stern, and the hull shape of the stern end 1 is formed to be substantially axisymmetric. In the constructed ship, a screw propeller 2 is provided behind the stern end 1 of the ship concentrically with the central axis A thereof.

Further, a plurality of angles α are attached to the outer peripheral portion of the hull immediately in front of the screw propeller 2 so as to twist the flow 8 flowing into the vicinity of the blade root of the screw propeller 2 in the direction opposite to the rotation direction of the screw propeller 2 (this embodiment). 4 blades 7 are provided, and these blades 7 are arranged so as to radially project from the axisymmetric position on the outer peripheral portion of the stern end portion 1.

The length r from the central axis A to the tip of each winglet 7 (protrusion length) is the propeller radius R of the screw propeller 2.
Is set to 70% or less.

Since the ship with stern winglets of the present embodiment is configured as described above, the screw propeller 2 is formed by the plurality of winglets 7 radially protruding from the outer peripheral portion of the stern end portion 1 immediately before the screw propeller 2. The flow inflowing into the screw propeller 2 is appropriately twisted in the direction opposite to the rotation direction of the screw propeller 2 near the blade root of the screw propeller 2.

Thus, when the reverse flow flows into the blade root portion of the screw propeller 2, the flow 8 along the outer peripheral surface of the hub 3
Are canceled by the hub vortex that is about to be generated from the screw propeller 2, and the hub vortex (see reference numeral 5 in FIG. 2) that should flow out from the rear end of the hub 3 disappears or is weakened. Vortex cavitation (second
(See reference numeral 6 in the figure) also disappears or is significantly reduced.

Therefore, the propulsion efficiency of the screw propeller 2 is improved, and the generation of noise due to hub vortex cavitation is prevented.

Particularly, in the vessel with stern winglets of the present invention, the above-mentioned protruding length r of each winglet 7 is set to 70% or less of the propeller radius R, so that each winglet 7 cancels the hub vortex. It works efficiently and can also prevent the generation of noise from the tip of the winglet 7 itself.

[Effect of device]

As described above in detail, the following effects and advantages are obtained by the ship with stern wing according to the present invention.

(1) Immediately before the screw propeller, a plurality of small blades twisting the flow in a direction opposite to the rotation direction of the propeller are radially projected on the outer periphery of the hull at the axisymmetric stern end,
Since the protruding length of each winglet is set to 70% or less of the propeller radius, the flow flowing into the screw propeller appropriately suppresses the generation of hub vortices near the hub.

(2) Since the generation of the hub vortex is suppressed by the above item (1), the hub vortex cavitation disappears,
Or it will be significantly reduced, and the above (1)
Since the term also prevents noise generation from the tip of the winglet,
Underwater audio equipment on research vessels can be used without any problems.

(3) Since the generation of the hub vortex is suppressed by the above item (1), the propulsion efficiency is significantly improved.

[Brief description of drawings]

FIG. 1 is a stern side view of a vessel with stern winglets as an embodiment of the present invention, FIG. 2 is a stern side view of a conventional vessel, and FIG. 3 is a flow velocity distribution chart at the propeller position of the conventional vessel. is there. 1 ... Stern end, 2 ... Screw propeller, 3 ... Hub, 4 ... Blade tip vortex, 5 ... Hub vortex, 6 ... Hub vortex cavitation, 7 ... Small wing, 8 ... Flow, A …
… Center axis, α …… Inclination angle.

Claims (1)

[Scope of utility model registration request] Claims: 1. A ship in which the hull shape of the stern end is formed to be substantially axisymmetric, and a screw propeller is provided rearward of the stern end concentrically with the central axis of the ship, immediately before the screw propeller. On the outer periphery of the hull, a plurality of small blades, which are angled so as to twist the flow flowing into the vicinity of the blade root of the screw propeller in the direction opposite to the rotation direction of the screw propeller, are radially projected, and the central axis line is formed. To the tip of the winglet is set to 70% or less of the propeller radius of the screw propeller, a vessel with stern winglets.