JPH07108991A - Marine propeller with duct - Google Patents

Abstract

PURPOSE:To allow the rotational energy of turning flow to be converted into thrust by catching turning flow specially along the inner peripheral surface of a duct, and guiding it backward regarding a marine propeller with the duct increasing thrust by covering a screw propeller with the duct. CONSTITUTION:The inner peripheral surface of a duct 3 extended backward after covering a propeller 1 loosely is provided with plural current plates 6 extended in the longitudinal direction of the duct 3. The current plates 6 are fitted being inclined retrorsely to the turning direction of turning flow 7 so as to be able to catch the turning flow along the inner peripheral surface of the duct 3. The front half part of the current plate 6 is formed into an easy protruding curved wall 6a for converting a part of the inflow pressure of the turning flow 7 into thrust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-rotation screw propeller mainly used for high-speed boats, and more particularly to a marine propeller with a duct having a duct for gently covering the propeller.

[0002]

2. Description of the Related Art In a conventional marine propeller with a duct, a plurality of fins for radially converting a rotational component in a wake of the propeller into a linear component are radially provided inside a duct that gently covers a high-rotation propeller. There are many things. (See JP-A-60-25884 as an example)

[0003]

By the way, in the case of the conventional marine propeller with a duct as described above, the fins have an airfoil cross section to convert the wake of the propeller into a straight flow. For a flow with a strong swirl component that occurs along the inner peripheral surface of the duct due to high rotation,
There is a problem that a sufficient rectifying action cannot be performed. The present invention is intended to solve such a problem, and a high-rotation type propeller gently covers the same propeller to cause a strong turning which tends to occur on an inner peripheral surface of a duct extending rearward. An object of the present invention is to provide a marine propeller with a duct in which a flow having a component is accurately captured and is forced to flow rearward to increase thrust.

[0004]

In order to achieve the above object, a marine propeller with a duct according to the present invention is a marine propeller having a plurality of propeller blades and rotated by a drive device, and gently covers the periphery of the propeller. And a duct extending rearward, and a plurality of straightening vanes projecting on the inner peripheral surface of the duct behind the propeller and extending in the longitudinal direction of the duct, the straightening vane being the propeller. In order to capture the swirling flow of the wake along the inner peripheral surface of the duct and guide the swirl to the rear, the swirling flow is fixed obliquely in the direction opposite to the inflow direction of the swirling flow, and In order to convert a part of the inflow pressure into thrust, the attachment line to the inner peripheral surface of the duct of the rectifying plate is gently bent in the first half of the duct in the opposite direction to the swirling direction of the swirling flow, First half of the current plate There has been characterized in that it is formed as a gentle convex curved wall projecting into the turning direction of the swirling flow.

Further, the marine propeller with a duct of the present invention is characterized in that the duct is formed in a substantially semi-cylindrical shape which gently covers the propeller from above.
Further, the marine propeller with a duct of the present invention is characterized in that the diameter of the duct and the width of the straightening vane are gradually reduced from the front end to the rear end.

[0006]

In the above-mentioned marine propeller with a duct of the present invention,
The swirling flow generated rearward from the propeller rotating at a high speed is suppressed by the duct from expanding toward the outer peripheral direction due to the centrifugal force, so that an extremely strong swirling flow tends to occur along the inner peripheral surface of the duct. However, the swirling flow was immediately captured by the straightening vanes inclined in the direction opposite to the inflow direction of the swirling flows and was converted into a backward flow, which was formed as a gentle convex curved wall of the straightening vanes. Combined with the fact that the first half part converts a part of the inflow pressure of the swirl flow into thrust,
The action of efficiently converting the swirling energy in the wake of the propeller into thrust is performed.

When the duct is a substantially semi-cylindrical type that covers the propeller from above, the semi-cylindrical type duct prevents the propeller wake from rising to the water surface in an outboard motor or the like mounted on a small boat. As compared with the case where the duct is a cylindrical type, the increase in maximum draft can be suppressed, and moreover, after the propeller is installed by the straightening vane that is projected on the inner peripheral surface of the duct with an inclination and the front half is formed as a gently curved wall. The action of efficiently converting the swirling energy in the flow into thrust is performed.

Further, when the diameter of the duct and the width of the straightening vane are formed so as to gradually decrease from the front end to the rear end, simultaneously with the conversion of the swirling flow into the linear flow, The above-mentioned duct and the current plate also perform the contraction action, whereby the thrust is further increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a marine propeller with a duct as a first embodiment, and FIG. 1 is a ship equipped with the marine propeller with a duct according to the present invention. 2 is a perspective view of the duct covering the marine propeller of FIG. 1 as seen obliquely from the front, and FIG. 3 is a perspective view of a model ship equipped with the marine propeller with the duct, and FIG. FIG. 5 is a side view showing an experimental procedure using the model ship, and FIG. 5 is a perspective view of a marine propeller with a duct as a second embodiment of the present invention as seen obliquely from the front.

First, the first embodiment of the present invention will be described. As shown in FIGS. 1 and 2, in a marine propeller 1 having a plurality of propeller blades 1a and rotated at a high speed by a drive unit 2, the circumference of the propeller 1 is shown. There is provided a duct 3 that gently covers and extends rearward. The duct 3 is firmly attached to the hull 5 with an appropriate support bracket 4.
A plurality of straightening vanes 6 are provided on the inner peripheral surface of the duct 3 rearward of the propeller 1, and the straightening vanes 6 are elongated so as to extend in the longitudinal direction of the duct 3.

In this embodiment, the propeller 1 rotates counterclockwise when viewed from the rear, but each straightening vane 6 captures the swirling flow 7 along the inner peripheral surface of the duct 3 which is the wake of the propeller 1 as described above. In order to be accepted, the duct 3 is attached to the inner peripheral surface of the duct 3 in a standing state in which the swirl flow 7 is inclined in the opposite direction to the inflow direction. That is, when the swirling flow 7 is captured by the straightening vane 6, the straightening vane 6 is forcibly guided backward.

The front half of each straightening vane 6 can convert a part of the inflow pressure of the swirling flow 7 into the straightening vane 6 into thrust.
It is formed as a gentle convex curved wall 6a protruding in the swirling direction of the swirling flow 7, and therefore, the attachment line 6b of the flow straightening plate 6 to the inner peripheral surface of the duct 3 is formed in the front half of the duct 3 so that It is formed to gently bend in a direction opposite to the turning direction. Further, the diameter of the duct 3 and the width of each straightening plate 6 are both formed so as to decrease from the front end to the rear end, whereby the wake of the propeller is subjected to a contraction action.

Since the marine propeller with a duct as the first embodiment of the present invention is constructed as described above, the swirling flow generated rearward from the propeller 1 rotating at a high speed is
Due to the centrifugal force, the duct 3 is prevented from expanding toward the outer peripheral direction, and an extremely strong swirl flow 7 along the inner peripheral surface of the duct 3 is about to be generated by the duct 3.
The swirling flow 7 is immediately captured by the straightening vanes 6 inclined in the direction opposite to the swirling inflow direction of the swirling flows and is converted into a backward flow, which is gently formed in the front half of the straightening vanes 6. Along with the convex curved wall 6a converting part of the inflow pressure of the swirling flow 7 into thrust, the swirling energy in the wake of the propeller can be efficiently converted into thrust.

Further, since the diameter of the duct 3 and the width of the rectifying plate 6 are formed so as to gradually decrease from the front end to the rear end, the swirling flow 7 can be converted into a straight flow. At the same time, the duct 3 and the flow straightening plate 6 also perform a contraction action, which has the effect of further increasing the thrust.

FIG. 3 shows a model ship provided with a marine propeller with a duct according to the present invention. As shown in FIG. 4, between a hook 8 provided at the stern and a locking member 9 on the aquarium wall, The propeller 1 is operated by operating the drive device 2 in a state where the wire 11 including the coil spring type load cell 10 is connected.
As a result of the measurement of the thrust force, in the case of the present invention equipped with the duct 3 with the current plate 6, it was possible to recognize the thrust force increase of about 35% or more as compared with the case where the duct 3 was not provided.

In the first embodiment, the diameter of the duct 3 and the width of the rectifying plate 6 are both reduced toward the rear, but these members 3 and 6 are both reduced. Even if it extends rearward without doing so, it is possible to obtain the effect according to the above-described embodiment.

Next, a marine propeller with a duct as a second embodiment of the present invention will be described. In an outboard motor or the like mounted on a small boat, as shown in FIG. 5, a duct 3 gently guides the propeller 1 from above. It is formed in a substantially semi-cylindrical shape so as to cover it. Then, on the inner peripheral surface of the duct 3, as in the first embodiment described above, a plurality of flow rectifying plates 6 are provided, and the swirling flow 7
Of the rectifying plate is provided so as to be inclined in the direction opposite to the inflow direction, and the front half of the rectifying plate has a gentle convex curved wall 6a on the inner peripheral surface of the duct 3.
Is installed as. That is, the attachment line 6b of the wall portion 6a to the inner peripheral surface of the duct 3 is gently bent in a direction opposite to the swirl inflow direction of the swirl flow 7.

As a result, when the propeller 1 is rotationally driven by a drive device (not shown), the semi-cylindrical duct 3 prevents the propeller wake from rising to the water surface, and the maximum draft is higher than when the duct 3 is cylindrical. Can be suppressed, and moreover, the swirling energy in the wake of the propeller can be efficiently converted into thrust by the rectifying plate 6 that is provided so as to be inclined on the inner peripheral surface of the duct.

That is, since the rectifying plate 6 is provided so as to be inclined so as to capture the swirling flow 7, the swirling flow 7 is properly collected and guided to the rear side, and the front half portion of the rectifying plate 6 is performed. The swirling energy in the upper half of the propeller wake is efficiently converted into thrust force in combination with the effect of converting the swirling flow inflow pressure into a part of thrust force by the gentle convex curved wall 6a. Further, by reducing the diameter of the duct 3 and the width of the rectifying plate 6 from the front end to the rear end as shown in the figure, it is possible to perform a contraction action and increase the thrust. Even if you do not want to reduce
The presence of the straightening vane 6 can bring about a considerable effect.

In each of the above-mentioned embodiments, the straightening plate 6 is
One side edge of the straightening vane 6 is attached to a line of intersection between the plane including the central axis of the duct 3 and the duct 3, and the one side edge of the straightening plate 6 is directed in the swirling direction of the swirling flow 7 with respect to the line of intersection. With a slight inclination, the swirl flow 7 to the inside of the current plate 6
A part of the inflow pressure may be converted into thrust.

[0021]

As described above in detail, according to the marine propeller with a duct of the present invention, the following effects can be obtained. (1) The swirling flow generated from the propeller rotating at high speed toward the rear is suppressed by the duct from expanding toward the outer peripheral direction due to the centrifugal force, so an extremely strong swirl flow is generated along the inner peripheral surface of the duct. However, the swirling flow is immediately captured by the straightening vanes that are inclined in the direction opposite to the inflow direction of the swirling flows, and is converted into a backward flow. The swirling energy in the wake of the propeller can be efficiently converted into thrust in combination with the action of the wall to convert the swirling flow inflow pressure into thrust. (2) When the duct is a semi-cylindrical type that covers the propeller from above, the semi-cylindrical duct prevents the propeller wake from rising to the water surface in an outboard motor equipped on a boat. It is possible to suppress the increase of the maximum draft as compared with the case of a cylindrical type, and moreover, the rectifier plate which is formed so as to be inclined on the inner peripheral surface of the duct and whose front half is formed as a gently curved curved wall causes the wake of the propeller wake. The turning energy in the inside can be efficiently converted into thrust. (3) The diameter of the duct and the width of the rectifying plate are formed so as to gradually decrease from the front end to the rear end, so that the swirl flow is converted into a linear flow at the same time, The duct and the flow straightening plate also perform the contraction action, whereby the thrust can be further increased.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a ship equipped with a marine propeller with a duct as a first embodiment of the present invention.

FIG. 2 is a perspective view of a duct that covers the marine propeller of FIG. 1 as seen obliquely from the front.

FIG. 3 is a perspective view of a model ship provided with a marine propeller with a duct.

FIG. 4 is a side view showing an experimental procedure using the model ship of FIG.

FIG. 5 is a perspective view of a marine propeller with a duct as a second embodiment of the present invention as seen obliquely from the front.

[Explanation of symbols]

 1 propeller 1a propeller blade 2 drive device 3 duct 4 bracket 5 hull 6 straightening plate 6a gentle convex curved wall 6b mounting line 7 swirl flow 8 hook 9 locking member 10 coil spring load cell 11 wire

Claims (3)

[Claims] 1. A marine propeller that has a plurality of propeller blades and is rotated by a drive device. The marine propeller includes a duct that gently covers the circumference of the propeller and extends rearward, and the inside of the duct behind the propeller. The rectifying plate is provided with a plurality of rectifying plates projecting on the peripheral surface and extending in the longitudinal direction of the duct, and the rectifying plate captures a swirling flow along the inner peripheral surface of the duct, which is a wake of the propeller, and guides it backward. Therefore, in order to convert a part of the inflow pressure of the swirl flow into the straightening vane into thrust, the duct inner peripheral surface of the straightening vane is fixed so as to be fixed in a direction opposite to the inflow direction of the swirling flow. The mounting line to the front part of the duct gently bends in the opposite direction to the swirling direction of the swirl flow, so that the front half of the straightening vane gently projects a curved wall protruding in the swirl direction of the swirl flow. Is formed as A characteristic marine propeller with a duct. 2. The marine propeller with a duct according to claim 1, wherein the duct is formed in a substantially semi-cylindrical shape that gently covers the propeller from above. 3. The marine propeller with a duct according to claim 1, wherein the diameter of the duct and the width of the straightening vane are gradually reduced from the front end to the rear end. A marine propeller with a duct.