JPH07108990A - 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 7 along the inner peripheral surface of the duct 3. A half-pocket type wall part 6a for converting a part of inflow pressure of the turning flow 7 into thrust is formed at the front edge part of the current plate 6.

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 the swirling flow is fixed to the straightening plate. In order to convert a part of the inflow pressure into a thrust force, a half-pocket type wall portion is formed at the front end portion of the flow straightening plate and is convexly bent and attached to the inner peripheral surface of the duct.

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 is immediately captured by a straightening vane inclined in the direction opposite to the inflow direction of the swirling flow and is converted into a backward flow, which is a half-pocket type formed at the front end of the straightening vane. Along with the fact that the wall portion converts a part of the inflow pressure of the swirling flow into a thrust, an action of efficiently converting the swirling energy in the wake of the propeller 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. The increase in maximum draft can be suppressed compared to the case where the duct is a cylindrical type, and moreover, the swirling energy in the wake of the propeller due to the half-pocket type rectifying plate with wall that is inclined and projected on the inner peripheral surface of the duct Is efficiently converted into thrust.

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.

A swirling flow 7 is formed at the front end of each straightening vane 6.
The mounting line 6b that is convexly curved on the inner peripheral surface of the duct 3 so that a part of the inflow pressure of the rectifying plate 6 can be converted into thrust.
A half-pocket type wall portion 6a attached through is formed. 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, and a half pocket formed at the front end portion of the straightening vanes 6. Along with the fact that the mold wall portion converts a 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 equipped with a ducted marine propeller according to the present invention. As shown in FIG. 4, a hook 8 provided at the stern and a locking member 9 on the aquarium wall.
When the thrust of the propeller 1 was measured by operating the drive device 2 in a state where the wire 11 including the coil spring type load cell 10 was connected between
In the case of the present invention provided with, it was possible to recognize an increase in thrust of about 36% 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 according to 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, the 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
Is provided so as to incline in the direction opposite to the inflow direction, and a half-pocket type wall portion 6a is formed at the front end portion of the current plate so as to be convexly curved and attached to the inner peripheral surface of the duct 3.

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 that 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 accurately collected and guided to the rear side, and the front end portion of the rectifying plate 6 is performed. The swirling energy in the upper half of the propeller wake is efficiently converted into thrust in combination with the action of converting the swirling flow inflow pressure into a part of thrust by the half-pocket type wall 6a.

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.

[0020]

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 inclined in the direction opposite to the inflow direction of the swirling flows and is converted into a backward flow, and the half-pocket type wall at the front end of the straightening vanes. The swirling energy in the wake of the propeller can be efficiently converted into thrust in combination with the effect of converting the swirling flow inflow pressure into thrust by the section. (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 compared to the case of the cylindrical type, and moreover, the swirling energy in the wake of the propeller is made more efficient by the half pocket type straightening plate with a wall that is inclined and projected on the inner peripheral surface of the duct. Can be converted to thrust well. (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 Rectifier plate 6a Half-pocket wall 6b Mounting line 7 Swirling 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 periphery 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 front end portion of the straightening vane is provided with the above-mentioned structure. A marine propeller with a duct, characterized in that a semi-pocket type wall portion is formed that is convexly curved and attached to the inner peripheral surface of the 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.