JP2006347519A - Device for enhancing propulsion performance for small craft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain the optimum propulsion performance by providing a skew of fins so as to change the water flow in the direction opposite to the propeller advancing rotational direction unless any other special reason exists in a device for reducing the hull vibration for a small craft in which a plurality of fins are radially expanded from a bossing in an upper area from a substantially just side of a propeller shaft in a forward area of the propeller, and the skew is provided on the fins so as to change the water flow in the same direction as or in the opposite direction to that of the advancing rotation (the rotational direction of the propeller when the hull is proceeding forward). <P>SOLUTION: In a device for enhancing the propulsion performance for a small craft, fins 15, 16 are installed only on a side from which a blade is raised during the propeller advancing rotation and on the ship center line, a rear edge having a wedge-shaped section is provided on a back side of a rear end of the fins, and the diameter of the fins is limited to be ≥ 60 to ≤ 110% of the diameter of the propeller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a propulsion performance improving device in a small boat.

FIG. 1 shows a stern side view of a conventional small boat. FIG. 2 is a cross-sectional arrow view taken along the line II-II in FIG. As shown in FIGS. 1 and 2, a conventionally devised propulsion performance improving device for a small boat is provided with a stern frame 2 at the rear end of the hull 1, and a boshing 3 at a substantially central portion in the vertical direction thereof. The propeller shaft 5 is rotatably provided through the bossing 3, and the propeller 4 is provided at the rear end thereof. In addition, the front end of the propeller shaft 4 is connected to a main engine installed onboard (not shown). A ladder horn 6 is provided above the stern frame 2, and a rudder 7 is provided on the ladder horn 6. Further, in the bossing 3, fins 8, 9, 10, 11, and 12 are respectively fixedly provided on the bossing 3 so as to protrude radially only from the upper side of the axis SL of the propeller shaft 5. In this case, the five fins 8, 9, 10, 11, and 12 can each change the flow of water in the direction opposite to the forward rotation direction of the propeller 4 (the rotation direction when the hull is traveling forward). A twist is applied. The five fins have different twist angles. DP in FIG. 1 represents the diameter of the propeller 4, CL in FIG. 2 represents the center line of the hull 1, SL represents a line perpendicular to the hull center line CL in the axis of the propeller shaft 5, and DF Represents the diameter of the fins 8, 9, 10, 11 and 12 (the diameter of the arc RF passing through the tip of the fin around the core of the propeller shaft 5).

Because the propulsion performance improving device for small ships (utility model No. 3093097, ship vibration reducing device) that has been devised in the past has been devised mainly for the purpose of reducing hull vibration by reducing propeller vibration force. The direction of twisting of the fins 8, 9, 10, 11, 12 is not particularly limited, and the twisting is such that the flow of water can be changed in the same direction as the forward rotation direction of the propeller 4 or in the opposite direction. Any device may be used, but in general, when not particularly limited, a device in which a twist is applied to change the flow of water in the direction opposite to the forward rotation direction of the propeller 4 is employed. When the hull in which the device is installed is traveling forward, the water flow at the stern part is changed to the direction opposite to the rotation direction of the propeller 4 by the action of the fins 8, 9, 10, 11 and 12, and the propeller 4 It is sent. As a result, if only the improvement of propulsion performance is described, the rotational flow (vortex flow in the same direction as the propeller rotation direction) generated behind the propeller 4 is reduced, so that the propulsion efficiency is improved by the reduced energy. As a countermeasure for the case where the so-called propeller pitch is too small and too light on the in-service vessel, a device with a twist to change the flow of water in the same direction as the forward rotation of the propeller 4 is adopted. Propulsion performance is reduced.

Problems to be solved by the invention

The above-described conventional device for improving the propulsion performance for small ships is a device mainly for obtaining a hull vibration reduction effect, and as described above, the twist of the fin is changed so as to change the flow of water in the direction opposite to the forward rotation direction of the propeller 4. In the case where the device is capable of obtaining the propulsion performance improvement effect at the same time, it is not necessarily an optimum device for obtaining mainly the propulsion performance improvement effect. Specifically, the fins 8, 9, 10, 11, and 12 of the conventional device have the fin diameter DF substantially the same as the propeller diameter DP as shown in (FIG. 1) and (FIG. 2). Two sheets are provided on the right and left sides of the boshing 3 and one on the hull center line CL. Further, although the cross-sectional shape of the fin is often considered to be a substantially streamlined shape, it has a problem that it cannot necessarily be said to be an effective device configuration.

Means to solve the problem

For this reason, the present invention has been proposed to obtain a propulsive performance improvement effect equivalent to that of the conventional device with a simple configuration with respect to a device whose main purpose is to improve the propulsion performance in the conventional device described above. The fin mounting position and quantity, the shape of the trailing edge of the fin, etc. are proposed, and the fin diameter is limited to 60% or more and 110% or less of the propeller diameter, and at least the propeller is rotated forward. It is characterized in that it is installed on the side where the propeller wing rises and on the center line of the hull, and further, a rear edge material having a wedge-shaped cross section is provided on the back side of the rear edge of the fin.

Hereinafter, a propulsion performance improving apparatus for a small boat according to a first embodiment of the present invention will be described with reference to the drawings. (FIG. 3) is a hull side view of the stern part, and (FIG. 4) is a sectional view taken along the line IV-IV in (FIG. 3). In the figure, the same reference numerals and symbols as those of the conventional ones indicate the same constituent members, and the description thereof will be omitted. When the propeller 4 is rotating forward, the fins 13 and 14 are installed so as to protrude from the boshing 3 at the shaft where the propeller blades are raised, the fin 16 is installed on the opposite side of the fin, and the fin 15 is installed on the hull center line CL. Has been. At that time, the fins 13, 14, 15, 16 are twisted to change the flow of water in the direction opposite to the forward rotation direction of the propeller 4. In the case of the present plan, as shown in FIGS. 3 and 4, the fins projecting almost directly to the side where the propeller blades descend when the propeller 4 is rotating forward are removed.

When the hull 1 in which the apparatus shown in the first embodiment is installed is traveling forward, the water flow at the stern part is changed in the direction opposite to the rotation direction of the propeller 4 by the action of the fins 13, 14, 15, 16. Since it is fed into the propeller 4, the rotational vortex in the same direction as the rotation generated behind the propeller 4 is reduced. Therefore, the propulsion efficiency is improved as much as the rotational vortex energy is reduced. According to the result of the inventor's investigation of propulsion performance in a tank test on a model by installing the device of the present plan in a tanker ship type having a length of about 125 m, the inventor found that the conventional device shown in (FIG. 1) and (FIG. 2) On the other hand, it was confirmed that the propulsion performance improvement effect was only reduced by about 1%. As described above, even if the fins projecting from the side of the heel side where the propeller blades descend when the propeller rotates forward from the conventional device are omitted, the propulsion performance improvement effect that is not much different from the conventional one is obtained. It is an effective device.

A second embodiment of the present invention will be described with reference to FIG. 5 and FIG. (FIG. 5) is a side view of the stern part, and (FIG. 6) shows a VI-VI cross-sectional arrow view in (FIG. 5). In the figure, the same reference numerals and symbols as those of the conventional ones are the same constituent members, and thus the description thereof is omitted. The fins 17 and 18 are installed overhanging from the bossing 3 on the side where the propeller blades rise when the propeller 4 rotates forward, and the fins 19 are installed on the hull center line CL. At that time, the fins 17, 18 and 19 are twisted so as to change the flow of water in the direction opposite to the forward rotation direction of the propeller 4. As described above, in the case of the present plan (FIG. 1) and (FIG. 2), the configuration is such that fins are not provided on the side where the propeller blades descend when the propeller 4 moves forward with respect to the conventional device shown in FIG. 2. Yes.

When the hull 1 in which the apparatus of the second embodiment of the present invention is installed is sailing, the flow of water at the stern part is changed in the direction opposite to the rotation direction of the propeller 4 and sent to the propeller 4. As a result, the rotational vortex generated behind the propeller 4 is reduced, and the energy corresponding to that amount is reduced, so that the propulsion efficiency is improved. The inventor installed the proposed device on a model ship in a tanker ship with a length of about 125m and conducted a survey on the improvement of propulsion performance by a water tank test. As a result, it was about 2.5% compared to the case where a conventional device was installed. The effectiveness of the present plan is shown by showing the performance of the decrease in the device, and it is an industrially effective device.

A third embodiment of the present invention is shown in FIG. 7 and FIG. (FIG. 7) is a figure for demonstrating the difference in a structure of a present Example, and shows the VII-VII cross section arrow sectional drawing of (FIG. 2), (FIG. 8) is also the same as VII- (FIG. 2). VII cross section arrow sectional drawing is shown. In the drawing of the sectional view of the conventional fin 9 (FIG. 7), the arrow indicates the direction of the flow, and the angle of attack indicates the angle of the flow hitting the fin 9. The back, front, front end, and rear end of the fin 9 are shown in the drawing. Further, the arrow and name display in the sectional view of the present invention (FIG. 8) are the same as described above. As shown in FIG. 8, the present proposal has a configuration in which a trailing edge member 20 is installed on the back side of the rear end portion of the conventional fin 9. The cross-sectional shape of the trailing edge member 20 has a wedge shape and is provided from the base to the tip of the fin.
The other fins 8, 10, 11, 12 are also provided with the trailing edge material 20 as in the case of the fins 9.

When the hull 1 in which the device composed of the fins provided with the trailing edge member 20 is installed is traveling forward, the flow of the stern part is changed in the direction opposite to the rotation direction of the propeller 4 by the action of the fins. Is sent to the propeller 4. Therefore, the rotational vortex generated behind the propeller 4 is reduced, and the propulsion performance is improved by an amount corresponding to the energy. The propulsion performance improvement mechanism in the small boat propulsion performance improvement device of the present invention is obtained by subtracting the energy component due to the increase in the specific resistance of the fin itself from the energy decrease effect component by reducing the rotational flow of the propeller wake. Since the specific resistance of the fin is reduced by the action of the trailing edge member 20, the propulsion performance is improved correspondingly.

In the fourth embodiment of the present invention, the fin diameter is limited. As for the direct DF of the fin shown in FIG. 2, the conventional one is configured substantially the same as the diameter DP of the propeller 4 as shown in FIG. 1, but with respect to the ratio of the fin diameter DF and the propeller diameter DP. A performance curve diagram showing the relationship of the propulsion performance improvement effect is shown in FIG. This performance chart shows the effect of improving the propulsion performance when the inventor installs a propulsion performance improvement device for a small ship with a tanker of about 125 m in length and the fin diameter DF is successively reduced in a tank test using a model ship. The results of the investigation are shown. According to it, the fin diameter DF is about 55% of the propeller diameter DP, and the propulsion performance improvement effect is almost zero, and in the region where the fin length is about 110% or more, there is almost no increase in the propulsion performance improvement effect. Has been. As described above, the mechanism of the propulsion performance improvement effect by this device is the improvement of the propulsion performance due to the reduction of the rotating vortex behind the propeller by the fin, minus the energy of the increase in the specific resistance of the fin. If the diameter DF of the fin is reduced, the effect of reducing the rotating eddy current is reduced, but the specific resistance of the fin is also reduced. Therefore, the effect is obtained even in a region where the diameter DF of the fin is relatively small. Further, in the region larger than the propeller diameter DP, almost no increase in the rotational flow reduction effect is observed, and only the fin specific resistance tends to increase, so a performance curve as shown in FIG. 9 is obtained. Accordingly, the effective fin diameter DF of the present apparatus is 60% to 110% of the propeller diameter DP.

The invention's effect

As described above, the propulsion performance improving device for small ships of the present invention has a relatively simple configuration compared to the conventional device, thereby providing a device that does not have the same or large performance degradation as the conventional device, and further If the edge material is applied, there is a great merit such that the same or better propulsion performance improvement effect is obtained, and an industrially very effective device is provided.

These are the side views of the stern part of the conventional small ship propulsion performance improvement apparatus. FIG. 2 is a sectional view taken along the line II-II in FIG. These are side views of the stern part of the first embodiment of the present invention. [Fig. 4] is a sectional view taken along the line IV-IV in Fig. 3. These are the side views of the stern part of 2nd Example of this invention. (FIG. 5) is a sectional view taken along the line VI-VI in FIG. These are the VII-VII cross-sectional arrow views of the conventional thing (FIG. 1). These are the VII-VII cross-sectional arrow views of (FIG. 1) showing the 3rd Example of this invention. These are the curve diagrams showing the performance regarding 4th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hull 2 Stern frame 3 Boshing 4 Propeller 5 Propeller shaft 6 Ladder horn 7 Rudder 8 Fin 9 Fin 10 Fin 11 Fin 12 Fin DP propeller diameter DF Fin diameter RF Fin tip rotation locus 13 Fin 14 Fin 15 Fin 16 Fin 17 Fin 18 Fin 19 Fin 20 Trailing edge material

Claims (1)

A plurality of fins projecting radially from the boshing are provided in front of the propeller from approximately right to the upper side of the propeller shaft center, and the fins have a direction opposite to the so-called propeller forward rotation, which is the propeller rotation direction during forward traveling of the hull. In the propulsion performance improving apparatus for small boats that is twisted to change the flow of water, the fins are provided only at least on the shore side where the wings rise during propeller forward rotation and on the hull center line, and A trailing edge member having a wedge-shaped cross-sectional shape is provided on the rear side of the rear end of the fin, and the diameter of the fin is limited to 60% or more and 110% or less of the propeller diameter.

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