JP4530505B2 - Ship stern flap device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stern flap device for a ship that reduces fuel consumption by improving the propulsion efficiency of a transom stern structure ship such as a ship.
[0002]
[Prior art]
Traditionally, ships have focused only on driving performance and not much on driving economy. In recent years, research has also been conducted on the economics of ship operation, that is, the reduction of fuel consumption. Naval Engineer Journal, March 1999 (P76-81) published such research results (Stern Flap Powering on a Spruance Class Destroyer; Ship Trials and Model Experiments). According to the above article, the effectiveness of the stern flaps has been confirmed by model tests and tests attached to actual ships. FIG. 2 is a side view showing a state in which the stern flap is attached. In the figure, 1 is a flap, 2 is a stern bottom, 3 is a transom, and 4 is a water surface. FIG. 3 is a photograph of a ship equipped with a stern flap. The top is taken from behind the stern, and the bottom is taken from obliquely below the flap. The size of the flap in this photo is 1.62m in length (about 1% of the length between the vertical lines of the ship (the length of the ship on the waterline)), and the width is 10.36m (equal to the transom width of the part where the flap is attached). The angle θ between the extension line of the bottom surface of the flap 1 and the stern bottom 2 (buttock) was 8.1 °. The effect of this flap 1 is that the driving power is reduced by 6 to 14% (ship speed) (11.7% on average), the maximum speed increase was 0.75 knots, fuel cost savings were $ 240,000 per year, and renovation costs were depreciable within one year.
[0003]
The effect of such a stern flap can be considered as follows. The water flow before the propeller at the stern bottom becomes slower, the water pressure near the propeller rises, and the propeller efficiency is improved. Furthermore, the cavitation of the propeller can be suppressed by increasing the water pressure. 2. Wave generation generated so as to rise from the transom stern is suppressed, and as a result, wave resistance is reduced. The wave resistance is reduced by extending the apparent captain. The force to push up the stern by 4 flaps works, and it becomes a bow trim that the bow side falls slightly. As a result, the surface area of the ship below the waterline is reduced and resistance is reduced.
[0004]
[Problems to be solved by the invention]
Ships, especially ships, sail at various speeds from low to medium, but since the flap is fixed, the angle between the extension line of the flap bottom and the stern bottom (hereinafter referred to as the flap angle) is fixed at a certain sailing speed. Even if it is optimal, it will not be at the optimal angle at other navigation speeds, and in extreme cases, the disadvantage will be greater than the advantage of attaching the flap.
[0005]
The present invention has been devised in view of such problems of the prior art, and controls the flap angle in accordance with the navigation speed so that the maximum merits of the flap can be enjoyed for every navigation speed of the ship. The purpose is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a stern flap device for a ship according to the present invention has a flap pivotally attached to a submerged lower end of a transom of a transom stern structure, and a stern bottom transom side of the bottom of the flap by a swing mechanism. The inclination angle with respect to the lower surface of the is controlled.
[0007]
It is preferable to divide the flap into left and right at the hull center line and control the inclination angle independently.
[0008]
Next, the operation of the present invention will be described. When the ship navigates at a low speed, the flap becomes a resistance, and the disadvantage is greater than the advantage. Therefore, at low speed, the flap angle θ is set to 0 ° so that only the advantages 2 and 3 are obtained. When the ship is sailing at medium and high speeds, all the advantages 1 to 4 above can be obtained by angle the flap. The optimum flap angle corresponding to the navigation speed of the ship can be easily obtained by measuring the actual ship.
[0009]
By dividing the flaps to the left and right and controlling the flap angles independently, different lifts are generated on the left and right by the water flow during navigation of the ship, so that the roll of the ship can be attenuated. For example, when the ship is tilted to starboard, if the lift is generated by making an angle only on the starboard side flap, the inclination of the ship can be suppressed. Also, if the flap angle is controlled to be different from left to right, the left and right drag will be different, so the ship will turn left or right. Therefore, it can be a substitute for a rudder.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a state in which a stern flap device for a ship according to the present invention is attached to a ship, (A) is a side view, and (B) is a plan view. In this figure, the same reference numerals are given to the parts common to FIG. 2 used for explaining the conventional example. In the figure, reference numeral 2 denotes a stern bottom, which is inclined slightly upward toward the rear. A transom 3 is a vertical surface of the stern part. 4 is a water surface and 5 is a hull. Reference numeral 6 denotes a propeller, which may be one or two arranged horizontally. 7 is a rudder.
[0011]
Reference numeral 8 denotes a flap that can swing up and down. The base end of the flap 8 is pivotally attached to the lower end of the transom 3 by a hinge 8c so that there is no step between the lower surface of the flap 8 and the lower surface of the stern bottom on the transom 3 side. The lower end of the transom 3 is submerged, and the base end of the flap 8 is also submerged. Reference numeral 9 denotes a hydraulic cylinder as an example of a swinging mechanism. The base end of the cylinder 9 is pivotally attached to the transom 3, and the tip of the piston is pivotally attached to the upper surface of the flap 8. As shown by the arrow 8, the rocker 8 swings up and down so that the flap angle θ can be controlled.
[0012]
One flap 8 may be provided, but it may be divided into left and right at the hull center line 10 as shown in FIG. The right side of the traveling direction is 8a, and the left side is 8b. The flap angles of the left and right flaps 8a and 8b can be controlled independently.
[0013]
Next, the operation of this embodiment will be described. When the ship 5 navigates at a low speed, the flap 8 becomes a resistance, and the demerit is larger than the merit. Therefore, at low speeds, the flap angle θ is set to 0 °, and among the four merits of the flap 8, the wave-making resistance is reduced by suppressing the wave-making that rises from the 2 transom stern. Only a reduction in wave resistance due to the extension of the three apparent captains is obtained.
[0014]
When the ship 5 sails at medium and high speeds, the flap 8 is angled, so that all the advantages mentioned above are obtained: “1 The water flow before the propeller 6 at the stern bottom 2 becomes slower and the water pressure near the propeller 6 This increases the efficiency of the propeller 6. Further, the cavitation of the propeller 6 can be suppressed by increasing the water pressure.2 The wave generation generated so as to rise from the transom stern is suppressed, and as a result, the wave resistance is reduced. (3) The apparent length of the captain is extended to reduce the wave resistance. , Resistance is reduced. ”
[0015]
The optimum flap angle θ corresponding to the navigation speed of the ship can be easily obtained by actual ship measurement.
[0016]
By dividing the flap 8 into left and right and independently controlling the flap angles, different lifts are generated in the left and right flaps 8a and 8b by the water flow during the navigation of the ship 5, so that the roll of the ship 5 is attenuated. Can do. For example, when the ship 5 is tilted to starboard, the tilt can be suppressed by generating lift with an angle only on the starboard side flap 8a. Further, when the flap angle θ is controlled so as to be different from right to left, the left and right drags are different, so the ship 5 turns left or right. Therefore, it can substitute for the rudder 7.
[0017]
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the invention.
[0018]
【The invention's effect】
As described above, the stern flap device of the present invention makes it possible to control the flap angle and select the optimum flap angle corresponding to the navigation speed of the ship, so that the fuel consumption is further reduced than the fixed flap. It is possible. Further, if the left and right flap angles are controlled separately, rolling of the ship can be suppressed.
[Brief description of the drawings]
1A and 1B are views showing a state in which a stern flap device of the present invention is attached to a ship, where FIG. 1A is a side view and FIG. 1B is a plan view;
FIG. 2 is a cross-sectional view showing a state in which a conventional stern flap is attached.
FIG. 3 is a photograph of a ship equipped with a conventional stern flap, with the top viewed from the rear and the bottom viewed obliquely from below.
[Explanation of symbols]
2 Stern bottom 3 Transom 8 Flap 9 Swing mechanism (hydraulic cylinder)

Claims (2)

A transom stern structure that has the same size and speed performance as a destroyer, and a flap is pivotally attached to the submerged lower end of the transom. The width of the flap is equal to the width of the bottom of the transom, and the length is about 1% of the length of the ship at the waterline. The ship's stern flap device is characterized in that the optimum flap angle for reducing the driving power can be selected in accordance with the navigation speed .   2. A stern flap device for a ship according to claim 1, wherein the flap is divided into left and right by a hull center line, and the inclination angle is controlled independently.

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