JP2012162116A - Wave shock relieving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wave shock relieving device for relieving a shock received from a wave, by dispersing a flow of the wave received from below to the lateral rear, needless to say the wave from the front colliding with a bow part.SOLUTION: This wave shock relieving device 1 is arranged in a ship 5 having a breakwater wall extended forward on the upper side of the bow part 6 and a bow bulb arranged on the lower side of the bow part 6, and includes a wave dispersing member 2 having a dispersing surface 21 expansively opened over the rear end from the front and laterally dispersing the flow of the wave received from the front and continuously arranged over the bow bulb from the breakwater wall, and a wave deflecting member 3 arranged over a right side wall and a left side wall of the ship 5 from the dispersing surface 21 of the wave dispersing member 2 and changing the flow of the wave received from below to the lateral rear.

Description

  The present invention relates to a wave impact mitigation device provided at the bow of a ship equipped with a bow valve, and more particularly to a wave impact mitigation device suitable for a ship whose navigation is easily affected by waves such as small ships.

  Conventionally, a bow valve (also referred to as “Bulbous Bow”) formed in a hemispherical shape or the like on the lower side of the bow is provided in order to reduce the wave-making resistance generated when the ship sails. is there. This bow valve is for generating waves in front of the bow of the ship, and the waves generated by this bow valve interfere with the waves generated at the bow to cancel each other's waves. Thus, the generation of waves is suppressed and the resistance is reduced.

  However, in the actual sea area, not only when the sea surface is calm, there are cases where waves of various sizes are accompanied. In the sea area with waves on the sea surface, the waves collide with the bow of the navigating ship. The waves that collide with the bow are extremely strong in impact, have a large resistance to navigation, and have a problem that the hull may be damaged. Resistance, impact, and the like due to waves colliding with the bow cannot be reduced even by the bow valve.

  So far, several inventions have been proposed for reducing the resistance caused by waves that collide with the bow.

  For example, Japanese Patent Laid-Open No. 2004-314943 proposes a ship provided with a reflected wave reducing structure having a curved surface that smoothly contacts the hull near the water surface above the bow valve (Patent Document 1). According to this patent document 1, it is said that the reflected wave reduction structure can reduce the reflection of the wave at the bow by dividing the wave received from the front into left and right.

Japanese Patent Application Laid-Open No. 2010-95238 discloses a substantially triangular shaped appendage having an angle that is equal to or smaller than an angle at which two straight lines contacting the shoulder portion of the bow portion, and a support member for attaching the additional product to a position higher than the waterline of the hull. There has been proposed a device for increasing and reducing resistance in waves (Patent Document 2).
According to this Patent Document 2, it is possible to not only reduce resistance increase for waves received from the front but also reduce resistance to waves received from diagonally forward, and can be easily attached to an existing ship. Has been.

Japanese Patent Laid-Open No. 2004-314943 JP 2010-95238 A

  However, in the invention described in Patent Document 1, there is a problem that an area receiving lateral waves and cross winds in the lateral direction is increased by the reflected wave reducing structure, steering performance is reduced, and resistance is increased.

  The tonnage of a ship is stipulated in, for example, the “Act on the Measurement of the Tonnage of a Ship” and the like in Article 3 paragraph 1 of this law. Or any place within a ship that is enclosed by bulkheads or decks or covers. " The international total tonnage is defined by the total volume of the enclosed place (Article 4 (2)). Therefore, the appendage surrounding the bow like the reflected wave reduction structure of Patent Document 1 is regarded as a part of the ship, and increases the length of the ship and the total tonnage of the ship.

  The total tonnage of a ship is a standard for ship freight, insurance premiums, etc., and a large-scale modification is required to provide a reflected wave reducing structure without changing the total tonnage of an existing ship. In particular, with regard to fishing boats, most of the ships are designed to the limit of allowable tonnage due to restrictions such as fishing permits and safety inspections, and it is virtually impossible to change the total tonnage.

  In addition, in the invention described in Patent Document 2, since the appendage is provided only in a part above the bow valve, there is a problem that the resistance reduction effect cannot be exhibited when the hull moves up and down due to waves. is there.

  Further, the inventions described in Patent Document 1 and Patent Document 2 are provided for the purpose of reducing resistance to waves received from the front or obliquely forward. However, there is a problem that waves that are received from below due to waves and hulls moving up and down cannot be countered. Such waves received from below collide with the wave barrier of the bow (also referred to as “Bulwork”) and cause great resistance. Yes.

  Small boats such as fishing boats are strongly affected by waves and winds regardless of whether they are sailing or operating. In particular, since the bow moves up and down easily and synchronizes with the waves, when the bow drop timing and the wave rise timing are synchronized, an extremely large impact occurs. In addition, unlike a large vessel, in a small vessel, the wave breaking wall is formed so as to spread forward and in the left-right direction. For this reason, the resistance and the impact which a bow receives at the time of returning to a port with many loads and stormy weather become still larger.

  The present invention has been made in order to solve such problems, and receives waves from waves by dispersing the flow of waves received from below from the front as well as from the waves colliding with the bow. An object of the present invention is to provide a wave impact mitigation device for mitigating the impact.

  A wave impact mitigation device according to the present invention is a wave impact mitigation device provided on a ship having a wave barrier extending forward on the upper side of the bow and a bow valve provided on the lower side of the bow. A wave dispersion member that is spread from the front end to the rear end and has a dispersive surface that disperses the flow of waves received from the front to the left and right, and that is continuously provided from the wave barrier to the bow valve. And a wave deflecting member that is provided from the dispersion surface of the wave dispersion member to the right and left side walls of the ship and changes the flow of waves received from below to the left and right.

  Further, an impact avoidance gap for passing a transverse wave and a transverse wind may be formed between the rear end of the wave dispersion member and the hull.

  Furthermore, as one aspect of the present invention, the wave deflecting member may be provided above a full load water line of the ship.

  Furthermore, as one aspect of the present invention, the wave deflecting member may be provided in a plurality of stages in the height direction.

  According to the present invention, not only the wave from the front that collides with the bow, but also the flow of the wave received from below can be dispersed to the left and right and the shock received from the wave can be reduced.

It is a side view which shows the bow part of the ship which provided one Embodiment of the wave impact mitigation apparatus which concerns on this invention. It is a front view which shows the bow part of this embodiment. It is the 3A-3A sectional view taken on the line in FIG. About the wave dispersion | distribution member in this embodiment (a) One embodiment in which the front end edge is formed in the curve shape which swelled ahead, (b) The front end edge is formed in the curve shape which was dented in the back side. It is a side view showing one embodiment. Among the wave deflecting members in this embodiment, (a) one embodiment formed in a plate shape, (b) one embodiment in which the lower surface is formed in an inclined shape, and (c) the lower surface is curved upward. It is sectional drawing which shows one Embodiment formed in the curved surface form. It is a side view which shows one Embodiment which provided the wave deflection | deviation member in this embodiment in multiple steps in the height direction. 4 is a table showing test results in Example 1. It is a graph showing the relationship between the amplitude (Heave amplitude) of the vertical movement of a model ship based on the test result of Example 1, and the wavelength of the wave received from the front. It is a graph showing the relationship between the amplitude (Pitch amplitude) of the vertical vibration of a model ship and the wavelength of the wave received from the front based on the test result of the first embodiment. It is a graph showing the relationship between the resistance increase coefficient and the wavelength of the wave received from the front based on the test result of the present Example 1. It is a graph showing the relationship between effective horsepower and navigation speed based on the test result in Example 2.

  Hereinafter, an embodiment of a wave impact mitigation device according to the present invention will be described with reference to the drawings. FIG. 1 is a side view showing a bow portion 6 of a ship 5 provided with a wave impact mitigation device 1 of the present embodiment, and FIG. 2 is a front view thereof.

  The wave impact mitigation device 1 of the present embodiment is mainly composed of a wave dispersion member 2 that disperses a wave flow received from the front to the left and right, and a wave deflecting member 3 that changes the wave flow received from the lower side to the left and right and the rear. Has been. Hereinafter, each configuration will be described in detail.

  In the present invention, as shown in FIGS. 1 and 2, the ship 5 provided with the wave impact mitigation device 1 has a wave breaker wall 7 extending forward on the upper side of the bow part 6. A bow valve 8 for reducing wave resistance is provided below 6. The wave barrier 7 and the bow valve 8 are generally provided in the ship 5 and do not require any special configuration. The size and type of the ship 5 are not particularly limited, and may be a large ship or a small ship, or a tanker or a fishing boat.

  First, the wave dispersion member 2 will be described. The wave dispersion member 2 includes a dispersion surface 21 that is expanded from the front end to the rear end. The dispersion surface 21 is for dispersing the wave flow received from the front side to the left and right. As shown in FIG. 3, the wave dispersion member 2 in the present embodiment has a horizontal cross-sectional shape that is substantially triangular, and two surfaces that are formed symmetrically with respect to the center line of the ship 5 are the dispersion surfaces 21. Is configured. In addition, although the wave dispersion member 2 in this embodiment is formed in the shape of a triangular prism and the rear end side 22 is closed, it is not limited to this, and is formed in a V shape by a plate-like member. Then, the rear end face may be opened.

  As shown in FIGS. 1 and 2, the wave dispersion member 2 is formed in a continuous shape from the wave breaking wall 7 to the bow valve 8. The wave dispersion member 2 is configured as a continuous shape without being divided so as to be able to cope with waves of various water surface heights, because the water surface height changes in the bow portion 6 that moves up and down by waves. It is desirable that In the present embodiment, the front edge 23 of the wave dispersion member 2 is formed in a substantially straight shape from the wave barrier wall 7 to the bow valve 8 as shown in FIG. 1, but as shown in FIG. It may be formed in a curved shape bulging forward or curved backward. Moreover, the shape of the front end edge 23 may be sharpened at an acute angle, or may be curved into a curved surface.

  Further, as shown in FIGS. 1 and 3, an impact avoidance gap 4 is formed between the rear end side 22 of the wave dispersion member 2 and the hull 51 so that a transverse wave and a transverse wind can pass through. The impact avoidance gap 4 is for avoiding a lateral impact received from a transverse wave and a transverse wind. The size and shape of the impact avoidance gap 4 are the shape and size of the ship 5 so as to minimize the area that receives the transverse waves and crosswinds while maintaining the function of dispersing the waves received from the front by the wave dispersion member 2. It is appropriately selected according to the above.

  Next, the wave deflecting member 3 will be described. As shown in FIG. 1 to FIG. 3, the wave deflecting member 3 is for changing the direction of the wave received from below and exchanging impact force, and from the dispersing surface 21 of the wave dispersing member 2 to the right side of the ship 5. It is provided over the wall 52 and the left side wall 53. The lower surface side 31 of the wave deflecting member 3 is a portion that receives waves from below. The wave deflecting member 3 may be formed in a plate shape as shown in FIG. 5 (a), or the lower surface side 31 of the wave deflecting member 3 is shown in FIG. 5 so as to easily change the flow of waves received from below. It may be formed in an inclined shape as shown in (b) or a curved shape curved upward as shown in FIG.

  Further, as shown in FIG. 1, the wave deflecting member 3 in the present embodiment is slightly inclined backward and downward, but is not particularly limited, and the wave flow received from below is redirected backward. The angle may be inclined substantially horizontally or rearward and upward.

  In addition, as shown in FIG. 3, the portion where the shock avoidance gap 4 between the left and right wave deflecting members 3 is formed has a gap so that waves and winds can pass through in the vertical direction.

  The wave deflecting member 3 is preferably provided at a position higher than the full load water line in order to prevent itself from becoming resistance during navigation. Further, as shown in FIG. 6, the wave deflecting member 3 may be provided in a plurality of stages so that the wave changing function can be exhibited even if the water level increases or decreases.

  Next, the operation of each component of the wave impact mitigation device 1 according to this embodiment will be described.

  When sailing on a ship 5 provided with the wave impact mitigation device 1 of the present embodiment, the wave dispersion member 2 disperses the wave flow received from the front by the dispersion surface 21 to the left and right. The dispersed wave flow flows along the dispersion surface 21 toward the right rear and left rear of the bow portion 6. Therefore, the wave dispersion member 2 can mitigate the impact received by the bow 6 due to the waves received from the front.

  Further, since the wave dispersion member 2 is continuously provided from the wave barrier 7 to the bow valve 8, even if the bow portion 6 moves up and down due to the wave and the water surface position changes, it flows from the front. Can receive waves over a wide area and disperse to the left and right.

  Further, since the wave dispersion member 2 is dispersed to the left and right with respect to the wave pressed from above the bow valve 8, it can be exposed on the water surface while avoiding the sinking of the bow valve 8. It is possible to reduce the resistance that is pressed from above that 8 has received.

  On the other hand, the impact avoidance gap 4 is reduced by passing through the impact received by the wave dispersion member 2 when the ship 5 receives a transverse wave or a transverse wind. That is, by forming a passage of a transverse wave or a transverse wind, the impact received by the wave dispersion member 2 can be reduced, the deterioration of the steering performance due to the provision of the wave dispersion member 2 can be prevented, and the rollover can be avoided.

  In addition, by providing the impact avoidance gap 4, the wave dispersion member 2 is handled as an addition to the ship 5. That is, the volume of the wave dispersion member 2 does not need to be the volume amount of the ship 5. Therefore, the volume of the ship 5 can be designed widely.

  The wave deflection member 3 changes the flow of waves received from below. The wave deflecting member 3 on the right side of the bow 6 changes the flow of waves received from below to the right side. Similarly, the wave deflecting member 3 on the left side of the bow 6 changes the wave flow received from below to the left side. By forming the lower surface of the wave deflecting member 3 into an inclined shape or a curved surface that is convex upward, the wave flow received from below easily changes to the right or left.

  The wave deflecting member 3 changes part of the wave flow from below to the rear. The flow changed to the rear further becomes the thrust of the ship 5. Therefore, the wave deflecting member 3 can not only relieve the impact of the wave received from below, but also can convert part of the energy of the wave into thrust, thereby improving fuel efficiency.

  In addition, since the wave deflecting member 3 in the present embodiment is provided with a gap so that the shock avoidance gap 4 passes the waves and winds up and down, the influence of the transverse waves and the crosswinds can be minimized.

  Further, the wave deflection member 3 has a function of supporting the wave dispersion member 2. That is, it is possible to eliminate the strength shortage of the wave dispersion member 2 due to the provision of the impact avoidance gap 4 and firmly fix the wave dispersion member 2.

According to the wave impact mitigation device 1 of the present embodiment as described above, the following effects can be obtained.
1. The shock of the wave received from the front can be reduced.
2. While mitigating the impact of waves received from below, part of it can be used as thrust.
3. The influence of a transverse wave and a transverse wind due to the provision of the wave impact mitigation device 1 can be minimized.
4). By providing the impact avoidance gap 4, there is no need to change the draft line length of the ship 5, the wave impact mitigation device 1 can be handled as an addition, and there is no need to change the volume or tonnage of the ship 5. Therefore, it can be attached to the ship 5 having a volume limit.
5. In particular, in a small vessel such as a fishing boat, the vertical swing at the bow 6 can be effectively reduced.

  Next, Example 1 of the wave impact mitigation device according to the present invention will be described. In Example 1, a resistance reduction test for a ship using a wave impact mitigation device was performed using a long water layer in a fishing boat propulsion performance test building of the National Fisheries Research Center.

  The long water layer is a water tank having a length of about 130 m, and water having a depth of about 3.0 m is removed. In addition, the water tank is provided with a toll train that travels on the water tank and a wave making device that generates a wave from the terminal end of the water tank toward the starting end. This wave generator can generate a wave having an arbitrary wavelength λ.

  The model ship used in Example 1 is provided with a break wall and a bow valve at the bow, and has a shape imitating a fishing boat having a total length L of about 1.4 m and a width B of about 0.29 m. is doing. A wave impact mitigation device can be installed at the bow of the model ship.

  The wave impact mitigation device used in the first embodiment is only a wave dispersion member, and no wave deflecting member or impact avoidance gap is provided.

  This model ship will be installed on the Toei train while floating in the tank. The installation part is equipped with an instrument that measures the amplitude of the model ship's vertical motion (hereinafter referred to as “Heave amplitude”) and an instrument that measures the amplitude of the ship's vertical vibration (hereinafter referred to as “Pitch amplitude”). It has been.

  In the test, a wave generator generates a wave having a predetermined wavelength λ in the water in the aquarium, and the model ship is navigated by a toll train in the wave. ”And“ longitudinal swing amplitude ”were measured. The test conditions are as follows.

  First, the test was carried out for seven wavelengths λ. A value obtained by dividing the wavelength λ by the total length L of the model ship (hereinafter referred to as “wavelength ratio”) λ / L is 0.50, 0.75, 1.00, 1.25, 1.50, 2.00 and 3.00. Further, at each wavelength λ, two conditions were performed when the wave dispersion member was provided on the model ship and when it was not provided. Hereinafter, the measurement results will be described.

FIG. 7 shows the measurement results organized in a table. Each symbol in the table represents the following value. First, ξ ₃ is a value indicating the Heave amplitude of the model ship, and ξ ₅ is a value indicating the Pitch amplitude. Ζ _w is the amplitude of the incident wave, and K is the wave number of the wave.

Rtm is a value indicating the total resistance of the model ship. Raw is a value indicating the amount of resistance increase in the waves of the model ship. Furthermore, Kaw is a value indicating a resistance increase coefficient in the waves. Kaw is calculated by dividing Raw by the water density ρ, gravitational acceleration g, incident wave amplitude ζ _w ² and model ship width B ² , and multiplying by the total length L of the model ship.

  From the above, the resistance increase coefficient Kaw means that the smaller the value, the less resistance the model ship receives.

  In Example 1, the total resistance Rtm of the model ship (no wave dispersion member) on the flat water surface where no wave was generated by the wave making device was 1.183 (kgf).

8 and 9 are graphs of the measurement results of FIG. 7, and the vertical axis of FIG. 8 is obtained by making the Heave amplitude ξ ₃ dimensionless with the incident wave amplitude ζ _w . The vertical axis in FIG. 9 is obtained by making the Pitch amplitude ξ ₅ dimensionless with the wave number K and the incident wave amplitude ζ _w . Each horizontal axis represents the wavelength ratio λ / L.

  The Have amplitude rises from 0.5 to 2.0, with the wavelength ratio λ / L peaking at 2.0, and then falls gently. Comparing the difference in the Have amplitude due to the presence or absence of the wave dispersion member, the amplitude of the wave dispersion member tends to increase as the wavelength ratio λ / L increases.

  The pitch amplitude also increased as the wavelength ratio λ / L increased. Comparing the difference in pitch amplitude depending on the presence or absence of the wave dispersion member, the amplitude of the wave dispersion member tends to increase as the wavelength ratio λ / L increases, similar to the trend in the above Have amplitude.

  As described above, the difference in the Have amplitude and the Pitch amplitude due to the presence or absence of the wave dispersion member is considered to be due to the following reason. First, when there is no wave dispersion member, the wave received from the front covers the bow valve and presses the bow part from above, so the amplitude is considered to be small. On the other hand, when there is a wave dispersion member, the wave received from the front is dispersed right and left on the bow valve, so the force for pressing the bow part is weakened and the amplitude is considered to be increased.

  Next, the following results were obtained regarding the reduction in resistance due to the presence or absence of the wave dispersion member.

  FIG. 10 is a graph showing the relationship between the resistance increase coefficient Kaw and the wavelength λ, where the vertical axis represents the resistance increase coefficient Kaw and the horizontal axis represents the wavelength ratio λ / L.

  The resistance increase coefficient Kaw increases from 0.5 to 1.5 with the wavelength ratio λ / L peaking at 1.5, and then decreases. Therefore, it can be seen that the increase in resistance to the model ship in Example 1 has a certain peak value.

  Next, the difference in the resistance increase coefficient Kaw depending on the presence / absence of the wave dispersion member will be examined. As shown in FIG. 10, when the wavelength ratio λ / L is in the range of 0.5 to 2.0, the resistance increase coefficient Kaw is smaller when the wave dispersion member is provided. That is, it means that the resistance received by the model ship is reduced by providing the wave dispersion member, and the difference due to the presence or absence of the wave dispersion member is particularly noticeable in the range where the resistance increase coefficient Kaw becomes the largest.

  One of the reasons why the resistance is reduced is that the waves received from the front by the wave dispersion member are dispersed, so that the impact received by the bow portion is alleviated and thus the resistance is reduced.

  As another reason, considering the above-mentioned measurement results of the Have amplitude and the Pitch amplitude, the time for the bow valve to stay on the water surface becomes longer due to the provision of the wave dispersion member, and the water pressure received from above is reduced. This is thought to reduce the resistance of the model ship.

  In the case where the wavelength ratio λ / L is 3.0, the difference in the resistance increase coefficient Kaw depending on the presence or absence of the wave dispersion member was not so much seen. This is because when the wavelength ratio λ / L is 3.0 or more, the wave approaches the flat water surface, so that the increase in resistance due to waves is small regardless of the presence or absence of the wave dispersion member. Therefore, the data at the wavelength ratio λ / L of 3.0 does not deny the resistance reduction by the wave dispersion member in the ship traveling in the waves.

  As described above, in the first embodiment, it has been found that the resistance received by the ship can be reduced by reducing the waves colliding with the bow by the wave dispersion member of the wave impact mitigation device.

  Further, in Example 2, a prototype ship in which a bow valve and a wave dispersion member are not provided at the bow on a flat water surface where waves are not generated by the wave generator, and a bow valve provided on the prototype ship; The effective horsepower of a prototype ship with a bow valve and wave dispersion member was measured and compared.

  FIG. 11 is a graph showing the measurement results in the second embodiment. The vertical axis represents the effective horsepower (EHP), and the horizontal axis represents the navigation speed in knots.

  When comparing the effective horsepower at a navigation speed of 10.4 knots, when the bow was installed on the prototype ship, the effective horsepower decreased by about 20% compared to the prototype ship alone. That is, it has been found that an improvement in fuel efficiency of about 20% is expected.

  In addition, when the prototype ship was provided with the bow valve and the wave dispersion member, the effective horsepower was reduced by about 25% compared to the prototype ship alone. Therefore, the wave dispersion member can reduce the effective horsepower by about 5% even on the flat water surface than when the bow valve is provided, and the fuel efficiency can be further improved as compared with the case where the bow valve is provided. all right.

  The wave impact mitigation device according to the present invention is not limited to the above-described embodiment, and can be changed as appropriate.

  For example, the wave impact mitigation device may be configured to be detachable or may be provided in addition to an existing ship.

DESCRIPTION OF SYMBOLS 1 Wave impact mitigation device 2 Wave dispersion member 3 Wave deflection member 4 Impact avoidance gap 5 Ship 6 Bow portion 7 Wave breaker wall 8 Bow valve 21 Dispersion surface 22 Rear end side 23 Front end edge 31 Lower surface side 51 Hull body 52 Right side wall 53 Left side wall

Claims (4)

A wave impact mitigation device provided on a ship having a wave barrier extending forward on the upper side of the bow and a bow valve provided on the lower side of the bow,
A wave dispersion member that is spread from the front end to the rear end and has a dispersion surface that disperses the flow of waves received from the front to the left and right, and is provided continuously from the wave barrier to the bow valve;
A wave impact mitigating device comprising: a wave deflecting member that is provided from the dispersion surface of the wave dispersion member to the right side wall and the left side wall of the ship and changes a wave flow received from below to the left and right.   The wave impact mitigation device according to claim 1, wherein an impact avoidance gap for passing a transverse wave and a transverse wind is formed between a rear end of the wave dispersion member and the hull.   The wave impact mitigation device according to claim 1 or 2, wherein the wave deflection member is provided above a full-length draft line of the ship.   The wave impact reducing apparatus according to any one of claims 1 to 3, wherein the wave deflecting member is provided in a plurality of stages in the height direction.

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