JP2010115971A - Monohull water jet propulsive ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monohull water jet propulsive ship capable of sufficiently absorbing slow flows in a boundary layer developed on a bottom part, and obtaining a high propulsive efficiency by wake gain in three or more monohull water jet propulsive ships. <P>SOLUTION: The monohull water jet propulsive ship 1 includes three or more water jet propellers, wherein an interval between an alongside side suction opening 4s arranged at the furthest alongside side for these water jet propellers and an alongside end 2b is 0-40% of the maximum breath Bi of the alongside side suction opening 4s. A plate-like wake acceleration member 5 is provided at the alongside side of the alongside side suction opening 4s, and a front end Pa of the wake acceleration member 5 is arranged at a position ahead of a front end Ia of the alongside side suction opening 4s by 25-60% of a hull waterline length Lwl. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a single-hull water jet propulsion ship equipped with three or more water jet propulsors, and more specifically, a flow having a slow flow velocity in a boundary layer developed along a wake promoting member provided at the bottom of the ship. The present invention relates to a single-body water jet propulsion ship that can obtain high propulsion efficiency due to wake gain by suction from a suction port.

  In a water jet propulsion ship equipped with a water jet propulsion device, water (or seawater) sucked from the bottom of the ship using a pump is jetted out from the nozzle at the rear to obtain propulsive force. .

  As shown in FIG. 5, the propulsive force of this water jet thruster is generally supplied to the suction port by ρ as the density of water, Q as the flow rate, Vj as the average flow velocity discharged from the nozzle, and Vj. When the momentum flow velocity, which is the average of the flow velocities, is Vm, the total thrust (gross thrust) Tg can be expressed by Tg = ρ × Q × (Vj−Vm). Here, the momentum flow velocity Vm is a product of the effective wake ratio (1-w) and the ship speed Vs, and is represented by Vm = (1-w) × Vs. Therefore, since Tg = ρ × Q × [Vj− (1−w) × Vs], the smaller the effective wake ratio (1−w), the larger the total thrust Tg.

  On the other hand, a boundary layer is generated on the bottom bottom surface of the water jet propulsion ship, and this boundary layer develops along the flow. In this boundary layer, the flow becomes slow, that is, the wake w becomes large and the effective wake rate (1-w) becomes small. Therefore, the slow flow in this boundary layer is sucked from the suction port. Thus, the effect of the wake w, that is, the high propulsion efficiency due to the wake gain can be obtained. In order to utilize this wake gain, a bottom space that can cover the suction width is secured in the lateral direction of the suction port, and the slow flow velocity in the boundary layer developed in this bottom space is sucked from the suction port. It is advantageous to do so.

  As shown in FIG. 6 when the ship bottom is looked up from the bottom, and FIG. 7 showing the relationship between the width of the suction port on the bottom of the ship and the range of the suction flow, the flow sucked by the suction port 4 of this water jet thruster (shown by the hatched portion) ) Fa to Fg suck the flows Fa to Fg from the range Bf wider than the width Bi of the suction port 4. When considering from low speed to high speed, the range Bf of the suction width for the water jet propulsion unit in the hull width direction is generally about 1.5 to 2.0 times the width Bi of the suction port 4.

  However, when considering three or more single-hull water jet propulsion boats as shown in FIGS. 8 and 9, the suction ports 4c and 4s occupy most of the bottom of the ship, so that a sufficient suction space is provided. It becomes difficult to secure. That is, it is not possible to secure the space 2c, 2i, 2s on the bottom of the ship sufficient to suck the boundary layer developed along the bottom 2 alongside the suction ports 4c, 4s. In particular, the suction port 4s on the most ship side is close to the ship side end 2b formed by a knuckle line, a chine line, or the like, and the width Bs is narrowed at the side portion 2s on the ship side of the suction port 4s. There arises a problem that the boundary layer developed on the bottom 2 other than the front of 4s cannot be sucked.

  With regard to the suction of water into the suction port of this water jet propulsion ship, a side fence with a length equal to or less than the intake length is attached to both sides of the opening of the intake (suction port) in parallel in the front-rear direction and flows into the intake. It has been proposed to improve the propulsion efficiency by reducing the pressure loss of the intake portion by regulating the flow to a smooth flow (see, for example, Patent Document 1).

  Also, in the water jet catamaran, in order to prevent air entrainment and suction during high-speed sailing, along both sides of the opening of the jet water intake port formed at the bottom of the left and right hulls along the bow-stern direction Intake with the intention of sufficient intake of seawater into the intake by preventing the increase in pressure loss resistance that occurs when the fence is suspended or the width of the bottom of the ship is approximately equal to the width of the intake (opening) It has been proposed to provide fin portions on both sides of the mouth in the horizontal direction to guide seawater to the water inlet (see, for example, Patent Documents 2 and 3).

However, these proposals all relate to pressure loss associated with vortex and entrainment flow, and are not intended for wake gain by sucking the flow in the boundary layer.
JP-A-7-112698 JP-A-6-329085 JP-A-8-324491

  The present invention has been made in view of the above-described situation, and its object is to achieve high propulsion with wake gain by sufficiently sucking a slow flow in the boundary layer in three or more single-body water jet propulsion vessels. An object of the present invention is to provide a single-hull water jet propulsion ship capable of obtaining efficiency.

  In order to achieve the above object, a single-hull water jet propulsion ship according to the present invention includes three or more water jet propulsion units, and a ship side suction port and a ship side which are arranged on the most ship side for these water jet propulsion units. In a single-hull water jet propulsion ship whose distance from the end is 0% to 40% of the maximum width of the ship side suction port, a plate-like wake promoting member is provided on the ship side of the ship side suction port At the same time, the front end of the wake facilitating member is arranged 25% to 60% ahead of the hull water line length from the front end of the ship side suction port. Here, the ship side end means a knuckle line or a chain line constituting the end of the ship bottom. In addition, the plate shape includes a double plate structure composed of a plurality of plate members. Further, the hull waterline length (Lwl) is the length of the surface of the water surface where the hull is stationary and immersed in water, and is the length of the hull measured on the draft surface.

  According to this configuration, the plate-like wake promoting member for developing a sufficient boundary layer is provided between the ship side suction port and the ship side end in the range of the flow sucked by the suction port (inlet). Therefore, this wake facilitating member can secure a space to compensate for the narrow space on the ship side of the ship side suction port, and the slow flow in the boundary layer generated and developed by this wake facilitating member can be secured at the ship side suction port. You will be able to inhale. As a result, high propulsion efficiency due to wake gain can be obtained.

  In particular, the boundary layer can be sufficiently developed by setting the length from the front end of the suction port to the front end of the wake promoting member to be 25% or more of the hull water line length (Lwl). Further, by setting the length from the front end of the suction port to the front end of the wake promoting member to be 60% or less of the hull water line length (Lwl), the adverse effect due to the increase in resistance becomes larger than the effect due to the development of the boundary layer. You can avoid that.

  In the single trunk water jet propulsion ship described above, the rear end of the wake promoting member is configured to be provided at least from the center in the front-rear direction of the ship side suction port to the rear. With this configuration, a slow flow in the boundary layer developed by the wake promoting member can be sufficiently sucked into the suction port.

  In the single-body water jet propulsion ship described above, the width of the wake promoting member is configured to be 25% to 80% of the maximum width of the ship side suction port. According to this configuration, a sufficient space in the horizontal direction of the hull can be secured by the ship bottom side of the ship side suction port and the portion by the wake promoting member, and the flow flowing into the suction port Can be a slow flow of.

  Further, if the width of the wake promoting member is made smaller than 25% of the maximum width of the ship side suction port, the space is insufficiently secured, and if it is larger than 80%, the portion of the wake promoting member that does not flow into the suction port. As a result, the adverse effect due to the resistance increase is greater than the wake gain effect. In view of structural strength and resistance performance, it is more preferably 50% or less.

  In the above-described single-hull water jet propulsion ship, the wake promoting member is configured to be provided in a knuckle portion or a chine portion of a hull. According to this configuration, it is possible to sufficiently use the ship bottom side of the ship side suction port for the development of the boundary layer, and to narrow the width of the wake promoting member.

  According to the single-hull water jet propulsion ship of the present invention, three or more water jet propulsion devices are provided, and the distance between the ship side suction port disposed on the most ship side for these water jet propulsion devices and the ship side end is the ship side. In a single-hull water jet propulsion ship that is 0% to 40% of the maximum width of the side suction port, a plate-like wake promoting member is provided on the ship side of the ship side suction port. Since the front end is configured to be 25% to 60% ahead of the hull water line length from the front end of the ship side suction port, the slow flow velocity in the boundary layer generated by this wake promoting member is Since suction can be performed at the side suction port, high propulsion efficiency due to wake gain can be obtained.

  Embodiments of a single-body water jet propulsion ship according to the present invention will be described below with reference to the drawings. As shown in FIG. 1 to FIG. 4, a single trunk “water jet propulsion ship 1, 1 </ b> A according to an embodiment of the present invention is configured to have a ship bottom 2 and a ship side 3, and further, four water A jet propulsion device (not shown) is provided, and four suction ports (inlets) 4c and 4s for the water jet propulsion device (not shown) are provided in the ship bottom portion 2.

  As shown in FIGS. 1 to 4, the suction ports 4 c and 4 s are composed of a center side suction port 4 c disposed on the hull center side and a ship side suction port 4 s disposed on the most ship side. Between the center side suction ports 4c and 4c is a center side ship bottom 2c, and between the center side suction port 4c and the ship side suction port 4s is an intermediate ship bottom 2i. A ship side ship bottom 2s is provided on the ship side of the ship side suction port 4s.

  The ship side ship bottom 2s is a portion provided between the ship side suction port 4s disposed on the most ship side for the water jet propulsion device and the ship side end 2b. Significantly, it is 0% to 40% of Bi. The ship side end 2b refers to a knuckle line or a chain line that constitutes the end of the ship bottom 2.

  In the present invention, the plate-like wake promoting member 5 is provided in the ship side ship bottom 2s portion which is relatively narrow and does not have a sufficient ship bottom space. The plate-like wake promoting member 5 includes a double plate structure constituted by a plurality of plate members.

  With respect to the arrangement of the wake promoting member 5 in the ship length direction, as shown in FIGS. 1 and 3, the front end Pa of the wake promoting member 5 has a hull water line length Lwl greater than the front end Ia of the ship side suction port 4s. 25% to 60% is arranged in front. This hull water line length Lwl is the length of the surface of the water surface where the hull is stationary and immersed in water, and is the length of the hull measured on the draft surface. Further, the rear end Pb of the wake promoting member 5 is provided at least behind the center Ic in the front-rear direction of the ship side suction port 4s.

With respect to the ship length direction, the boundary layer thickness δ at an arbitrary position x distant from the front end Pa of the wake promoting member 5 is δ = 0.37, where Vs is the ship speed and ν is the kinematic viscosity coefficient. × (ν / (Vs × x)) ^1/5 Calculated by × x.

  On the other hand, during high-speed voyage, as shown in FIG. 7, the flows Fa to Fg distributed at a depth Df (= 0.4 × Bi) of about 40% of the width Bi of the suction port 4s are sucked. This has been confirmed by experiments. In general, in order to ensure such a boundary layer thickness δ at the ship side suction port 4s, the wake promoting member 5 needs to have a length of at least 25% of the hull water line length Lwl. Therefore, the front end Pa of the wake promoting member 5 is disposed more than 25% of the hull water line length Lwl from the front end Ia of the ship side suction port 4s.

  With respect to the arrangement of the wake promoting member 5 in the hull width direction, in the configuration of FIGS. 1 and 2, the wake promoting member 5 extends along the length of the ship along the portion between the ship side suction port 4s and the ship side end 2b. Is provided. 3 and 4, the wake promoting member 5 is provided in the ship side end 2b along the ship length direction. Thus, if the wake promoting member 5 is provided on the ship side or the ship side end 2b, the effect of suppressing the roll of the ship can be achieved.

  Regarding the attachment angle of the wake promoting member 5, as shown in FIGS. 2 and 4, the wake promoting member 5 is set at an angle α of 5 to 50 degrees, more preferably 20 to 40 degrees with respect to the horizontal. Inclined so that the tip side is down. By setting the attachment angle α to 5 to 50 degrees, more preferably 20 to 40 degrees with respect to the horizontal, there is an effect that a slow flow can be more easily guided to the suction port 4.

  Since the plate-like wake promoting member 5 for developing a sufficient boundary layer in the suction range of the ship side suction port 4s is provided, the flow velocity in the boundary layer generated and developed by the wake promoting member 5 is slow. Since the flow can be sucked at the ship side suction port 4s, high propulsion efficiency due to the wake gain can be obtained.

  In particular, by setting the length La from the front end Ia of the ship side suction port 4s to the front end Pa of the wake promoting member 5 to be 25% or more and 60% or less of the hull water line length Lwl, the length of the wake promoting member 5 is increased. Is long enough to develop the boundary layer. Further, by setting the position of the rear end Pb behind at least the center Ic in the front-rear direction of the ship side suction port 4s, the slow flow in the boundary layer can be sufficiently sucked.

It is a top view of the stern part seen from the bottom which shows the structure of the single body water jet propulsion ship in embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line XX of FIG. 1 illustrating the configuration of the single-body water jet propulsion ship according to the embodiment of the present invention. It is a top view of the stern part seen from the bottom which shows the other structure of the single trunk water-jet propulsion ship in embodiment of this invention. It is XX transverse cross section of Drawing 3 showing other composition of a single body water jet propulsion ship in an embodiment of the invention. It is a figure which shows the relationship between the ship speed of a water jet propulsion ship, a momentum flow velocity, and an exit flow velocity. It is a top view which shows the suction state of the flow of the hull width direction around the suction inlet of a water jet propulsion ship. It is a cross-sectional view which shows the suction condition of the flow of the depth direction around the suction inlet of a water jet propulsion ship. It is a top view of the stern part seen from the bottom which shows the structure of the single body water jet propulsion ship for comparison with this invention. FIG. 9 is a cross-sectional view taken along the line XX of FIG. 8 showing a configuration of a single-body water jet propulsion ship for comparison with the present invention.

Explanation of symbols

1, 1A, 1X 3 or more single-body water jet propulsion ship 2 Ship bottom part 2b Ship side end 2s Ship side ship bottom 3 Ship side part 4 Suction port 4s Ship side suction port 5 Wake promotion member Bs Ship side suction port and ship side end Interval Bi The maximum width of the ship side suction port Ia The front end of the ship side suction port Ic The center of the ship side suction port in the front-rear direction Lwl The hull waterline length Pa The front end of the wake promoting member Pb The rear end of the wake promoting member

Claims (4)

  Three or more water jet propulsion devices are provided, and the distance between the ship side suction port disposed on the most ship side and the ship side end for these water jet propulsion devices is 0% to 40% of the maximum width of the ship side suction port. In the single-body water jet propulsion ship, a plate-like wake promoting member is provided on the ship side of the ship side suction port, and the front end of the wake promoting member is positioned more than the front end of the ship side suction port. A single-hull water jet propulsion ship, which is located 25% to 60% ahead of the hull water line length.   2. The single-hull water jet propulsion ship according to claim 1, wherein a rear end of the wake promoting member is provided from at least the center in the front-rear direction of the ship side suction port to the rear.   The single-body water jet propulsion ship according to claim 1 or 2, wherein a width of the wake promoting member is 25% to 80% of a maximum width of the ship side suction port.   The single-body water jet propulsion ship according to claim 1, 2 or 3, wherein the wake promoting member is provided in a knuckle part or a chine part of a hull.

Images