JP5002378B2 - Marine propulsion efficiency improvement device and its construction method - Google Patents

Description

  The present invention relates to a marine vessel propulsion efficiency improving apparatus applied to a marine vessel including a propeller that generates thrust, and a construction method thereof.

Conventionally, as this type of technology, many devices having a plurality of fins arranged so as to be positioned on the bow side of the propeller are known (see Patent Documents 1 to 6). Among these marine propulsion efficiency improving devices, in the marine vessel propulsion performance improving device described in Patent Document 1, when the propeller rotates in the direction to advance the marine vessel, fins arranged on the side where the propeller blades descend are provided on the propeller shaft. On the other hand, fins provided on the trailing edge rising side and provided on the side where the propeller wing rises when the propeller rotates in the direction of advancing the ship are provided on the trailing edge descending with respect to the propeller shaft. A mounting angle with respect to the shaft is set to be large from the fin base toward the tip. Further, in the reaction fin of a ship described in Patent Document 2, in order to suppress the generation of vortices from the tip of the fin blade, the tip of each fin blade receives an incoming water flow compared to other portions. It is twisted to reduce the corners. Furthermore, in the reaction fin of the ship described in Patent Document 3, a flat plate member is fixed to the tip of each fin blade so as to cross the fin blade in order to suppress the vortex from the tip of the fin blade. Has been. Moreover, in the reaction fin of the ship described in Patent Document 4, in order to further improve the propulsion efficiency, the thickness of the fin disposed on the side where the propeller blades descend is increased when the propeller rotates in the direction of moving the ship forward. It is made thinner than the thickness of the fin on the side. Furthermore, in the reaction fin of the ship described in Patent Document 5, the length from the propeller shaft center to the blade tip of each fin is substantially the same as the propeller radius in order to further improve the propulsion efficiency. The ship vibration reducing device described in Patent Document 6 has a plurality of fins attached to the stan frame or the bossing so as to be located in a region in front of the propeller and above the propeller shaft center.
Japanese Examined Patent Publication No. 62-016878 Japanese Utility Model Publication No. 61-109898 Japanese Utility Model Publication No. 61-098698 Japanese Utility Model Publication No. 60-127299 JP 05-185986 A Registered Utility Model No. 3093097

  As described above, according to the marine vessel propulsion efficiency improving apparatus composed of a plurality of fins (hereinafter referred to as “stator fins”) fixed to the hull, the stator fin converts the flow of fluid to the propeller in the direction opposite to the propeller rotation direction. As a result, the propulsion efficiency of the ship can be improved. However, in order to apply the marine vessel propulsion efficiency improving apparatus as described above to a relatively large vessel, there are the following problems. That is, in order to improve the propulsion efficiency, as in the technique described in the above-mentioned Patent Document 5, the span of the stator fin (so that the length from the propeller shaft center to the blade tip of each fin is substantially the same as the radius of the propeller. It is preferable to increase the length from the root portion to the fin blade tip. However, since the outer diameter of the propeller is large in a large vessel, it is difficult to sufficiently secure the stator fin itself and its mounting strength. In this case, in order to ensure strength, it may be possible to manufacture a plurality of stator fins as an integral casting. However, this increases the construction cost of the marine vessel propulsion efficiency improvement device.

  Accordingly, the main object of the present invention is to provide a marine vessel propulsion efficiency improving apparatus that can be easily constructed at low cost and is suitable for a relatively large vessel.

  The marine vessel propulsion efficiency improving apparatus according to the present invention adopts the following means in order to achieve the above-mentioned main object.

The marine vessel propulsion efficiency improving apparatus according to the present invention is
A marine vessel propulsion efficiency improvement device comprising a plurality of stator fins radially disposed so as to be located on the bow side of the propeller with respect to a hull of a ship including a propeller that generates thrust,
The plurality of stator fins are formed such that when attached to the hull, the length from the propeller shaft center to the fin wing tip is 70% or less of the radius of the propeller, and When the angle between the plane including the edge and the propeller axis and the plane including the chord on the cross section of the root portion of the stator fin and the fin trailing edge is defined as the mounting angle of the stator fin, the mounting The gist is to be arranged in the hull so that the angle is 20 ° to 40 °.

  In this marine propulsion efficiency improving apparatus, the plurality of stator fins are formed such that the length from the propeller shaft center to the fin blade tip is 70% or less of the propeller radius when attached to the hull. The plurality of stator fins have an angle formed between a plane including the fin trailing edge of the stator fin and the propeller axis and a plane including the chord and the fin trailing edge on the cross section at the root portion of the stator fin. When the mounting angle is set, the mounting angle is set to 20 ° to 40 ° on the hull. In this way, if a plurality of stator fins are formed so that the length from the propeller axis to the fin blade tip is 70% or less of the propeller radius when attached to the hull, the blades from the root portion of each stator fin to the blades. Since the length to the end is relatively short, the strength of each stator fin itself can be sufficiently secured. In addition, even if each stator fin is fixed to the hull by welding or the like, the mounting strength of each stator fin to the hull can be sufficiently secured, and the marine vessel propulsion efficiency improving device can be easily and inexpensively installed on the ship. It becomes possible. Further, the angle between the plane including the fin trailing edge of the stator fin and the propeller axis and the plane including the chord and the fin trailing edge on the cross section in the root portion of the stator fin is defined as the mounting angle of the stator fin. If a plurality of stator fins are arranged in the hull so that the angle becomes 20 ° to 40 °, the flow of fluid to the propeller is favorably converted to the direction opposite to the propeller rotation direction by each stator fin to improve the propulsion efficiency. It becomes possible. As a result, this marine propulsion efficiency improving device can be easily constructed at low cost and is extremely suitable for relatively large vessels.

  In addition, among the plurality of stator fins, the stator fin disposed at least in the propeller ascending region where the propeller blade tip rises during forward rotation of the propeller is twisted so as to rectify the inflowing fluid with a torsion angle of 30 ° or less. May be. As a result, the angle of attack of each stator fin with respect to the inflowing fluid is made substantially constant in the span direction (between the root part and the fin blade tip), and a flow in the direction opposite to the rotation direction of the propeller is generated more favorably. Can be made larger. And among the plurality of stator fins, the stator fin disposed at least in the propeller ascending region where the propeller blade tip rises during forward rotation of the propeller, the fluid flowing in with a torsion angle smaller than the mounting angle of the stator fin. It may be twisted to rectify.

  Further, the plurality of stator fins are formed such that the length of the root portion is 10 to 20% of the diameter of the propeller and the length of the fin blade tip is 5 to 10% of the diameter of the propeller. May be. Thereby, the angle of attack of each stator fin can be increased and the lift-drag ratio can be improved.

  The plurality of stator fins may be formed such that an angle formed between the fin leading edge and the fin blade tip is 45 ° to 75 °. As a result, it is possible to improve the propulsion efficiency of the ship by suppressing the generation of vortices in the vicinity of the blade tip of the stator fin.

  The ship to which the marine vessel propulsion efficiency improving apparatus according to the present invention is applied is preferably applied to, for example, an enlarged ship having a square coefficient (Cb) of 0.75 or more.

The construction method of the marine propulsion efficiency improving device according to the present invention is as follows.
A method for constructing a marine vessel propulsion efficiency improving apparatus comprising a plurality of stator fins radially disposed so as to be located on the bow side of the propeller with respect to a hull of a ship including a propeller that generates thrust,
(A) forming the plurality of stator fins such that when attached to the hull, the length from the propeller axis to the fin blade tip is 70% or less of the radius of the propeller;
(B) An angle formed between a plane including the fin trailing edge of the stator fin and the propeller axis and a plane including the chord on the cross section of the root portion of the stator fin and the fin trailing edge of the stator fin. Fixing the plurality of stator fins to the hull so that the mounting angle is 20 ° to 40 ° when the mounting angle is set;
Is included.

  As in this method, a plurality of stator fins are formed such that the length from the propeller shaft center to the fin blade tip is 70% or less of the propeller radius when attached to the hull, and the fin trailing edge of the stator fin And the angle between the plane including the propeller axis and the plane including the chord and the fin trailing edge on the cross section at the root portion of the stator fin, the mounting angle is 20 ° to 40 °. If a plurality of stator fins are fixed to the hull so as to be at an angle, a marine vessel propulsion efficiency improving device suitable for a relatively large vessel can be easily constructed at low cost.

  Next, the best mode for carrying out the present invention will be described with reference to examples.

  FIG. 1 is a schematic configuration diagram showing a ship 10 including a marine vessel propulsion efficiency improving apparatus 20 according to an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of a main part of the ship 10. A ship 10 shown in these drawings is configured as a so-called enlargement ship such as an oil tank ship or a bulk carrier, and in the embodiment, a single body that generates thrust in the forward direction when rotated clockwise in FIG. A propeller 11, a rudder 12, a main machine (not shown) connected to the propeller 11, auxiliary equipment related thereto, and the like are provided. Further, the marine vessel propulsion efficiency improving apparatus 20 includes a plurality of stator fins P1, P2, P3, S1 that are radially welded and fixed to the bowing 15 (hull) of the vessel 10 so as to be positioned on the bow side of the propeller 11. Consists of S2. The stator fins P1 to P3 include a propeller shaft center when the propeller 11 is rotated forward when the propeller 11 rotates in the forward direction of the propeller 11, that is, when the propeller 11 rotates clockwise as viewed from the stern side. It is arranged in a region on the port side of the plane extending in the vertical direction. Hereinafter, the stator fins P1 to P3 arranged in the propeller ascending region are collectively referred to as “stator fins Pn”. Further, the stator fins S1 to S2 are arranged in a propeller descending region where the propeller blade tip descends when the propeller 11 rotates forward, that is, when the propeller 11 rotates clockwise as viewed from the stern side, the propeller shaft is centered. It is arranged in the region on the starboard side with respect to the plane extending in the vertical direction. Hereinafter, the stator fins S1 and S2 arranged in the propeller descending region are collectively referred to as “stator fin Sn”. In the embodiment, the stator fins Pn and Sn are dimensioned so that the length ds from the propeller shaft center to the fin blade tip (tip) is 70% or less of the propeller radius dp when attached to the boshing 15. It is formed as having. In determining the dimensions of the stator fins Pn and Sn, examination was made from both aspects of the propulsion efficiency improvement by the marine propulsion efficiency improvement device 20, the strength of the stator fins Pn and Sn itself, and the attachment strength to the bossing 15.

  First, assuming that there are an infinite number of wings of a propeller, the propeller can be regarded as one actuator disk. Therefore, it is assumed that the working disk is traveling in water that is infinitely spread at a constant speed VA while rotating at an angular speed Ω, and a cylindrical coordinate system having the origin at the center of the working disk is introduced, Let us consider the flow velocity and pressure on the streamline passing through the annular element of minute thickness dr at the position of radius r of the working disc. In this case, the velocity component in the x direction is circular with respect to three cross sections: the disk surface (x = 0), its heel or front (x = xf <0), and its heel or rear (x = xa> 0). The velocity components in the x direction at the cross sections x = 0, x = xf, and x = xa are assumed to be VA, VA + wa1, and Va + wa, respectively. Further, the speed component in the rotation direction of the working disk is discontinuous on the disk surface, and has a value 0 in front of the disk and a constant speed −wt (<0) in the rear. Furthermore, the velocity component in the radial direction of the working disk can be ignored as being small. Regarding these three cross sections, the law of conservation of mass, the law of conservation of momentum, the law of conservation of angular motion, and the law of conservation of energy are applicable, so that the force in the X direction acting on the annular element, that is, the thrust dT, and the action on the annular element. The moment, that is, the torque dQ to be expressed can be expressed by the following equations (1) and (2), respectively. Further, by using the equations (1) and (2), the thrust T and the torque Q acting on the operating disk, that is, the entire propeller, can be expressed as the following equations (3) and (4). However, in the formulas (1) and (2), Va = 2π · r · dr, a = wa / (2 · VA), and a ′ = wt / (2 · Ω · r). And the thrust and torque which act on the said propeller can be calculated | required by applying the measurement result of the flow behind a certain propeller with respect to the relationship of these Formula (1)-(4). FIG. 3 shows the result of deriving the torque acting on each propeller radial position based on the measurement result of the flow behind a certain propeller and the above formulas (1) to (4). In FIG. 3, the solid line indicates the torque when the speed component −wt in the rotation direction behind the propeller, that is, the torque component a ′ in the rotation direction in Equation (2) is considered, and the broken line indicates the rotation direction behind the working disk. The speed component -wt, that is, the torque when the speed component a 'in the rotational direction in the equation (2) is ignored is shown. The two-dot chain line is due to the difference between the solid line torque and the broken line torque, that is, the generation of the rotation component behind the propeller. Indicates the increase in torque. In the example of FIG. 3, the increase in torque due to the generation of the rotational component behind the propeller accounts for about 12.5% of the total torque (solid line). It is possible to improve the propulsion efficiency.

dT = 2 ・ ρ ・ dA0 ・ VA ²・ (1 + a) ・ a (1)
dQ = 2 ・ ρ ・ dA0 ・ (VA ³ / Ω) ・ (1 + a) ²・ a / (1 + a ') (2)
T = 2π · ∫dT / dA0 · r · dr (3)
Q = 2π · ∫dQ / dA0 · r · dr (4)

  Here, the marine vessel propulsion efficiency improvement device including a plurality of stator fins is designed to increase the thrust by the propeller by weakening the swirl flow behind the propeller by converting the flow of fluid to the propeller in the direction opposite to the rotation direction of the propeller. It is. Therefore, in order to recover as much of the rotational component behind the propeller as possible as described above, the length from the propeller shaft center to the fin blade tip is essentially the same as the propeller radius when the stator fin is attached to the boshing. It is preferable to do so. However, as can be seen from FIG. 3, in the region where the ratio r / R of the outer diameter of the propeller and the outer diameter of the stator fin and the outer diameter of the propeller when the hull is mounted is 0.8 or more, rotation components are generated. The increase in torque due to is very small. Therefore, if the recovery rate of the rotational component is allowed to deteriorate slightly, the span of each stator fin is reduced in order to abandon the recovery of the rotational component on the outer periphery of the propeller and ensure the strength and mounting strength of the stator fin itself. It is thought that it may be.

  FIG. 4 shows the calculation result of the bending stress for a predetermined stator fin, and FIG. 5 shows the specifications of the stator fin for which the bending stress was calculated. Here, the safety factor in the calculation of the bending stress illustrated is the value 2, the propeller blade number is the value 4, the propeller rotation speed is 113 rpm, and the propeller blade frequency is 452 cpm. As can be seen from the results shown in FIG. 4, if the span of the stator fin is about 1.5 m, there is no problem in terms of strength. If the span of the stator fin is set to about 1.5 m as described above, the dimensions of the stator fin from the propeller shaft can be reduced when mounting to the boshing, considering the dimensions of the boring of a large ship such as a general oil tank ship or bulk carrier. The length to the fin blade tip is approximately 70% or less of the propeller radius.

  Based on the examination results related to the improvement degree and strength of the propulsion efficiency, the marine propulsion efficiency improvement apparatus 20 according to the embodiment has a length ds from the propeller shaft center to the fin blade tip when attached to the bossing 15. The stator fins Pn and Sn are formed so as to have a span of 70% or less of the radius dp of the propeller 11, more preferably 35% to 70%. Furthermore, in the marine vessel propulsion efficiency improving apparatus 20 of the embodiment, in order to increase the angle of attack of the stator fins Pn and Sn and improve the lift-drag ratio, the length of the root portion of the stator fins Pn and Sn is set to the propeller. 11 to 10 to 20% of the diameter of the fin 11, and the length of the fin blade tip was set to 5 to 10% of the diameter of the propeller 11. If the stator fins Pn and Sn are fixed to the bossing 15 by welding, the upper limit of the inflow speed of seawater to the stator fins Pn and Sn is about 6 m / s. Stator fins Pn and Sn having a span of a degree are suitable for a ship having a propeller having a wake coefficient (1-Ws) of about 0.7 and a ship speed of about 16 to 17 kn and an outer diameter of about 10 m. Can also be applied.

  Next, the mounting angles of the above-described stator fins Pn and Sn will be described. In the following description, as shown in FIG. 2, an angle formed by a plane extending vertically upward including the propeller axis and a plane including the fin trailing edges of the stator fins Pn and Sn and the propeller axis is defined as the stator fin Pn. , Sn in the circumferential direction are referred to as φp1, φP2,..., ΦS1, φS2,... (Deg) (hereinafter, the mounting position is simply referred to as “φ” as appropriate). As shown in FIG. 2, the mounting position φ is positive on the port side of the ship 10 from the axis extending vertically upward, and positive on the starboard side of the ship 10 from the axis extending vertically upward. To do. Further, as shown in FIG. 6, a plane including the fin trailing edges of the stator fins Pn and Sn and the propeller axis, and a chord (nose−) on the cross section at the root portion (surface of the boshing 15) of the stator fins Pn and Sn. The angle formed between the tail line) and the plane including the fin trailing edge is referred to as the mounting angle ψ (deg) of the stator fins Pn and Sn. The mounting angle ψ is positive on the port side of the ship 10 when the hull is viewed from the port side, and the clockwise direction is positive with respect to the propeller axis, and on the starboard side of the ship 10, the propeller is viewed from the starboard side. Clockwise with respect to the axis is positive. Further, as shown in FIG. 6, the angle ψt formed between the mounting angle ψ of the stator fins Pn and Sn and the plane including the chord (nose-tail line) and the fin trailing edge at the fin blade tip of the stator fins Pn and Sn. This difference is called the twist angle γ (deg) of the stator fins Pn and Sn. Then, as shown in FIG. 7, a plane including the fin trailing edges and the propeller shafts of the stator fins Pn and Sn, and a chord on a cross section (nose-tail line) at an arbitrary radial position of the stator fins Pn and Sn. The angle obtained by subtracting the inflow angle β of the fluid (seawater) at the radial position from the angle ψr formed by the plane including the fin and the trailing edge of the fin is referred to as an angle of attack α. The inflow angle β can be calculated based on the axial flow velocity, the circumferential flow velocity, and the radial flow velocity at the radial position.

  In determining the mounting angles of the stator fins Pn and Sn, the present inventors have analyzed the flow around the propeller of the enlarged ship, and as a result, focused on the fluid inflow angle β with respect to the stator fins Pn and Sn. It was. That is, if the stator fins Pn and Sn are not twisted, the sum of the inflow angle β and the angle of attack α of the stator fins Pn and Sn becomes the mounting angle ψ of the stator fins Pn and Sn. Is an important factor that determines the angle of attack α of the stator fins Pn and Sn and the mounting angle ψ of the stator fins Pn and Sn that are closely related to the lift-drag ratio. Therefore, the present inventors have obtained the inflow angle β of the fluid by analysis on the surface of the bossing 15 (the root portion of the stator fins Pn and Sn) at each mounting position φ described above in a state where the stator fins Pn and Sn are not present. . FIG. 8 shows the analysis result of the relationship between the mounting position φ and the inflow angle β. This analysis was performed on two ships of Examples 1 and 2. The specifications of the ship of Example 1 were Cb = 0.85, L / B = 5.76, B / d = 2.85, γA. (Stern hypertrophy) = 0.66, and the specifications of the ship of Example 2 are Cb = 0.79, L / B = 5.95, B / d = 3.32, γA (stern hypertrophy) = 0.49. As shown in FIG. 8, in the ship of Example 1, the inflow angle β is a value in the range of approximately 0 ° to 30 °, and in the ship of Example 2 having a thin ship shape as compared with the ship of Example 1, the inflow angle It turned out that (beta) becomes a value within the range of about 0 degree-20 degrees.

  Here, based on general blade theory, the stator fin Pn disposed in the propeller ascending region (port side) where the propeller blade tip rises when the propeller 11 rotates forward is circulated with a higher lift-drag ratio. In order to further increase the angle, it is preferable to set the angle of attack α to about 10 °. On the other hand, as for the propeller descending region (starboard side) where the propeller blade tip descends when the propeller 11 rotates forward, the results of experiments and analysis by the present inventors show that the emphasis is on the lift-drag ratio based on the blade theory. Emphasizing wake recovery, the stator fin Sn converts the flow of fluid to the propeller 11 well in the direction opposite to the rotation direction of the propeller 11, and causes separation on the surface of the stator fin Sn to cause fluid flow around the stator fin Sn. It has been found that the angle of attack α should be relatively large so that the flow velocity can be reduced and thereby the wake energy can be recovered well. As a result of further experiments and analysis by the present inventors, in order to change the flow direction in the propeller descending region and cause separation on the surface of the stator fin Sn, the angle of attack α of the stator fin Sn is set to about 45. It has been found that practically good results can be obtained when the angle is in the range of 60 ° to 60 °, more preferably about 50 °. From such a viewpoint, the marine vessel propulsion efficiency improving apparatus 20 according to the present invention determines the mounting angle ψ of the stator fins Pn and Sn based on the inflow angle β obtained by the analysis and the above-mentioned preferred angle of attack α. The torsion angle γ is given to the stator fin Sn arranged at least in the propeller ascending region. That is, in the present invention, for the stator fin Pn in the propeller ascending region, the mounting angle ψ and the torsion angle so that the angle of attack α between the root portion and the fin blade tip is approximately constant, for example, approximately 10 ° on average. In particular, for the stator fin Sn in the propeller descending region where the value of the mounting position φ is large, the angle of attack α between the root portion and the fin blade tip is, for example, in the range of 45 ° to 60 °. The mounting angle ψ is set so as to be substantially constant at an inner value (more preferably 50 °). In order to set the angle of attack α to such a suitable value, the mounting angle ψ is set to a value within the range of 20 ° to 40 °, and the torsion angle γ is set to a value of 30 ° or less. It was. Further, from the analysis result of the flow around the propeller, in the present invention, in order to suppress the generation of vortices in the vicinity of the blade tips of the stator fins Pn and Sn and to improve the propulsion efficiency of the ship 10, the fin leading edge and the fin blade tip are further improved. The stator fins Pn and Sn are formed so that the angle θ (see FIG. 2) formed by

  Based on such design guidelines, the present inventors conducted analysis by CFD (Computational Fluid Dynamics) and a tank test using a model ship, and compared performance among a plurality of marine propulsion efficiency improvement devices. went. FIG. 9 shows specifications and performance comparison results of a plurality of marine propulsion efficiency improvement devices. In FIG. 9, Example 1 is a marine vessel propulsion efficiency improving apparatus that is premised on application to the ship of Example 1 above, and Example 2 is a marine vessel propulsion efficiency improving apparatus that is assumed to be applied to the ship of Example 2 above. is there. In addition, the marine vessel propulsion efficiency improving device based on the assumption that the example 1 is applied to a ship has three stator fins (P1 to P3 and S1) in each of a propeller ascending region (port side) and a propeller descending region (star side). To S3). Further, the marine vessel propulsion efficiency improving device that is assumed to be applied to the ship of Example 2 includes two stator fins (P2 and P3) in the propeller ascending region (port side) and 3 in the propeller descending region (star side). This includes a single stator fin (S1 to S3). Further, the performance evaluation index εEHP shown in FIG. 9 is an effective horsepower (in the ship (large ship)) of Examples 1 and 2 equipped with the marine vessel propulsion efficiency improvement device under a predetermined condition (constant ship speed, constant fluid number, etc.). EHP) is a value obtained by dividing the calculated value of effective horsepower when the ship propulsion efficiency improving device is omitted from the ship. Further, the performance evaluation index εBHP omits the calculated value of the braking propulsion efficiency (BHP) in the ships of Example 1 and Example 2 equipped with the marine vessel propulsion efficiency improving device under the predetermined conditions from the vessel. It is the value divided by the calculated value of braking horsepower in the case. As can be seen from the performance comparison results in FIG. 9, in the ships of Examples 1 and 2 equipped with the marine vessel propulsion efficiency improvement device according to the present invention, the performance evaluation index εBHP is below the value 1, and from this point, according to the present invention. It can be said that the marine vessel propulsion efficiency improving device is practically effective in improving the vessel propulsion efficiency. Further, from the result of FIG. 9, the mounting angle ψ of the stator fins Pn and Sn is set to a value within the range of 20 ° to 40 °, and the angle of attack α of the stator fins Pn and Sn with respect to the flowing fluid is set in the span direction. It turns out that it is practically very effective to twist the stator fin Pn arranged at least in the propeller ascending region so as to rectify the inflowing fluid with a torsion angle γ of 30 ° or less so as to be substantially constant. Furthermore, as in Example 1 of FIG. 9, depending on the ship, if a torsion angle γ smaller than the mounting angle ψ is given to the stator fin Pn arranged at least in the propeller ascending region, a practically good result can be obtained. It was also found out.

  As described above, in the above-described marine propulsion efficiency improving device 20, a plurality of lengths from the propeller shaft center to the fin blade tip when attached to the bossing 15 are 70% or less of the radius of the propeller 11. Stator fins Pn and Sn are formed. As a result, the strength of the stator fins Pn and Sn can be sufficiently secured, and the mounting strength of the stator fins Pn and Sn to the boshing 15 can be sufficiently secured even if the stator fins Pn and Sn are fixed to the boshing 15 by welding. can do. In addition, the angle formed by the plane including the fin trailing edge and the propeller axis of the stator fins Pn and Sn and the plane including the chord and the fin trailing edge on the cross section at the root portion of the stator fin Pn and Sn If a plurality of stator fins Pn and Sn are disposed on the boshing 15 (hull) so that the mounting angle ψ is 20 ° to 40 °, the lift-drag ratio is increased in the propeller ascending region. The angle of attack α of the stator fin Pn is set so as to increase the circulation, and in the propeller descending region, the flow of the fluid with respect to the propeller 11 is favorably converted to the direction opposite to the rotation direction of the propeller 11 by the stator fin Sn. In order to reduce the flow velocity of the fluid around the stator fin Sn by causing separation on the surface of the fin Sn, the stator fin Sn The angle of attack α can be set. Therefore, in the marine vessel propulsion efficiency improving device 20, it is possible to improve the propulsion efficiency by converting the flow of the fluid to the propeller 11 favorably in the direction opposite to the rotation direction of the propeller 11 by the stator fins Pn and Sn. As a result, the marine vessel propulsion efficiency improving device 20 can be easily constructed at low cost and is extremely suitable for a relatively large vessel.

  Furthermore, if a torsion angle γ of 30 ° or less is given to the stator fin Pn arranged at least in the propeller ascending region, the angle of attack α of the stator fin Pn with respect to the flowing fluid is made substantially constant in the span direction. It is possible to generate a flow in the direction opposite to the rotation direction better and to increase the lift-drag ratio. Depending on the ship, if the twist angle γ of the stator fin Pn disposed at least in the propeller ascending region is smaller than the attachment angle ψ, a practically good result can be obtained. Of course, it goes without saying that the torsion angle γ may be applied to all the stator fins Pn and Sn. Further, if the length of the root portion of the stator fins Pn and Sn is 10 to 20% of the diameter of the propeller 11 and the length of the fin blade tip is 5 to 10% of the diameter of the propeller 11, the stator fin Pn , Sn can be increased in angle of attack and the lift-drag ratio can be improved. Furthermore, if the stator fins Pn and Sn are formed so that the angle between the fin leading edge and the fin blade tip is 45 ° to 75 °, the stator fin Pn can be used without using bladelets (blade tip blades) or the like. , It is possible to further improve the propulsion efficiency of the ship 10 by suppressing the generation of vortices near the tip of Sn.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. Needless to say.

  The present invention can be used in the ship manufacturing industry and the like.

It is a schematic block diagram which shows the ship 10 provided with the ship propulsion efficiency improvement apparatus 20 which concerns on one Example of this invention. 1 is an enlarged perspective view of a main part of a ship 10. It is explanatory drawing which shows the result of having derived the torque which acts on each radial direction position of the said propeller based on the measurement result etc. of the flow in the back of a certain propeller. It is explanatory drawing which shows the calculation result of the bending stress about a stator fin. It is explanatory drawing which shows the item of the stator fin which performed the calculation of the bending stress relevant to FIG. 1 is an enlarged perspective view of a main part of a ship 10. 1 is an enlarged perspective view of a main part of a ship 10. It is explanatory drawing which shows the analysis result about the relationship between attachment position (phi) and inflow angle (beta). It is explanatory drawing which shows the item of several marine propulsion efficiency improvement apparatuses, and a performance comparison result.

Explanation of symbols

  10 ship, 11 propeller, 12 rudder, 15 boshing, 20 ship propulsion efficiency improvement device, P1, P2, P3, S1, S2, S3 stator fin.

Claims (7)

A marine vessel propulsion efficiency improvement device comprising a plurality of stator fins radially disposed so as to be located on the bow side of the propeller with respect to a hull of a ship including a propeller that generates thrust,
The plurality of stator fins are formed such that when attached to the hull, the length from the propeller axis to the fin wing tip is 35% to 70% of the radius of the propeller. When the angle formed between the plane including the fin trailing edge and the propeller axis and the plane including the chord on the cross section of the root portion of the stator fin and the fin trailing edge is defined as the mounting angle of the stator fin, A marine vessel propulsion efficiency improving device disposed in the hull so that the mounting angles of all the stator fins are in a range of 20 ° to 40 °. In the marine vessel propulsion efficiency improvement device according to claim 1,
Among the plurality of stator fins, at least a stator fin disposed in a propeller ascending region where a propeller blade tip rises during forward rotation of the propeller is twisted so as to rectify the flowing fluid with a torsion angle of 30 ° or less. Marine propulsion efficiency improvement device. In the marine vessel propulsion efficiency improvement device according to claim 1 or 2,
Among the plurality of stator fins, at least a stator fin disposed in a propeller ascending region where a propeller blade tip rises during forward rotation of the propeller rectifies fluid flowing in with a twist angle smaller than the mounting angle of the stator fin. A marine propulsion efficiency improvement device that is twisted like so. In the marine vessel propulsion efficiency improvement device according to any one of claims 1 to 3,
The plurality of stator fins are formed so that the length of the root portion is 10 to 20% of the diameter of the propeller and the length of the fin blade tip is 5 to 10% of the diameter of the propeller. Propulsion efficiency improvement device. In the marine vessel propulsion efficiency improvement device according to any one of claims 1 to 4,
The plurality of stator fins are marine propulsion efficiency improving devices formed so that an angle formed between a fin leading edge and a fin blade tip is 45 ° to 75 °.   The marine vessel propulsion efficiency improving apparatus according to any one of claims 1 to 5, wherein the marine vessel is an enlarged vessel. A method for constructing a marine vessel propulsion efficiency improving apparatus comprising a plurality of stator fins radially disposed so as to be located on the bow side of the propeller with respect to a hull of a ship including a propeller that generates thrust,
(A) forming the plurality of stator fins such that when attached to the hull, the length from the propeller axis to the fin blade tip is 35% to 70% of the radius of the propeller;
(B) An angle formed between a plane including the fin trailing edge of the stator fin and the propeller axis and a plane including the chord on the cross section of the root portion of the stator fin and the fin trailing edge of the stator fin. Fixing the plurality of stator fins to the hull so that the mounting angles of all the stator fins are in the range of 20 ° to 40 ° when set as the mounting angles;
A method for constructing a marine propulsion efficiency improving device.

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