TW523481B - Mechanism and method for reducing vessel vibration and noises - Google Patents

Abstract

This invention relates to a mechanism and method for reducing vessel vibration and noises, mainly related to providing a set of hydrofoil at a symmetrical location of opposing sides next to the stern sampan of a water drainage vessel, subject the hydrofoils to divert a swirl and to effectively induce the swirl, and providing a diversion board at the front side of the stern propeller of the water drainage vessel at a height close to symmetrical locations of an upper edge of the propeller so as to effectively induce the location which the swirl enters the propeller. The induced swirl also causes mixing of the flow field so as to effectively improve the distribution of the stern trails, and to reduce the void swirl thereby significantly reducing the stern vibration and noises.

Description

523481 V. Description of invention (υ Prior technology: In recent years, the demand for container ships in the world's shipping market has continued to increase, resulting in the rapid development of container ships. Generally speaking, container ships generally have higher ship speeds than traditional ships. With large horsepower, however, because many container wheels place part of the container design behind the bow, so that the bow part has a wider stern area. At this time, if the reason When the position is too close to the bow, the bow shape of the bow will be reduced sharply. When the water flow passes through the bow with this kind of line, it will easily cause uneven track flow distribution. Refer to Figure 1, it should be A schematic diagram of the nominal trace flow of the propeller surface of a container wheel, in which the right half is a dimensionless axial velocity contour map, and the nose result is 'the left half is an experimental result.' The main reason for the distribution is that a fairly obvious low-speed area is generated near its centerline. When the propellers are moved in this unevenly distributed track flow, the inflows of the sections of the propeller blades The angle of attack is too large. As shown in Figure 2, it is easy to produce a cavitation vortex V at the wing end of the propeller 4, and the resulting vibration and noise may be transmitted to the hull by the vortex touching the rudder surface 6 In addition, due to the obvious change in the inflow angle of attack of the propeller blade cross section, the propeller load has also changed significantly, both of which have caused problems such as vibration and noise on the bow. These problems are generally caused by the vibration and The noise problem is not the same. Refer to Figure 3, which is the vibration amplitude measured at the tail end of the main stern plate of this type of container wheel. The main vibration amplitude occurs under the high-frequency operation state of the propeller. It is difficult to effectively improve the condition through structural damping. Generally speaking, the vibration and noise problems caused by fluids must be analyzed from the perspective of fluid mechanics and borrowed from

Page 4 523481 V. Description of the invention (2) By improving the distribution of the track flow, it is expected to effectively reduce the problems of ship vibration and noise caused by the fluid. According to the current technology used to improve the distribution of ship track flow, the purpose is to reduce ship resistance or enhance fluid energy recovery to improve the efficiency of ship propulsion. For example, the technology disclosed in US Patent No. 4, 6 3 1, 0 3 6 is shown in Figure 4. It is mainly on the left and right corresponding sides of the front of the bow 3 of the propeller 4, and each row is designed to be vertical. Horizontal rectification guide plate 50 arranged in the direction to adjust the inflow direction and velocity of the propeller to increase the efficiency of the propeller; the technology disclosed in Japanese Patent Laid-Open Publication No. 5 9-5 0 8 8 9 patent, see FIG. 5 As shown in the figure, the curved slender wings 51 are installed on the two opposite sides of the bow 3 to reduce or eliminate the eddy vortex; the technology disclosed in Japanese Patent Publication No. 2 6 2 3 8 9 5 is referred to as No. 6 As shown in the figure, a horizontally extending wing plate 5 2 is installed on each of the two corresponding sides in front of the propeller shaft 4 1 of the bow 3 to reduce the eddy current and increase the pressure recovery of the bow to reduce ship resistance. Japan The technology disclosed in Japanese Patent Laid-Open No. Sho 6 3-1 9 9 8 9 7 is shown in Fig. 7, which is provided with a pair of horizontal wings 5 3 in front of the bow 3 propeller shaft 4 1 and its vertical direction is Near the upper edge of the diameter of the propeller 4, the turbulence generated by the rectified eddy current is used to improve the propulsion efficiency; The technology disclosed in the patent No. 7-3 4 7 9 is shown in Fig. 8. It is equipped with a pair of horizontal wings 5 4 with end plates in front of the stern 3 propeller shaft 4 1 to improve the distribution of the sloping stream. To improve the propulsion efficiency; the technology disclosed in Japanese Patent Application Laid-Open No. Hei 9-1 3 6 6 9 3, as shown in Fig. 9, is obtained by installing curved wings 5 5 on each side of the bow 3 Bismuth vortex energy; the technology disclosed in Japanese Patent Laid-Open Publication No. 9-1 9 3 8 9 2 is shown in Fig. 10, and a horizontal wing 5 6 is installed on each side of the bow.

523481 V. Description of the invention (3) To improve the stern propeller flow field and effectively improve the propulsion efficiency of the ship. It can be known from the foregoing that these previous technologies are all applied to the bow of the ship. The method is to use a diversion or spoiler to reduce resistance, achieve the purpose of increasing its propulsion efficiency, or improve its maneuverability. For the use of similar guidance Flow or spoiler mechanisms are relatively rare to improve bow vibration and noise problems.

For example, the technology disclosed in the US Patent No. 4,0 6,9,8,8, as shown in Figure 11, is located on the left and right sides of the propeller 4 of the bow 3, each using a duct to suck the full flow of the boat The seawater in the area is discharged to the low-speed area in front of the propeller by using the suction generated by the propeller to improve the efficiency of the propeller and the vibration problem caused by the propeller; American invention No. 4, 1 3 5, 4 6 9 The technology disclosed by the patent, as shown in Fig. 12, is on the left and right sides of the ship's stern in front of the bow 3, with a row of vertically arranged openings 5 and 8 respectively. At the place where the propeller 4 flows, the buffer effect of the gas is used to improve the vibration and noise problems caused by the propeller.

Generally speaking, the underwater hull of the stern of a displacement ship is spherical in shape, which is used to reduce the resistance to wave-making. Most of the stern is a parallel middle body to provide cargo volume. Due to the viscosity of the fluid, It will cause it to flow away from the bottom of the bow, form a symmetric vortex system, and flow through the bow. Therefore, it is usually called a bismuth vortex. This vortex develops along the length of the ship and then flows into the propeller. surface. Because the full flow has high fluid energy, it will have a disturbance effect on the inflow of the propellers. Most of the previous technologies focus on this. Different diversion or rectification devices are used to reduce or eliminate thorium and eddy currents, thereby reducing ship resistance. For the purpose of recovering fluid energy or improving propulsion efficiency.

Page 6 523481 V. Description of the invention (4) The problem is not known, so the outline of the invention cannot be effectively solved: In view of the sharp reduction of the linear shape of the traditional container ship, the flow of water through its bow can easily cause inconvenience. The uniform trajectory flow is distributed, and a fairly obvious low-speed region is generated near the centerline. When the propeller is operated in the uneven trajectory flow, the inflow angle of attack of the sections of the propeller blade changes too much. A strong cavitation vortex at the blade end of the propeller is generated, and the vibration and noise derived from it are transmitted to the hull by the vortex touching the rudder surface, which causes the problem of vibration and noise on the bow. The inventor has developed A mechanism and method for reducing vibration and noise of a ship. A group of hydrofoils can be installed on a displacement ship near the stern of the ship, so that the group of hydrofoils can be used to divert bismuth vortices. It can generate an effective induced eddy current. The displacement ship is near the front of its propeller and its height is approximately the symmetrical position of the upper edge of the propeller. With the deflector set by the group of hydrofoils, Control the position where the induced vortex enters the propeller surface, and use the induced vortex to mix the flow field to effectively improve the uniformity of the distribution of the trail flow, reduce the cavitation vortex at the propeller wing end, and greatly reduce the bow vibration and Noise problem. Now, in order to express the technical means and operation process of the present invention more clearly, a preferred embodiment will be briefly described with reference to the drawings, as follows: The present invention is directed to a displacement vessel 1, see FIG. 13 In the case of the sharp reduction of the linear shape of the ship's bow 3, when the water flow passes through its bow 3, it is easy to cause an uneven track flow distribution, and near its center line, a fairly obvious low-speed area is generated, causing snails Paddles move in this uneven track

Page 7 523481 5. In the description of the invention (5), the inflow angle of attack of the cross sections of the blades of the propeller 4 is likely to change too much, resulting in a strong cavitation vortex at the blade end of the propeller 4 and thus the resulting vibration and noise. When the eddy current touches the rudder surface 6 and is transmitted to the hull, it causes vibration and noise problems on the bow, and these problems are mainly caused by the flow of water flowing through the bow with a lower full flow trajectory. This phenomenon prevents the inflow of the propeller from getting enough fluid mixing effect, resulting in a fairly uneven distribution of the trace flow. Therefore, to effectively solve these problems, it is necessary to greatly improve the uniformity of the distribution of the trace flow in order to To achieve the purpose of effectively reducing bow vibration and noise. The present invention mainly utilizes the characteristic of higher energy of the water flow in the eddy vortex, and by introducing part of the eddy vortex into the uneven area of the eddy current, the strong rotation characteristic of the bismuth vortex can drive the mixing effect of the fluid to effectively improve 艉The uniformity of the trace. In a preferred embodiment of the present invention, as shown in FIG. 13, it is attached to a drainage vessel 1 at a symmetrical position below the waterline 2 near its bow 3 艉 and at the vortex, respectively. A group of hydrofoil A uses this group of hydrofoil A to divert the eddy current B while generating an effective induced vortex C. The hydrofoil A must have a sufficient angle of attack with the direction of the nearby water flow, so that the induced vortex C generated has sufficient initial strength and can gradually grow along the length of the ship, so that high-speed fluids farther from the hull are It is brought into a low-speed area close to the hull of the ship, so the design position of the hydrofoil A must allow the induced full flow C to have sufficient development space, and the induced vortex C can be used to mix the flow field and effectively improve the propeller. Uniformity of surface flow. In this embodiment, the hydrofoil A is arranged symmetrically below the waterline 2 near the stern of the ship's bow 3, and its installation position is about 15% to 25% of the ship's longitudinal distance. (Indicated by the symbol LP), which is perpendicular to the bottom of the ship

523481 V. Description of the invention (6) Momentary distance is about 20% ~ 30% draught (represented by symbol T), and the angle between the hydrofoil A and waterline 2 (represented by symbol α) is about 30 ° ~ 60 °, the trailing edge of the hydrofoil A is perpendicular to the bottom of the ship, which is higher than its leading edge. The hydrofoil A is shaped and has the following characteristics: (1) The chord length of the hydrofoil A is approximately 0 · 5% ~ 1.5% of the ship's length; (2) The span length of the hydrofoil A can be changed along the chord length of the hydrofoil, and it can be increased along the chord length of the hydrofoil. The maximum wingspan is about the length of the hydrofoil length. 50% ~ 100%; (3) The cross-sectional shape of the hydrofoil A along the chord length direction is that its width increases from the outer end to the root, and the maximum thickness at the root does not exceed the wingspan at that location. 30% of the length. In this embodiment of the present invention, the drainage vessel 1 is located at the left and right symmetrical positions of the propeller 4 under the stern 3 and under the water 2 near the upper edge of the propeller. Plate D, the deflector D can be matched with the group of hydrofoil A to control the direction of the induced vortex C generated by the hydrofoil A so that it can correctly enter the proper position of the propeller surface and avoid the induced vortex C The position of entering the propeller surface is too high or too low to bring the fluid in the low velocity area out of the propeller surface, so as to effectively improve the uniformity of the flow on the propeller surface. In the embodiment, the design position of the deflector D is basically parallel to the waterline, and its shape has the following characteristics: (1) the length of the deflector D is about 2% to 8% of the ship's length; (2) The maximum width of the deflector D is about 5% to 15% of the length of the deflector. The width of the deflector D can vary along its length. The thickness of the deflector D is generally from the outer end.

523481 V. Description of the invention (7) The root is increased, and the maximum thickness of the root is based on the principle that the length of the deflector does not exceed 10%. Utilizing the design of the present invention, the hydrofoil A installed on the displacement vessel can effectively divert the eddy current B and generate an effective induced vortex C at the same time, bringing high-speed fluid farther from the hull into the hull near the hull. In the low-speed area, and with the deflector D, the induced eddy current C is properly guided into the proper position of the propeller surface, and the uniformity of the flow on the propeller surface is effectively improved, as shown in the nominal trace of the propeller surface in FIG. 14 As shown in the flow diagram, the inflow angle of attack of the cross sections of its propeller blades is changed, which is gentler than the traditional one without the hydrofoil A of the present invention. Refer to FIG. 15, where the left is the traditional Dimensionless axial speed distribution of the propeller surface on the bare hull of Hydrofoil A along different radii in the circumferential direction, and the figure on the right is the result of installing the hydrofoil A, and the axial velocity changes along the circumferential direction. Obviously becomes more moderate, which can not only reduce the variability of the propeller load, but also reduce the intensity of the propeller wing tip (cavitation) leakage. This can be actualized by the propeller surface in the bow structure shown in Figure 16 Experimental photos of operation to confirm that the displacement ship Stern vibration and noise problem can also be illustrated by FIG. 7 of the first type is mounted on the drain according to the present invention the trailing end of the ship's main vibration plate Yue measured amplitude data of FIG. 5 has significantly improved pay-known to persons. The above is only one of the preferred embodiments of the present invention. However, the scope of the rights claimed by the present invention is not limited to this. According to those skilled in the art, the technical content disclosed by the present invention can be easily implemented. All equivalent changes considered shall belong to the protection scope of the present invention.

523481 Simple illustration of the diagram Simple illustration of the diagram: Figure 1 shows the schematic trace of the nominal flow of the propeller surface of a traditional container wheel 'Figure 2 shows the propeller surface of a traditional container wheel, due to the cross sections of the propeller blades The experimental photo of the strong propeller wing end (cavitation) flow caused by the excessive change of the inflow angle of attack; Figure 3 shows the vibration amplitude data measured at the tail end of the main stern plate of a conventional container wheel. Shown is the intention of the stern structure disclosed in US Patent No. 4, 6 3 1, 0 3 6; Figure 5 shows the ship disclosed in Japanese Patent Application Laid-Open No. Sho 5 9-5 0 8 9艉 Structure diagram j Figure 6 shows the structure of the ship stern disclosed in Japanese Patent Publication No. 2 6 2 3 8 9 5; Figure 7 shows the Japanese Patent Laid-Open Publication Sho 6 3-1 9 9 8 9 The schematic diagram of the stern structure disclosed in the 7th patent, shown in Figure 8 is the intention of the stern structure disclosed in the Japanese Patent Gazette No. 7- -3 4 7 9 6 The figure shows the structure of the stern disclosed in Japanese Patent Laid-Open Publication No. 9-1 3 6 6 9 3; Figure 10 shows the Japanese Patent Laid-Open Publication No. 9-1 9 3 8 9 2 Schematic diagram of the stern structure disclosed; Figure 11 shows the schematic diagram of the stern structure disclosed in US Patent No. 4,06.9,7.88;

Page 11 523481 Brief description of the drawings Figure 12 shows the structure of the stern according to the invention patent No. 4, 1 3 5, 4 6 9; Figure 13 shows the structure of the stern of the present invention Schematic diagram: Figure 14 shows the nominal flow of the propeller surface in the bow structure of the present invention, and Figure 15 shows the upper edge of the propeller surface with different radii in the present invention and the traditional bow structure. Schematic diagram of circumferential dimensionless axial speed distribution; Figure 16 shows experimental photos of actual movement of the propeller surface in the bow structure of the present invention; Figure 17 shows the main deck aft of the container wheel of the present invention. Measured by

Vibration amplitude data graph. Explanation of drawing number • Discharge type ship 1 boat 3 propeller 4 rudder surface 6 hydrofoil A boat must vortex B induce / 1 ¾ flow C deflector D

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Claims (1)

523481 年 (year six, patent application scope, patent application scope: 1. A method for reducing ship vibration and noise, mainly on a displacement ship close to the symmetrical position of the bow of the ship, a group of hydrofoil devices are installed, The installation position of the hydrofoil is 15% ~ 25% of the ship's length from the vertical mark of the bow; and the vertical distance from the bottom of the ship is 20% ~ 30% of the draught; and the angle with the waterline At an angle of 30 ° ~ 60 °, the hydrofoil device induces an induced vortex with sufficient initial strength. The induced vortex can gradually grow along the length of the ship, so that high-speed fluids farther from the hull are brought into it. To the low-velocity area near the hull of the ship, the induced eddy current can have a mixed effect of different flow fields under sufficient development space, and a group of left and right symmetrical positions close to the upper edge of its propeller under the bow's water are installed separately. Diversion device, the length of the diversion device is 2% ~ 8% of the ship's length, and its maximum width is 5% ~ 15% of the length of the diversion device. The width of the diversion device can be changed along its length. The diversion device controls the induced eddy current. direction Make it able to enter the proper position of the propeller surface correctly, bring the fluid in the low velocity area out of the propeller surface, and improve the uniformity of the trail flow on the propeller surface. 2. A mechanism for reducing ship vibration and noise, including (a ) The hydrofoil device in the symmetrical position of the bow of the stern, the installation position of the hydrofoil is 15% ~ 25% of the length of the ship from the vertical mark of the bow; and the distance of 20% ~ from the bottom of the ship 30% draught; and the angle between the waterline and the waterline is 30 ° ~ 60 °; (b) a guide device for the left and right symmetrical position of the upper edge of the propeller, guide device Page 13 523481 VI. Scope of patent application The installation length is 2% ~ 8% of the ship's length, and its maximum width is 5% ~ 15% of the length of the diversion device. The width of the diversion device can be changed along its length. 3. The mechanism described in item 2 of the scope of patent application, wherein the vertical distance between the trailing edge of the hydrofoil and the bottom of the ship is higher than its leading edge. 4. The mechanism described in item 2 of the scope of patent application, wherein the chord length of the hydrofoil is 0.5% ~: L 5% of the length of the ship, and its wingspan length can be changed along the direction of the chord length of the hydrofoil. It will move along the chord length of the hydrofoil and the maximum wingspan will be 50% ~ 100% of the hydrofoil length. 5. The mechanism as described in item 2 of the scope of patent application, wherein the width of the cross section of the hydrofoil along the chord length direction increases from the outer end to the root, and the maximum thickness at the root is not more than 30 of the wingspan length at that place. %. 6. The mechanism described in item 2 of the scope of patent application, wherein the design position of the diversion device is parallel to the waterline. 7. The mechanism described in item 2 of the scope of patent application, wherein the thickness of the deflector increases from the outer end to the root, and the maximum thickness of the root does not exceed 10% of the length of the deflector. Page 14