阅读说明：本技术 一种船用减阻膜 (Drag reduction film for ship ) 是由 胡海豹 刘苏阳 石颖超 连薇 李和仁 陆天洋 于 2021-07-29 设计创作，主要内容包括：本发明涉及一种船用减阻膜,包括微孔、沟槽和背胶等。船体内部产生气泡后,通过船底的微孔沿着膜上沟槽向后运动,形成一层气膜层,以限制航行器表面边界层底部液体的横向运动,改善其近壁面流场的特性,有效降低壁面的摩擦阻力,从而获得较高的速度,同时也减少了能源消耗,充分发挥了其在环境保护方面“节能减排”的优势。此外,若有对应条件,也可通过“润湿阶跃效应”控制产气孔道的个数及分区,使其一部分产气而另一部分不产气,以期利用若干沟槽的集合束缚气膜,延长气膜的存在时间。(The invention relates to a marine drag reduction film which comprises micropores, grooves, gum and the like. After bubbles are generated in the ship body, the air bubbles move backwards along the grooves on the film through the micropores on the ship bottom to form an air film layer, so that the transverse movement of liquid at the bottom of the boundary layer on the surface of the aircraft is limited, the characteristic of a flow field close to the wall surface of the aircraft is improved, the frictional resistance of the wall surface is effectively reduced, the higher speed is obtained, the energy consumption is reduced, and the advantages of energy conservation and emission reduction in the aspect of environmental protection are fully exerted. In addition, if corresponding conditions exist, the number and the subareas of the gas generating pore channels can be controlled through the wetting step effect, so that part of the gas generating pore channels generate gas and the other part of the gas generating pore channels do not generate gas, the gas film is bound by the set of a plurality of grooves, and the existence time of the gas film is prolonged.)

1. A marine drag reduction film is characterized in that: the bottom of the ship body is made of polytetrafluoroethylene material, one side of the ship body is provided with a back glue which is fixed with the bottom of the ship body, and the other side of the ship body is provided with a plurality of grooves and micropores; the plurality of grooves are parallel to the advancing direction of the ship body, and the cross section of each groove is of a T-shaped structure; the bottoms of the grooves are acute angles, a platform is arranged between the two grooves, and micropores are arranged on the platform; the shape of the combined micro-hole on each platform is matched with the shape of the front end of the bottom of the ship body, and each micro-hole is communicated with the through hole at the bottom of the ship; after bubbles are generated inside the ship body, the micro-holes at the bottom of the ship move backwards along the grooves on the membrane to form an air membrane layer so as to limit the transverse movement of liquid at the bottom of a boundary layer on the surface of the aircraft, improve the characteristic of a flow field close to the wall surface of the aircraft and effectively reduce the frictional resistance of the wall surface.

2. The marine drag reduction film of claim 1, wherein: the polytetrafluoroethylene material is prepared by etching a plurality of grooves, polytetrafluoroethylene resin is pre-pressed into a film shape, and the microporous film with the groove structure is formed by etching after sintering and molding.

Technical Field

The invention belongs to the technical field of ship drag reduction, and relates to a marine drag reduction film.

Background

Speed is an important indicator for measuring the performance of ships and underwater vehicles. Under the same input power, the speed and the resistance thereof are approximately in a 0.5 power relationship. The resistance borne by the ship and the underwater vehicle respectively consists of three parts, namely frictional resistance, differential pressure resistance and wave-making resistance, wherein the friction resistance has the highest proportion, so that the reduction of the frictional resistance is a main method for increasing the speed and reducing the consumption. At present, the mainstream drag reduction methods include groove drag reduction, flexible wall drag reduction, air film drag reduction and the like, wherein the air film drag reduction is also widely applied in the industry. Based on the situation, the ship resistance reducing film is designed by the team of I to produce better effect in the aspect of resistance reduction. Patent CN101269695A relates to an air film drag reduction structure for inputting air to the bottom of a ship or forming an air film by means of the action of navigational speed and water flow, has great dependence on external conditions, can not ensure the continuous formation of the air film, and has certain limitation. Patent CN206555624U is a pipeline with a micro-groove drag reduction structure, wherein a plurality of protrusions are arranged on the inner wall of the pipeline, the protrusions are regular triangles and are in an annular array, and form V-shaped grooves. Although the structure is simple, the practicability is strong, the flow field of fluid on the contact surface is changed by utilizing the structure of the device, the thickness of a viscous bottom layer is increased, and the surface turbulent kinetic energy and the velocity gradient are reduced, so that the drag reduction is realized, but the device only researches the flow in a pipeline and does not relate to the movement (external flow) of a ship body. In addition, patent CN110484151A relates to a micro-groove drag reduction flexible film and a preparation method thereof, wherein one side of the micro-groove film is provided with a triangular groove structure unit, and the other side is provided with an adhesive layer, which is convenient for being quickly adhered to the surface of an aircraft. After the micro-groove film is covered on the surface of the aircraft, the air on the surface of the aircraft can be limited to move in the spreading direction when the aircraft flies at a high speed, and the frictional resistance of the wall surface is effectively reduced. The design utilizes the groove drag reduction, but is more suitable for aircrafts moving in the air, and the specific application of the underwater aircrafts is still lack of research.

Disclosure of Invention

Technical problem to be solved

In order to avoid the defects of the prior art, the invention provides a marine resistance reducing film, which solves the problems that an air film cannot exist continuously, other related cases have smaller application range and the like. The main material is Polytetrafluoroethylene (PTFE), which has certain hydrophobicity and also has the function of antifouling.

Technical scheme

A marine drag reduction film is characterized in that: the bottom of the ship body is made of polytetrafluoroethylene material, one side of the ship body is provided with a back glue which is fixed with the bottom of the ship body, and the other side of the ship body is provided with a plurality of grooves and micropores; the plurality of grooves are parallel to the advancing direction of the ship body, and the cross section of each groove is of a T-shaped structure; the bottoms of the grooves are acute angles, a platform is arranged between the two grooves, and micropores are arranged on the platform; the shape of the combined micro-hole on each platform is matched with the shape of the front end of the bottom of the ship body, and each micro-hole is communicated with the through hole at the bottom of the ship; after bubbles are generated in the ship body, the micro-pores at the bottom of the ship move backwards along the grooves on the membrane to form an air membrane layer so as to limit the transverse movement of liquid at the bottom of a boundary layer on the surface of the aircraft, improve the characteristic of a flow field near the wall surface of the aircraft, effectively reduce the frictional resistance of the wall surface,

the polytetrafluoroethylene material is prepared by etching a plurality of grooves, polytetrafluoroethylene resin is pre-pressed into a film shape, and the microporous film with the groove structure is formed by etching after sintering and molding.

Advantageous effects

The marine resistance reducing film provided by the invention comprises micropores, grooves, gum and the like. After bubbles are generated in the ship body, the air bubbles move backwards along the grooves on the film through the micropores on the ship bottom to form an air film layer, so that the transverse movement of liquid at the bottom of the boundary layer on the surface of the aircraft is limited, the characteristic of a flow field close to the wall surface of the aircraft is improved, the frictional resistance of the wall surface is effectively reduced, the higher speed is obtained, the energy consumption is reduced, and the advantages of energy conservation and emission reduction in the aspect of environmental protection are fully exerted. In addition, if corresponding conditions exist, the number and the subareas of the gas generating pore channels can be controlled through the wetting step effect, so that part of the gas generating pore channels generate gas and the other part of the gas generating pore channels do not generate gas, the gas film is bound by the set of a plurality of grooves, and the existence time of the gas film is prolonged.

The invention utilizes the air film drag reduction method and the groove drag reduction method to reduce drag. In addition, the device occupies a small area, so that the device is suitable for a high-speed small ship with relatively short voyage and high voyage speed.

The invention applies the air film resistance reducing method and the groove resistance reducing method to the ship resistance reducing device simultaneously to generate gas and form a stable air film, thereby maintaining the resistance reducing effect for a long time. The device adopts a groove structure on the outer surface of the film, can realize the function of stabilizing the gas film, the gas enters the groove through the micropores at the bottom of the ship, and the stable gas film is formed at the bottom of the ship through the hydrophobic effect of the polytetrafluoroethylene surface microstructure and the constraint effect of the groove, thereby finally realizing the aim of effectively reducing the resistance of the ship.

Meanwhile, the invention has a certain antifouling effect through hydrophobic property, and the characteristics of simple structure, easy realization, low manufacturing cost, environmental protection and energy saving also enable the invention to have a certain engineering application value in the field of ship drag reduction.

Drawings

FIG. 1 is a schematic longitudinal cross-sectional view of a marine drag reducing film of the present invention.

FIG. 2 is a schematic cross-sectional view of a marine drag reducing film of the present invention.

FIG. 3 is a schematic view of a marine drag reducing membrane of the present invention.

Fig. 4 is a schematic view (in isometric view) of the application of the marine drag reduction film of the present invention to the bottom of a ship.

In the figure: 1. a stable gas film layer formed by a longitudinal groove 2 and a micro-channel 3, a ship body 4 and a drag reduction film 5

Note: the dashed lines represent channels inside the membrane for gas flow.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

referring to fig. 1, 2, 3 and 4. The invention relates to a marine drag reduction film, the detailed structure of which is shown in figure 1. The membrane is made of Polytetrafluoroethylene (PTFE) and is divided into two surfaces. One surface mainly comprises two parts of a groove 1 and a micro-channel 2, wherein the grooves are uniformly distributed along the longitudinal direction of the ship bottom; the bottom of the ship body is provided with micropores, the bottom of the groove of the anti-drag film is provided with a microchannel 2, and the microchannel 2 is communicated with an air source in the ship body through the micropores at the bottom of the ship body so as to continuously output air. The other side is not etched with grooves, and the back glue is adopted to fix the film at the bottom of the ship. Specifically, as shown in fig. 2, the outer surface of the membrane is provided with a sawtooth-shaped groove, and the front part of the membrane is provided with a small hole and communicated with the small hole at the bottom of the ship; after gas is separated out from a gas source in the ship, the gas permeates into the grooves at the bottom of the ship, the generation of a gas film is controlled by utilizing the hydrophobic characteristic of the polytetrafluoroethylene surface structure and the constraint of the grooves, the distribution of the ventilation pore canals is controlled through the wetting step effect, so that one part of the ventilation pore canals generates gas while the other part does not generate gas, the stable existence of the ventilation pore canals in a period of time is ensured, and the existence time of the ventilation pore canals is prolonged as far as possible. Simultaneously, because the existence of air film and slot, filths such as some mud dirt in the sea water also can be isolated outside the hull bottom to realize antifouling effect. In addition, due to the problem of relatively low gas content of the gas film caused by the wetting step effect, gas is required to be supplemented at regular intervals so as to form a stable gas film on the bottom surface of the ship and reduce the resistance. When the film is prepared, the polytetrafluoroethylene resin is pre-pressed into a film shape by adopting an etching method, and the microporous film with a groove structure is formed by etching after sintering and forming, as shown in figure 3. Fig. 4 is a schematic view of the film applied to the bottom of a ship.