1. A fluid drag reduction effect testing device for realizing bionic surface structure transformation is characterized by comprising a water flow circulating system, a drag reduction effect testing device, a surface structure transformation device and a bionic structure test board;

the water flow circulating system comprises a test pipeline, two ends of the upper part of the test pipeline are provided with pipeline upper cover plates, and two ends of the bionic structure test plate are connected between the pipeline upper cover plates in a sliding manner;

the resistance reducing effect testing device comprises a main control platform, a change-over switch, a timer, a supporting plate, a supporting frame, a pressure control switch, a force transmission baffle, a magnet and an electromagnet; the electromagnet is integrated at the bottom of the main control platform and is connected with the upper cover plate of the pipeline; the change-over switch and the timer are installed on the main control platform; one end of the supporting plate is fixedly connected with the main control platform, and the other end of the supporting plate is fixedly arranged on the upper cover plate of the pipeline through the supporting frame; the magnet is fixed at one end, close to the electromagnet, of the bionic structure test board, the force transmission baffle is fixed at one end, far away from the electromagnet, of the bionic structure test board, and the surface structure transformation device is fixed on the bionic structure test board and located between the magnet and the force transmission baffle;

the pressure control switch is fixed on one side, close to the force transmission baffle, of the pipeline upper cover plate;

the change-over switch is used for simultaneously controlling the demagnetization of the electromagnet and the timing of the timer, and the voltage-controlled switch is used for realizing a signal for stopping the timing of the timer.

2. The device for testing the fluid drag reduction effect of realizing bionic surface structure transformation according to claim 1, wherein the surface structure transformation device is a concave-convex transformation device which comprises a first shell, a concave-convex telescopic rod, a concave-convex telescopic console, a concave-convex telescopic rod control assembly, an annular support ring, an annular divergent spring, a circular magnetic particle-containing cover film, an upper annular roller and a lower annular roller;

the bottom of the shell protrudes outwards and is fixed on the bionic structure test board, a plurality of circles of concave-convex telescopic rods are arranged in the shell, each concave-convex telescopic rod is provided with a telescopic rod control assembly, the bottom end of each circle of concave-convex telescopic rods is fixedly connected with an annular support ring, and the annular support ring is made of magnetic materials; the circular magnetic particle-containing cover film covers the surfaces of all the annular support rings from the bottom, and a circle of annular divergent springs extending along the radial direction are arranged on the periphery of the circular magnetic particle-containing cover film; one end of the annular divergent spring is fixed on the circular covering film containing magnetic particles, and the other end of the annular divergent spring is fixed on the bionic structure test board; the upper surface and the lower surface of the circular covering film containing magnetic particles and the position corresponding to the circular opening at the bottom of the shell are respectively provided with an upper annular roller and a lower annular roller, so that the circular covering film containing magnetic particles can be smoothly extended when extending inwards or outwards along with the annular supporting ring.

3. The fluid drag reduction effect testing device for realizing bionic surface structure transformation as claimed in claim 2, wherein the concave-convex telescopic rod control assembly comprises a shaft sleeve, a main gear, a left driving gear, a right driving gear, an upper bearing, a lower bearing, a first high-precision motor and a second high-precision motor, the main gear is mounted on the concave-convex telescopic rod through threaded connection, the upper end and the lower end of the main gear are respectively provided with the shaft sleeve, the end part of each shaft sleeve is supported on the concave-convex telescopic console, and the upper bearing and the lower bearing are respectively sleeved on the shaft sleeves to fix the main gear; the first high-precision motor and the second high-precision motor are respectively fixed on the concave-convex telescopic control platform and are positioned on the left side and the right side of the concave-convex telescopic rod, and the left driving gear and the right driving gear are respectively connected with the first high-precision motor and the second high-precision motor and are both meshed with the main gear;

the left driving gear and the right driving gear rotate simultaneously and stably drive the main gear to rotate, so that the concave-convex telescopic rod stretches under the action of threads.

4. The device for testing the fluid drag reduction effect of realizing the transformation of the bionic surface structure according to claim 3, wherein a concave-convex control panel is installed on the concave-convex telescopic control console, and a concave-convex USB access port and a concave-convex gear change button are integrated on the concave-convex control panel.

5. The fluid drag reduction effect testing device for realizing bionic surface structure transformation of claim 2, wherein the surface structure transformation device is a groove transformation device, which comprises a second shell, a groove telescopic rod control assembly, a rectangular support sheet, a rectangular magnetic particle-containing cover film, a rectangular divergent spring, an upper rectangular roller and a lower rectangular roller;

the bottom of the shell II protrudes outwards and is fixed on the bionic structure test board, a plurality of rows of groove telescopic rods are arranged in the shell II, each groove telescopic rod is provided with a groove telescopic rod control assembly, the lower end of each row of groove telescopic rods is fixedly connected with a rectangular support piece, and the rectangular support piece is made of a magnetic material; the rectangular magnetic particle-containing cover film covers all the rectangular support sheets from the bottom, and a circle of rectangular divergent springs extending along the radial direction are arranged on the periphery of the rectangular magnetic particle-containing cover film; one end of the rectangular divergent spring is fixed on the rectangular covering film containing magnetic particles, and the other end of the rectangular divergent spring is fixed on the bionic structure test board; the rectangular magnetic particle-containing cover film and the upper and lower surfaces of the rectangular opening at the two bottoms of the shell are respectively provided with a rectangular roller and a lower rectangular roller, so that the rectangular magnetic particle-containing cover film can be smoothly extended when being extended inwards or outwards along with the rectangular support sheet.

6. The device for testing the fluid drag reduction effect by realizing the transformation of the bionic surface structure as claimed in claim 5, wherein the groove telescopic rod control assembly and the concave-convex telescopic rod control assembly have the same structure and composition.

7. The device for testing the fluid drag reduction effect of realizing the transformation of the bionic surface structure according to claim 1, wherein a sliding groove is formed in the upper cover plate of the pipeline, a plurality of grooves are formed in the sliding groove, the bionic structure test plate slides along the sliding groove relative to the upper cover plate of the pipeline, and waterproof sealing is realized through the grooves.

8. The device for testing the fluid drag reduction effect by realizing the transformation of the bionic surface structure as claimed in claim 1, wherein the water circulation system comprises a large water tank, a main pipeline, an electromagnetic flowmeter, a test pipeline, an auxiliary pipeline, a first rectifier grid, a second rectifier grid, a small water tank, a power pipeline, a return pipeline, a water pump, a frequency converter and a motor; the large water tank, the main pipeline, the rectification grid II, the test pipeline, the rectification grid I, the auxiliary pipeline, the small water tank and the return pipeline are sequentially connected, one end of the power pipeline is communicated with the large water tank, the other end of the power pipeline is connected to a water outlet of the water pump, and one end of the return pipeline is connected to a water inlet of the water pump; the water pump is driven by the motor, and the flow speed is adjusted through the frequency converter.

9. A fluid drag reduction effect testing method for realizing bionic surface structure transformation is characterized in that the method is realized based on the device of claim 1, and the method specifically comprises the following steps:

(1) setting the bottom of the surface structure conversion device to form a smooth plane, shifting the change-over switch to a central position, electrifying the electromagnet to generate magnetism, attracting the magnet, and enabling the bionic structure test board to lean against the electromagnet under the action of magnetic force;

(2) the change-over switch is shifted from center to right, the electromagnet is demagnetized rapidly at the moment, the timer starts to time, the bionic structure test board moves rightwards under the action of fluid friction until the force transmission baffle touches the voltage-controlled switch, the voltage-controlled switch transmits a closing signal to the timer, and the recording time is t at the moment₁；

(3) Resetting the surface structure conversion device to be other structures, testing according to the same flow, and setting the timer to time t after the test is finished₂；

(4) According to t ═ t₂-t₁And judging the resistance reduction effect, wherein the larger t is, the better the resistance reduction effect is.

Background

When fluid flows on the surface of a solid, the surface of the solid generates frictional resistance. The power of the pump set in the fields of marine navigation, pipeline transportation and the like is mainly used for overcoming the frictional resistance between fluid and a wall surface. The surface frictional resistance of a conventional surface ship accounts for about 50% of the total resistance, the surface frictional resistance of an underwater vehicle even accounts for more than 70% of the total resistance, and according to theoretical calculation, under certain conditions of power and energy, the cruising speed and the range of the underwater vehicle can be increased by about 3.57% at the same time under the assumption that the resistance of the underwater vehicle is reduced by 10%. Therefore, the research on the resistance reducing technology can save a large amount of energy and improve the capacity utilization rate, and the current research on the resistance reducing technology mainly comprises non-smooth surface resistance reduction, micro-bubble resistance reduction, wall surface vibration resistance reduction, high polymer additive resistance reduction, bionic jet resistance reduction and the like. The non-smooth surface drag reduction has good drag reduction effect by simulation research on the characteristics of some organisms, is green and environment-friendly, and has great research significance and value.

In recent years, many biological surface structures have been found to be non-smooth, for example shark and dolphin skins have been distributed with many costal scale structures. The groove structures can change the structure and the speed distribution of a turbulent layer on the skin surface of the shark when the shark swims, and the groove drag reduction surface is inspired by the skin scutellum of the shark with excellent swimming capability. Besides, the pit and the convex hull are also important grooves and are inspired by the pit or convex hull structure on the surface of soil animals, and the surfaces of fish scales, whale fins and the like also have similar structures. Through researching the influence of the resistance reducing elements of the concave pit convex hull on the resistance reducing performance of the pipeline, the highest resistance reducing rate of the concave pit convex hull can reach 33.57%. Based on the above, the method optimizes and simulates the non-smooth biological structure characteristics of different biological surfaces, and then puts the characteristics optimized by simulation into a test, and sets a contrast test, so as to explore the resistance reduction effect which can be achieved by the different biological characteristics.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a fluid drag reduction effect testing device and method for realizing bionic surface structure transformation, which can be used for measuring the friction force between fluid and solid and evaluating the drag reduction effects of different groove shapes and concave pit convex hulls.

The purpose of the invention is realized by the following technical scheme:

a fluid drag reduction effect testing device for realizing bionic surface structure transformation comprises a water flow circulating system, a drag reduction effect testing device, a surface structure transformation device and a bionic structure test board;

the water flow circulating system comprises a test pipeline, two ends of the upper part of the test pipeline are provided with pipeline upper cover plates, and two ends of the bionic structure test plate are connected between the pipeline upper cover plates in a sliding manner;

the resistance reducing effect testing device comprises a main control platform, a change-over switch, a timer, a supporting plate, a supporting frame, a pressure control switch, a force transmission baffle, a magnet and an electromagnet; the electromagnet is integrated at the bottom of the main control platform and is connected with the upper cover plate of the pipeline; the change-over switch and the timer are installed on the main control platform; one end of the supporting plate is fixedly connected with the main control platform, and the other end of the supporting plate is fixedly arranged on the upper cover plate of the pipeline through the supporting frame; the magnet is fixed at one end, close to the electromagnet, of the bionic structure test board, the force transmission baffle is fixed at one end, far away from the electromagnet, of the bionic structure test board, and the surface structure transformation device is fixed on the bionic structure test board and located between the magnet and the force transmission baffle;

the pressure control switch is fixed on one side, close to the force transmission baffle, of the pipeline upper cover plate;

the change-over switch is used for simultaneously controlling the demagnetization of the electromagnet and the timing of the timer, and the voltage-controlled switch is used for realizing a signal for stopping the timing of the timer.

Furthermore, the surface structure conversion device is a concave-convex conversion device and comprises a first shell, a concave-convex telescopic rod, a concave-convex telescopic control console, a concave-convex telescopic rod control assembly, an annular support ring, an annular divergent spring, a circular magnetic particle-containing cover film, an upper annular roller and a lower annular roller;

the bottom of the shell protrudes outwards and is fixed on the bionic structure test board, a plurality of circles of concave-convex telescopic rods are arranged in the shell, each concave-convex telescopic rod is provided with a telescopic rod control assembly, the bottom end of each circle of concave-convex telescopic rods is fixedly connected with an annular support ring, and the annular support ring is made of magnetic materials; the circular magnetic particle-containing cover film covers the surfaces of all the annular support rings from the bottom, and a circle of annular divergent springs extending along the radial direction are arranged on the periphery of the circular magnetic particle-containing cover film; one end of the annular divergent spring is fixed on the circular covering film containing magnetic particles, and the other end of the annular divergent spring is fixed on the bionic structure test board; the upper surface and the lower surface of the circular covering film containing magnetic particles and the position corresponding to the circular opening at the bottom of the shell are respectively provided with an upper annular roller and a lower annular roller, so that the circular covering film containing magnetic particles can be smoothly extended when extending inwards or outwards along with the annular supporting ring.

Furthermore, the concave-convex telescopic rod control assembly comprises a shaft sleeve, a main gear, a left driving gear, a right driving gear, an upper bearing, a lower bearing, a first high-precision motor and a second high-precision motor, wherein the main gear is installed on the concave-convex telescopic rod through threaded connection, the upper end and the lower end of the main gear are respectively provided with the shaft sleeve, the end part of each shaft sleeve is supported on the concave-convex telescopic console, and the upper bearing and the lower bearing are respectively sleeved on the shaft sleeves to fix the main gear; the first high-precision motor and the second high-precision motor are respectively fixed on the concave-convex telescopic control platform and are positioned on the left side and the right side of the concave-convex telescopic rod, and the left driving gear and the right driving gear are respectively connected with the first high-precision motor and the second high-precision motor and are both meshed with the main gear;

the left driving gear and the right driving gear rotate simultaneously and stably drive the main gear to rotate, so that the concave-convex telescopic rod stretches under the action of threads.

Furthermore, install unsmooth control panel on the unsmooth flexible control cabinet, integrated unsmooth USB on the unsmooth control panel inserts mouth and unsmooth gear change button.

Furthermore, the surface structure conversion device is a groove conversion device and comprises a second shell, a groove telescopic rod control assembly, a rectangular support sheet, a rectangular magnetic particle-containing cover film, a rectangular divergent spring, an upper rectangular roller and a lower rectangular roller;

the bottom of the shell II protrudes outwards and is fixed on the bionic structure test board, a plurality of rows of groove telescopic rods are arranged in the shell II, each groove telescopic rod is provided with a groove telescopic rod control assembly, the lower end of each row of groove telescopic rods is fixedly connected with a rectangular support piece, and the rectangular support piece is made of a magnetic material; the rectangular magnetic particle-containing cover film covers all the rectangular support sheets from the bottom, and a circle of rectangular divergent springs extending along the radial direction are arranged on the periphery of the rectangular magnetic particle-containing cover film; one end of the rectangular divergent spring is fixed on the rectangular covering film containing magnetic particles, and the other end of the rectangular divergent spring is fixed on the bionic structure test board; the rectangular magnetic particle-containing cover film and the upper and lower surfaces of the rectangular opening at the two bottoms of the shell are respectively provided with a rectangular roller and a lower rectangular roller, so that the rectangular magnetic particle-containing cover film can be smoothly extended when being extended inwards or outwards along with the rectangular support sheet.

Further, the groove telescopic rod control assembly and the concave-convex telescopic rod control assembly are identical in structure and composition.

Furthermore, the pipeline upper cover plate is internally provided with a sliding groove, a plurality of grooves are formed in the sliding groove, and the bionic structure test board slides relative to the pipeline upper cover plate along the sliding groove and achieves waterproof sealing through the grooves.

Further, the water flow circulating system comprises a large water tank, a main pipeline, an electromagnetic flowmeter, a testing pipeline, an auxiliary pipeline, a first rectifying grid, a second rectifying grid, a small water tank, a power pipeline, a backflow pipeline, a water pump, a frequency converter and a motor; the large water tank, the main pipeline, the rectification grid II, the test pipeline, the rectification grid I, the auxiliary pipeline, the small water tank and the return pipeline are sequentially connected, one end of the power pipeline is communicated with the large water tank, the other end of the power pipeline is connected to a water outlet of the water pump, and one end of the return pipeline is connected to a water inlet of the water pump; the water pump is driven by the motor, and the flow speed is adjusted through the frequency converter.

A fluid drag reduction effect test method for realizing bionic surface structure transformation is realized based on the device, and the method specifically comprises the following steps:

(1) setting the bottom of the surface structure conversion device to form a smooth plane, shifting the change-over switch to a central position, electrifying the electromagnet to generate magnetism, attracting the magnet, and enabling the bionic structure test board to lean against the electromagnet under the action of magnetic force;

(2) the change-over switch is shifted from center to right, the electromagnet is demagnetized rapidly at the moment, the timer starts to time, the bionic structure test board moves rightwards under the action of fluid friction until the force transmission baffle touches the voltage-controlled switch, the voltage-controlled switch transmits a closing signal to the timer, and the recording time is t at the moment₁；

(3) Resetting the surface structure conversion device to be other structures, testing according to the same flow, and setting the timer to time t after the test is finished₂；

(4) According to t ═ t₂-t₁And judging the resistance reduction effect, wherein the larger t is, the better the resistance reduction effect is.

The invention has the following beneficial effects:

(1) the invention can realize the resistance reduction test of the concave pit convex hull models with different depths and curvatures and the conversion of the concave pit convex hull models with different groove depths and groove structure models, can simultaneously carry out the combination test of different concave pit convex hulls and groove models, and can also carry out the resistance reduction test on a single concave pit convex hull or groove model so as to meet the test requirement.

(2) The invention realizes measurement through the electromagnet and the timer, and finally reflects the resistance reduction effect through time, thereby being simple and clear, convenient to operate and capable of visually reflecting the resistance reduction effect of the test board surfaces with different structures.

(3) In the testing process, water is used as a fluid medium, and the water is recycled through the power supply device and the main flow circulating pipeline, so that the resource is saved, and the device is environment-friendly and pollution-free;

(4) the invention has the advantages of low cost, small occupied area, low noise, simple structure, convenient data acquisition, effective and intuitive reflection of the resistance reduction effect of various models, and quick and simple operation.

Drawings

FIG. 1 is a schematic diagram of the test apparatus;

FIG. 2 is a schematic diagram of a bump-to-bump converting apparatus;

FIG. 3 is a schematic view of a male and female telescoping rod control assembly;

FIG. 4 is an enlarged view of the ring-like divergent spring;

FIG. 5 is a cross-sectional view of a groove changing device;

FIG. 6 is a schematic bottom view of the annular support ring and the rectangular support sheet;

FIG. 7 is an enlarged view of the joint between the test of the bionic structure test board and the upper cover plate of the pipeline;

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the objects and effects of the present invention will become more apparent, it being understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

As shown in FIG. 1, the fluid drag reduction effect testing device for realizing the transformation of the bionic surface structure comprises a water flow circulating system, a convex hull and concave pit transformation device, a groove transformation device, a drag reduction effect testing device and a bionic structure test board 23.

The water flow circulating system comprises a main testing pipeline and a power supply device. The power supply device comprises a water pump 14, a motor 13 and a frequency converter 12. The main flow test pipeline comprises a large water tank 2, a main pipeline 27, an electromagnetic flowmeter 28, a test pipeline 20, an auxiliary pipeline 17, a first rectifying grid 18, a second rectifying grid 26, a small water tank 16, a power pipeline 3 and a return pipeline 15. The drag reduction effect testing device comprises a main control platform 4, a change-over switch 5, a timer 6, a supporting frame 7, a supporting plate 8, a pressure control switch 21, a force transmission baffle 22, a magnet 24 and an electromagnet 25. The concave-convex conversion device 9 comprises a concave-convex telescopic rod 9-1, a concave-convex telescopic control console 9-2, a concave-convex USB access port 9-3, a concave-convex gear change button 9-4, a concave-convex control panel 9-5, an annular support ring 9-6, an inner annular roller 9-7, an outer annular roller 9-8, a circular magnetic particle containing cover film 9-9, an annular divergent spring 9-10, a first shell 9-11 and an inner telescopic rod control assembly.

The groove conversion device 11 comprises a groove telescopic rod 11-1, a groove telescopic control platform 11-2, a groove USB access port 11-3, a groove gear conversion button 11-4, a groove control panel 11-5, a rectangular support sheet 11-6, an inner rectangular roller 11-7, an outer rectangular roller 11-8, a rectangular magnetic particle containing cover film 11-9, a rectangular divergent spring 11-10, a second shell 11-11 and an inner telescopic rod control assembly.

The main flow test pipeline comprises a cock 1, a large water tank 2, a main pipeline 27, an electromagnetic flowmeter 28, a test pipeline 20, a secondary pipeline 17, a first rectifying grid 18, a second rectifying grid 28, a small water tank 16, a power pipeline 3 and a return pipeline 15.

Referring to fig. 1, in the water circulation system, an output shaft of a motor 13 is connected with a water pump 14 through a coupler, the motor 13 is a YVP series variable frequency speed control three-phase asynchronous motor, and a frequency converter 12 is used for speed regulation. The water inlet of the water pump 14 is connected with the small water tank 16 through the return pipeline 15, and the water outlet of the water pump 14 is connected with the large water tank 2 through the power pipeline 3. The flow rate of the main flow channel 27, and thus the flow rate of the main flow field, can be controlled by adjusting the frequency converter 14.

The main flow test pipeline has the specific structure that: big water tank 2 is placed at the leftmost side, it has cock 1 to go up on it, power pipeline 3 is connected on 2 top right sides in big water tank, be connected with the liquid outlet of power supply unit's water pump 14 by power pipeline 3, power pipeline 3 is fixed on backup pad 8 through fixed plate 10, the inlet of water pump 14 meets with backflow pipeline 15, backflow pipeline 15's the other end is connected with little water tank 16, big water tank 2's bottom right side links to each other with trunk line 27, integrated electromagnetic flowmeter 28 on trunk line 27, the trunk line 27 other end is connected with test tube 20, test tube 20 entrance point and exit end install rectification bars two 28 respectively, rectification bars 18. The outlet end of the test pipeline 20 is connected with the small water tank 16 through the auxiliary pipeline 17, and the small water tank 16 is connected with the liquid inlet of the water pump 14 through the return pipeline 15 to form a waterway circulation system. When the test is carried out, the whole device is filled with liquid by opening the cock 1, the water flow power provided by the power supply device is controlled, and the water flow speed condition of the test pipeline 20 at the moment is observed through the electromagnetic flowmeter 28.

With reference to fig. 2, 3, 4, and 6, the specific structure of the bump packet converter 9 is: the bottom of the first shell 9-10 protrudes outwards and is fixed on the bionic structure test board 23, and a plurality of circles of concave-convex telescopic rods 9-1 are arranged in the first shell. The concave-convex telescopic rod 9-1 is connected with a concave-convex telescopic rod control component inside the concave-convex telescopic rod through a concave-convex telescopic control console 9-2, and the telescopic rod control component is as follows: the concave-convex telescopic rod 9-1 is connected with the main gear 9-14 through threads. The axial surface of the main gear 9-14 is fixedly provided with shaft sleeves 9-21 by welding, the upper and lower parts of the shaft sleeves 9-21 are respectively provided with upper bearings 9-15 and lower bearings 9-20, the types of the bearings are all selected from tapered roller bearings, the upper bearings 9-15 and the lower bearings 9-20 fix the main gear 9-14, the two sides of the main gear 9-14 are respectively provided with a left driving gear 9-23 and a right driving gear 9-18, the left driving gear 9-23 is connected with a high-precision motor I9-12 by a left driving shaft 9-22, and the high-precision motor I9-12 is connected with a concave-convex telescopic console 9-2 by a motor fixing rod I9-13. The right driving gear 9-18 is connected with a second high-precision motor 9-17 through a right driving shaft 9-19, and the second high-precision motor 9-17 is connected with a concave-convex telescopic control platform 9-2 through a second motor fixing rod 9-16. The left driving gear 9-23 and the right driving gear 9-18 rotate simultaneously and stably to drive the main gear 9-14 to rotate, so that the concave-convex telescopic rod 9-1 is stretched under the action of threads, and the stretching rod control assembly is arranged in the concave-convex telescopic rod. Concave-convex control boards 9-5 are installed on the concave-convex telescopic control platform 9-2, and concave-convex USB access ports 9-3 and concave-convex gear change buttons 9-4 are integrated on the concave-convex control boards 9-5. The bottom of the telescopic rod 9-1 is welded and fixed with the annular support ring 9-6, and the annular support ring 9-6 is made of magnetic materials. The surface of the annular supporting ring 9-6 is covered with a circular magnetic particle-containing covering film 9-9, a circle of divergent spring 9-10 is integrated on the periphery of the circular magnetic particle-containing covering film 9-9, the divergent spring 9-10 is hermetically connected with the inside of the bionic structure test board 23, and when the annular supporting ring 9-6 forms a supporting structure, the circular magnetic particle-containing covering film 9-9 changes along with the change of the circular magnetic particle-containing covering film, and meanwhile, the circular divergent spring 9-10 is driven to stretch and contract, so that the circular magnetic particle-containing covering film 9-9 covers the annular supporting ring 9-6. The upper and lower parts of the round covering film 9-9 containing magnetic particles, which correspond to the round opening at the bottom, are respectively provided with an upper annular roller 9-7 and a lower annular roller 9-8, and the function of the upper annular roller and the lower annular roller is that the round covering film 9-9 containing magnetic particles can smoothly extend when the round covering film 9-9 containing magnetic particles extends inwards or outwards along with the annular supporting ring 9-6.

The concave-convex hull model control method comprises the following steps: when a certain convex hull or pit model drag reduction effect test is required, pit convex hull modeling is performed through computer simulation modeling, and a plurality of convex hull pit modes are set and are led into each model in the concave-convex control panel 9-5 through the concave-convex USB access port 9-3 to correspond to one concave-convex gear change button 9-4. A concave-convex gear change button 9-4 corresponding to a needed concave-convex hull model is pressed, a concave-convex control panel 9-5 receives signals and controls a first high-precision motor 9-12 and a second high-precision motor 9-17 to operate simultaneously through a concave-convex telescopic control console 9-2, the first high-precision motor 9-12 and the second high-precision motor 9-17 control a left driving gear 9-23 and a right driving gear 9-18 to rotate in the same direction through a left driving shaft 9-22 and a right driving shaft 9-19 respectively so as to enable a main gear 9-14 connected with the left driving gear and the right driving gear to operate, and therefore the concave-convex telescopic rod 9-1 is driven to stretch and retract through threads. And the revolution number of the high-precision motor I9-12 and the high-precision motor II 9-17 is controlled by an algorithm to realize the change of the expansion amount of the telescopic rod 9-1, the concave-convex telescopic rod 9-1 is welded on the annular support ring 9-6, and a plurality of concave-convex telescopic rods 9-1 are welded on each annular support ring 9-6, and the annular support rings 9-6 can be stably lifted by adopting the same control. The bottom of the whole concave-convex bag conversion device is composed of a plurality of dense annular support rings 9-6 together, the stretching amount of the concave-convex telescopic rod 9-1 on each annular support ring 9-6 is quantitatively controlled, so that the stretching amount of each annular support ring 9-6 is changed, if the outward stretching amount of the annular support ring 9-6 at the outermost ring is minimum, the stretching amount of the annular support ring 9-6 at the innermost ring is maximum, and the plurality of annular support rings 9-6 in the middle uniformly form a step-type structure to be connected with the outermost ring and the innermost ring, a convex bag support structure required by people is formed. In the same way, an additional dimple and dimple support structure may be formed. And finally, the circular magnetic particle-containing cover film 9-9 on the surface of the concave pit or convex hull supporting structure formed by the plurality of annular supporting rings 9-6 extends to cover the supporting structure and is attached to the surface of the supporting structure through magnetic adsorption and water pressure action so as to realize surface sealing and smooth connection of the supporting structure formed by the annular supporting rings 9-6 and form a tested convex hull or concave pit structure.

The specific structure of the groove changing device 11 shown in fig. 5 and 6 is as follows: the bottom of the second shell 11-11 protrudes outwards and is fixed on the bionic structure test board 23, a plurality of rows of groove telescopic rods are arranged in the second shell, a groove USB access port 11-3 and a groove gear change button 11-4 are integrated on a groove control panel 11-5, and the groove control panel 11-5 is installed on a groove telescopic control platform 11-2. The groove telescopic rod 11-1 is connected with a groove telescopic rod control assembly inside the groove telescopic rod through a groove telescopic control platform 11-2, the bottom of the groove telescopic rod is welded with a rectangular supporting sheet 11-6, and threads are also embedded on the surface of the groove telescopic rod 11-1. The installation of the telescopic rod component in the concave-convex bag conversion device 9 is the same as the installation mode of the concave-convex telescopic rod 9-1 in the concave-convex bag conversion device 9. The rectangular magnetic particle-containing cover film 11-9 is covered on the surface of the rectangular supporting sheet 11-6, the rectangular divergent spring 11-10 is embedded at the periphery of the rectangular magnetic particle-containing cover film 11-9, when the rectangular supporting sheet 11-6 forms a supporting structure, the rectangular magnetic particle-containing cover film 11-9 extends, and the rectangular divergent spring 11-10 is driven to stretch, so that the rectangular magnetic particle-containing cover film 11-9 covers the formed supporting structure. The rectangular covering film 11-9 containing magnetic particles is connected with the inside of the bionic structure test plate 23 in a sliding sealing mode. The upper rectangular roller 11-6 and the lower rectangular roller 11-8 are respectively arranged at the upper part and the lower part of the rectangular covering film 11-9 containing magnetic particles corresponding to the rectangular opening at the bottom, and the function of the rectangular covering film 11-9 containing magnetic particles can be smoothly extended when the rectangular covering film 11-9 containing magnetic particles extends inwards or outwards along with the rectangular supporting sheet 11-6. The main structure of the groove conversion device 11 is similar to that of the concave-convex bag conversion device 9, the bottom of the groove conversion device is designed to be a rectangular support sheet 11-6 which is similar to a cuboid slice, but the groove conversion device is also made of a magnetic material, the rectangular support sheet 11-6 is controlled by controlling the groove telescopic rod 11-1, a groove structure is formed by converting the relative position of the rectangular support sheet 11-6, and a required test groove is formed by covering the rectangular magnetic particle-containing cover film 11-9.

The groove model control method comprises the following steps: the control principle is similar to the control method of the concave-convex bag model, and the main difference is that the supporting structure of the bottom is different. With reference to fig. 5 and 6, a groove model is established through simulation modeling, and several groove modes are set and introduced into the groove control panel 11-5 through the groove USB access port 11-3, wherein the groove model can be designed into a ladder shape, a triangle shape and the like. The groove telescopic control console 11-2 is started by pressing the corresponding groove gear change button 11-4, the telescopic control component inside is used for controlling the telescopic amount of the groove telescopic rod 11-1, and the control mode of the telescopic control component is the same as that of the concave-convex telescopic rod 9-1. The rectangular support pieces 11-6 are sheet-shaped, similar to a cube slice, each rectangular support piece 11-6 is attached to each other, a plurality of telescopic rods are mounted on each rectangular support piece 11-6 and operate simultaneously to stably control the relative expansion amount of each rectangular support piece 11-6 and the expansion amount of the bionic structure test board 23, and the bottom of the whole groove conversion device 11 is designed into the dense rectangular support pieces 11-6 to jointly form a gradient support structure by controlling the expansion amount of the telescopic rods of different rectangular support pieces 11-6. For example, the plurality of middle rectangular support sheets 11-6 have the highest and equal outward stretching amount, the rectangular support sheets 11-6 on the two sides have the smallest stretching amount, and the rest rectangular support sheets 11-6 are sequentially and uniformly connected with the rectangular support sheets 11-6 on the two sides and the rectangular support sheet 11-6 in the middle to form a trapezoidal groove support structure, as shown in fig. 5. And finally, the rectangular covering film 11-9 containing the magnetic particles extends along with the supporting structure, covers the gradient supporting structure and is attached to the surface of the supporting structure under the action of magnetic adsorption and water pressure so as to realize the sealing and smooth transition of the surface of the gradient supporting structure to form the required groove testing structure.

With reference to fig. 1, the specific structure of the drag reduction effect testing device is as follows: the change-over switch 5 and the timer 6 are integrated on the main control platform 4. Change over switch 5 divides three fender position, and electro-magnet and time-recorder do not all work when living left side, and the electro-magnet circular telegram when centering, and the time-recorder timing is lived right in the right side, and 4 bottoms of master control platform are equipped with electro-magnet 25 and connect mutually through waterproof sealant with pipeline upper cover plate 19 and fix on its surface, and with 24 laminating of magnet when not starting, magnet 24 dress is at the most left end of bionic structure test panel. The left end of the supporting plate 8 is welded on the main control platform 4 and is fixedly connected through the supporting rod 7, the right lower end of the supporting plate 8 is fixed on the upper cover plate 19 of the pipeline, and the left side of the supporting plate is provided with the voltage-controlled switch 21. The tail end of the bionic structure test board is provided with a force transmission baffle 22, the electromagnet 25 is controlled to be demagnetized rapidly and the timer 6 is controlled to time at the same time through the change-over switch 5 during the resistance reduction effect test, the signal that the timer stops timing is realized through the pressure control switch 21, and the resistance reduction effect is reflected through the time.

The resistance reducing effect test method comprises the following steps: when the flow rate is fixed by combining the flow rate shown in figure 1, a smooth plane is formed at the bottom of an annular supporting structure of a pit conversion device 9 and a gradient supporting structure of a groove conversion device 11 and the bottom of a bionic structure test board 23, a change-over switch 5 is shifted to a central position, an electromagnet 25 is electrified to generate magnetism at the moment and attracts a magnet 24, the bionic structure test board 23 leans against the leftmost end under the action of magnetic force, the change-over switch 5 is shifted from the central position to the right position, the electromagnet 25 is demagnetized rapidly at the moment, a timer 6 starts to time, the bionic structure test board 23 moves rightwards under the action of friction force of a fluid, the bionic structure test board passes through a force transmission baffle 22 until a touched voltage control switch 21, the voltage control switch 21 transmits a closing signal to the timer 6, and the time is t at the moment₁The ring-shaped supporting structure of the pit changer 9 and the gradient supporting structure of the groove changer 11 are retested and set to be other structures, the test is performed according to the same flow, and the test completion timer 6 counts t₂. Let t be t₂-t₁The larger t, the better the drag reduction effect.

The device is sealed in combination with the device shown in fig. 7, the telescopic part of the upper cover plate 19 of the pipeline and the bionic structure test plate 23 is designed to be provided with a step-type sealing structure with a regular geometric shape, the longitudinal rectangular groove structure of the step-type sealing structure is provided with the step-type sealing structure around the sliding area of the two, a sealing groove is formed, a series of regular throttling gaps and expansion cavities are formed when the bionic structure test plate 23 slides, and step-by-step throttling effect is generated through viscous friction of media and energy conversion, so that sealing is realized. Similarly, the connection extension part of the circular magnetic particle-containing cover film 9-9 and the bionic structure test plate 23 shown in fig. 4 is also designed to be a stepped sealing structure with a regular geometric shape, and in addition, the connection extension part of the rectangular magnetic particle-containing cover film 11-9 and the bionic structure test plate 23 is also of the same structure.

The working principle of the whole device is as follows: when the device uses, annotate liquid in the big water tank 2 through opening cock 1 earlier, make whole mainstream circulation pipeline be full of liquid, later close cock 1 and adjust through converter 12 to among the power supply unit to the rotational speed of control motor 13 realizes controlling water pump running power, and then accomplishes and control the mainstream test pipeline velocity of flow, and reads through electromagnetic flowmeter 28, sets for the different velocity of flow operating modes in the test pipeline 20. Then, the concave-convex hull model control method and the groove model control method are used for realizing the transformation of the concave-convex hull transformation device 9 and the groove transformation device 11 and controlling the test concave-convex hull and the groove structure of the bionic structure test board 23. And finally, evaluating the resistance reducing effect of various testing concave-convex hulls and grooves by using a resistance reducing effect testing method.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and although the invention has been described in detail with reference to the foregoing examples, it will be apparent to those skilled in the art that various changes in the form and details of the embodiments may be made and equivalents may be substituted for elements thereof. All modifications, equivalents and the like which come within the spirit and principle of the invention are intended to be included within the scope of the invention.