A device for measuring drag reduction effect based on closed pipes

Abstract

This invention discloses a device for measuring the drag reduction effect of a closed pipeline, comprising a water tank, a flow rate controller, a water pump, and a testing mechanism. The testing mechanism includes a testing channel, a testing plate, and several clamping structures. The bottom surface of the testing plate has a protrusion, and the bottom surface of the protrusion has several drag-reducing grooves. The testing plate is detachable and replaceable on the testing channel. In this invention, by setting up a testing mechanism and installing a replaceable testing plate on the testing mechanism, when water flows into the testing channel at a constant speed, the drag reduction effect of the testing plate can be measured by comparing the data from two pressure sensors on both sides of the testing channel. Therefore, by replacing the testing plate with one of different shapes of drag-reducing grooves, the drag reduction effect can be tested.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resistance measurement, and particularly relates to a drag reduction effect measuring device based on a closed pipeline. BACKGROUND

[0002] With the ocean strategy becoming an important strategy of China, the development of marine equipment gradually becomes a focus of attention. Different vehicles, including ships and submarines, will cause great energy loss due to resistance when running in the ocean. In order to better help the operation of the marine vehicle, a variety of underwater drag reduction methods need to be tested.

[0003] Traditional drag reduction calibration methods include physical experiments, rotating resistance measurement, drag resistance measurement and direct jet flow measurement. The above methods have certain limitations. The physical experiment involves a large ship or other vehicle, which is difficult to test and has many uncontrollable factors, and it is difficult to obtain the direct law of drag reduction method and drag reduction effect. The rotating resistance measurement adopts the method of measuring torque by driving the measured object with a motor. In this way, the measured resistance contains a series of interference such as mechanical transmission, and the result contains a large error. The drag resistance measurement can accurately obtain the resistance data, but the drag measurement requires a large site to prepare a water pool, and the drag equipment above the water pool needs to have the ability to run stably and constantly. In this case, the cost of each experiment is very huge. The direct jet flow method is an open measurement, which uses a nozzle to directly jet water flow to the plate. The cross-sectional area of the fluid cannot be constant, that is, the required Reynolds number cannot be guaranteed. In the drag reduction measurement, the Reynolds number is a key parameter to ensure the state of the fluid. In other words, this method cannot guarantee the required conditions, and therefore cannot guarantee the measurement accuracy.

[0004] In order to more efficiently, conveniently and low-costly complete the task of resistance measurement, the application provides a new device and measurement method to complete the related resistance measurement work.

[0005] The information disclosed in the background section of this document is intended only to increase an understanding of the general context of the present application, and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is already widely known in the art. SUMMARY

[0006] The application aims to provide a drag reduction effect measuring device based on a closed pipeline to solve the above problems in the prior art.

[0007] To achieve the above objectives, the present invention provides a drag reduction effect measuring device based on a closed pipeline, comprising a water tank filled with water, a flow rate controller and a water pump disposed at the top edge of the right inner wall of the water tank, and a testing mechanism disposed on the water tank. The testing mechanism includes a test channel fixed above the water tank, a test plate disposed at the top of the test channel, and several clamping structures fixed on the test channel. The right end of the test channel, the flow rate controller and the water pump are sequentially connected by a pipe, and the water inlet of the water pump is connected to the interior of the water tank by a pipe. The bottom surface of the test plate is provided with a protrusion that extends into the interior of the test channel, and the bottom surface of the protrusion is provided with several drag reduction grooves. The test plate is detachable and replaceable on the test channel.

[0008] In the technical solution of the present invention, a plurality of mounting plates are fixed between the inner walls of the front and rear sides of the top of the water tank, and a plurality of lugs are provided at the bottom edges of the front and rear sides of the test channel. The lugs and the test channel overlap the mounting plates, and the lugs are fixedly connected to the mounting plates.

[0009] In the technical solution of the present invention, the test channel has an internal cavity, and the front and rear edges of the top of the test channel are provided with protruding plates. The top surface of the protruding plate has a window, which is connected to the cavity. The test plate is attached to the protruding plate and covers the window. The protruding seat extends into the window.

[0010] In the technical solution of the present invention, an annular groove is provided at the periphery of the opening of the window, and a sealing ring is embedded in the annular groove, the sealing ring abutting against the bottom surface of the test plate.

[0011] In the technical solution of the present invention, a drain connector is provided at the top position of the left end of the test channel, and the drain connector is connected to the inside of the water tank by a pipe. A water inlet connector is provided at the top position of the right end of the test channel, and the water inlet connector is connected to the flow rate controller by a pipe.

[0012] In the technical solution of the present invention, pressure sensors are installed on both the left and right sides of the top of the test channel, the bottom surface of the pressure sensor is the detection surface, and the bottom surface of the pressure sensor is flush with the top wall of the cavity.

[0013] In the technical solution of the present invention, the test plate is fixed to the top of the test channel using the clamping structure. A plurality of clamping structures are distributed at the four edges of the test plate. The clamping structure includes a fixed seat fixed on the test channel, a threaded rod threadedly connected to the top of the fixed seat, and a stop block rotatably connected to the end of the threaded rod. The stop block abuts against the top edge of the test plate.

[0014] In the technical solution of the present invention, the top end of the fixed seat is inclined at 45° toward the direction of the abutting structure, the threaded rod passes through the top end of the fixed seat, the first end of the threaded rod is fixed with a lever, the end of the threaded rod is inserted into the abutment and installed on the abutment using a height-fixing bolt, and the bottom surface of the abutment is tightly bonded with a rubber plate.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0016] 1. In this invention, by setting up a testing mechanism and setting up a replaceable testing plate on the testing mechanism, when water flows into the testing channel at a constant speed, the resistance effect of the testing plate can be measured by comparing the data of two pressure sensors on both sides of the testing channel. Thus, the resistance reduction effect can be tested by replacing the testing plate with a test plate with a different shape of resistance reduction groove.

[0017] 2. In this invention, by using a testing mechanism on the water tank and connecting the water tank and the testing mechanism with a flow rate controller and a water pump, the water in the water tank can be injected into the testing channel through the water pump, and the flow rate of the injected water can be maintained under the control of the flow rate controller. This can maintain a constant testing environment in the testing channel and reduce testing errors. Attached Figure Description

[0018] Figure 1 This is a simplified schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is another overall structural diagram of the present invention;

[0020] Figure 3 This is a structural diagram of the water tank in this invention;

[0021] Figure 4 This is a structural diagram of the testing mechanism in this invention;

[0022] Figure 5 This is an exploded view of the test channel in this invention;

[0023] Figure 6 This is a cross-sectional view of the test channel in this invention;

[0024] Figure 7This is a diagram of the bottom structure of the test plate in this invention;

[0025] Figure 8 This is an exploded view of the clamping structure in this invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-Water tank; 11-Plate; 12-Fixing frame; 13-Flow rate controller; 14-Water pump;

[0028] 2-Testing mechanism; 21-Testing channel; 211-Cavity; 212-Protruding plate; 213-Window; 214-Annular groove; 215-Sealing ring; 216-Drainage connector; 217-Water inlet connector; 218-Pressure sensor; 219-Lug; 22-Testing plate; 221-Protruding seat; 222-Drag-reducing groove; 23-Clamping structure; 231-Fixed seat; 232-Threaded rod; 2321-Pulley; 233-Clamping block; 2331-Glue plate. Detailed Implementation

[0029] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0030] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0031] Reference Figures 1-8The drag reduction effect measuring device based on closed pipe of the present invention includes a water tank 1, which is filled with water. A flow rate controller 13 and a water pump 14 are provided at the top edge of the inner wall on the right side of the water tank 1. A testing mechanism 2 is also provided on the water tank 1. The testing mechanism 2 includes a testing channel 21 fixed above the water tank 1, a testing plate 22 provided at the top of the testing channel 21, and several clamping structures 23 fixed on the testing channel 21. The right end of the test channel 21, the flow rate controller 13, and the water pump 14 are connected in sequence by pipes. The water inlet of the water pump 14 is connected to the inside of the water tank 1 by a pipe. The test channel 21 has a cavity 211 inside. A drain connector 216 is provided at the top of the left end of the test channel 21. The drain connector 216 is connected to the inside of the water tank 1 by a pipe. A water inlet connector 217 is provided at the top of the right end of the test channel 21. The water inlet connector 217 is connected to the flow rate controller 13 by a pipe. When both the water pump 14 and the flow rate controller 13 are connected to an external power source, the water pump 14 draws water from the water tank 1 and pumps it into the flow rate controller 13 before entering the test channel 21. Finally, the water flows back to the water tank 1 from the left end of the test channel 21, forming a water circulation and providing a fluid environment for the entire test process.

[0032] In this invention, a mounting bracket 12 is fixed to the inner right side of the water tank 1, and a flow rate controller 13 is mounted on the mounting bracket 12. The flow rate controller 13 is a control valve that automatically adjusts the water flow rate to ensure the controllability of the flow rate in the entire fluid environment. The flow rate can be controlled according to the test requirements. Because the cross-section of the test channel 21 is a cross-section with a constant area, the velocity of the flow field can be accurately calculated based on the current flow rate. At the same time, under the action of the flow rate controller 13, the water flow injected into the test channel 21 is kept at a constant flow rate, thereby providing stable external conditions for the test in the test mechanism 2 and avoiding the situation where the test results are affected by the different flow rates of the water in the test channel 21.

[0033] Specifically, several mounting plates 11 are fixed between the inner walls of the front and rear sides of the top of the water tank 1. Several lugs 219 are provided at the bottom edges of the front and rear sides of the test channel 21. The test channel 21 is attached to the mounting plates 11 and the lugs 219 are fixedly connected to the mounting plates 11, so that the test mechanism 2 is fixed on the water tank 1 to prevent the test mechanism 2 from shaking during the test.

[0034] Furthermore, protruding plates 212 are provided at the front and rear edges of the top of the test channel 21. A window 213 is opened on the top surface of the protruding plate 212, communicating with the cavity 211. The test plate 22 rests on the protruding plate 212, covering the window 213. A protruding seat 221 is provided on the bottom surface of the test plate 22, extending into the window 213 and into the interior of the test channel 21. Several drag-reducing grooves 222 are opened on the bottom surface of the protruding seat 221, providing resistance to water flow within the test channel 21. The test plate 22 is detachable and replaceable on the test channel 21. By replacing the test plate 22 with one of different shapes and sizes of drag-reducing grooves 222 on the test channel 21, experimental and control groups can be set up according to different test plates 22, thus achieving the function of implementing different drag-reduction methods. Since different drag-reduction methods require different conditions, directly replacing the test plate 22 is faster and more efficient.

[0035] In addition, pressure sensors 218 are installed on the left and right sides of the top of the test channel 21. The bottom surface of the pressure sensor 218 is the detection surface, and the bottom surface of the pressure sensor 218 is flush with the top wall of the cavity 211 to prevent water from being resisted by the pressure sensor 218 when it flows through it. The two pressure sensors 218 can measure the pressure values ​​at the left and right ends of the test channel 21 respectively, so that the measured pressure values ​​can be compared and analyzed under different test plates 22.

[0036] In the above scheme, in order to keep the test channel 21 in a sealed environment, the test plate 22 is fixed to the top of the test channel 21 using a clamping structure 23. Several clamping structures 23 are distributed around the perimeter of the test plate 22. The clamping structure 23 includes a fixed seat 231 fixed on the test channel 21, a threaded rod 232 threadedly connected to the top of the fixed seat 231, and a stop block 233 rotatably connected to the end of the threaded rod 232. The stop block 233 abuts against the top edge of the test plate 22.

[0037] Specifically, the top of the fixed base 231 is inclined at 45° toward the direction of the clamping structure 23. The threaded rod 232 passes through the top of the fixed base 231. The first end of the threaded rod 232 is fixed with a lever 2321. The end of the threaded rod 232 is inserted into the abutment block 233 and installed on the abutment block 233 with a height-fixing bolt. When the test plate 22 is installed on the test channel 21, the lever 2321 is turned to rotate the threaded rod 232 and push the abutment block 233 downward. The abutment block 233 will finally abut against the top surface of the test plate 22, thereby fixing the test plate 22 on the test channel 21 and preventing the test plate 22 from falling off.

[0038] Furthermore, a rubber plate 2331 is tightly bonded to the bottom surface of the abutment block 233, and an annular groove 214 is provided at the outer periphery of the opening of the window 213. A sealing ring 215 is embedded in the annular groove 214. The sealing ring 215 abuts against the bottom surface of the test plate 22. When the abutment block 233 abuts against the top surface of the test plate 22, the rubber plate 2331 increases the resistance between the abutment block 233 and the test plate 22, so that the test plate 22 can be firmly abutted against the test channel 21. At this time, the sealing ring 215 plays a sealing role between the test channel 21 and the test plate 22, preventing water in the test channel 21 from leaking out from the window 213 and causing a decrease in the internal pressure of the test channel 21, thereby reducing test errors.

[0039] Furthermore, the energy loss under different conditions can be obtained by calculating the difference between the pressure interpolation values ​​of the two pressure sensors 218. This energy loss is mainly affected by frictional resistance, and its calculation formula is as follows:

[0040] η=((F_M1-F_M2)-(F_E1-F_E2)) / (F_M1-F_M2)×100%;

[0041] F_M1: Under control conditions, the force on the pressure sensor 218 near the water inlet connector 217;

[0042] F_M2: Under control conditions, the force on pressure sensor 218 near drain connector 216;

[0043] F_E1: Under experimental conditions, the force on pressure sensor 218 near water inlet connector 217;

[0044] F_E2: Under the experimental conditions, the force of the pressure sensor 218 near the drain connector 216.

[0045] The working principle of the drag reduction effect measuring device based on a closed pipe of the present invention is as follows: When a fluid flows through a plane, there will inevitably be energy loss. This energy loss is caused by the fluid overcoming the resistance of the plate. The lost energy is macroscopically manifested as a pressure drop before and after the fluid flows through the plate, that is, there is a pressure difference between the left and right ends of the test plate 22. By using test plates 22 with drag reduction grooves 222 of different shapes and sizes, test plates 22 with different mechanical properties can be obtained. Pressure sensors 218 are installed on the left and right sides of the test plate 22 respectively. The pressure sensor values ​​are transmitted to the PC host computer through a microcontroller. The PC can directly display the magnitude of the pressure difference. By comparing the measured value with the pressure difference value measured under the condition of a smooth bottom test plate 22, the drag reduction performance of different test models can be indirectly judged.

[0046] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A device for determining the drag reduction effect based on a closed conduit, comprising a water tank (1), characterized in that: The water tank (1) is filled with water, the top edge of the right side inner wall of the water tank (1) is provided with a flow rate controller (13) and a water pump (14), a test mechanism (2) is further arranged on the water tank (1), the test mechanism (2) comprises a test channel (21) fixed above the water tank (1), a test flat plate (22) arranged at the top end of the test channel (21) and a plurality of abutting structures (23) fixed on the test channel (21), the right end of the test channel (21), the flow rate controller (13) and the water pump (14) are sequentially connected by pipes, the water inlet end of the water pump (14) is connected with the inside of the water tank (1) by a pipe, the bottom surface of the test flat plate (22) is provided with a boss (221), the boss (221) extends into the inside of the test channel (21), a plurality of drag reduction grooves (222) are arranged on the bottom surface of the boss (221), and the test flat plate (22) is detachable and replaceable on the test channel (21). A cavity (211) is arranged in the inside of the test channel (21), the front and rear side edges of the top end of the test channel (21) are provided with a protruding plate (212), a window (213) is arranged on the top surface of the protruding plate (212), the window (213) is communicated with the cavity (211), the test flat plate (22) is overlapped on the protruding plate (212), and the window (213) is covered by the test flat plate (22), and the boss (221) extends into the window (213). A pressure sensor (218) is arranged at the left and right positions of the top end of the test channel (21), the bottom surface of the pressure sensor (218) is a detection surface, and the bottom end surface of the pressure sensor (218) is flush with the top wall of the cavity (211).

2. The closed tube based drag reduction effectiveness determination apparatus of claim 1, wherein: A plurality of battens (11) are fixed between the front and rear side inner walls of the top end of the water tank (1), a plurality of lugs (219) are arranged at the bottom end edges of the front and rear sides of the test channel (21), the test channel (21) is overlapped on the batten (11), and the lug (219) is fixedly connected with the batten (11).

3. The closed tube based drag reduction effectiveness determination apparatus of claim 2, wherein: An annular groove (214) is arranged at the peripheral part of the mouth of the window (213), a sealing ring (215) is embedded in the annular groove (214), and the sealing ring (215) abuts against the bottom surface of the test flat plate (22).

4. The closed tube based drag reduction effectiveness determination apparatus of claim 1, wherein: A drainage connector (216) is arranged at the top position of the left end of the test channel (21), the drainage connector (216) is connected with the inside of the water tank (1) by a pipe, and a water inlet connector (217) is arranged at the top position of the right end of the test channel (21), the water inlet connector (217) is connected with the flow rate controller (13) by a pipe.

5. The closed tube based drag reduction effectiveness determination apparatus of claim 1, wherein: The test plate (22) is fixed at the top end of the test channel (21) by the abutting structure (23), several abutting structures (23) are respectively arranged at the four peripheral edges of the test plate (22), the abutting structure (23) comprises a fixing base (231) fixed on the test channel (21), a threaded rod (232) threadedly connected with the top end of the fixing base (231), and an abutting block (233) rotatably connected with the end of the threaded rod (232), and the abutting block (233) abuts against the top edge of the test plate (22).

6. The enclosed tube based drag reduction effectiveness determination apparatus of claim 5, wherein: The top end of the fixing base (231) is inclined by 45° towards the direction of the abutting structure (23), the threaded rod (232) passes through the top end of the fixing base (231), the first end of the threaded rod (232) is fixed with a lever (2321), the end of the threaded rod (232) is inserted into the abutting block (233) and is installed on the abutting block (233) by using a height fixing bolt, and the bottom surface of the abutting block (233) is tightly bonded with a rubber plate (2331).

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