CN112556984B - Underwater model resistance measurement system and test method - Google Patents

Abstract

The invention provides an underwater model resistance measurement system, which includes a water tunnel test section and an underwater model, as well as a measuring device, a clamping device and a data acquisition card. The measuring device includes a base body, a connecting rod, an optical axis, and a pressure sensor. and a linear bearing, the optical axis is mounted on the base body through the linear bearing, the axis of the optical axis is parallel to the flow direction of the fluid in the water tunnel test section, and the connecting rod is connected to the optical axis , the connecting rod is connected with the underwater model through the clamping device, the pressure sensor is arranged on the base body along the fluid flow direction at the end of the optical axis, and the pressure sensor is connected with the data acquisition card , and the underwater model is provided with a counterweight block. The underwater model resistance measurement system provided by the invention can replace different clamping devices according to different shapes of underwater models, and has strong applicability.

Description

A kind of underwater model resistance measurement system and test method

technical field

The invention belongs to the field of resistance measurement of a water tunnel experimental device, and in particular relates to accurately obtaining the flow direction of the model under the high Reynolds number water tunnel test environment condition of a flat plate model, a ship vehicle model, a biological model, etc. The total resistance of the fluid in the direction, and the experimental system to carry out the research of drag reduction.

Background technique

The operating speed and work efficiency of the marine vehicle determine the performance of the vehicle. Besides the engine, the biggest influencing factor is the resistance during sailing. After more than half a century of research on the turbulent boundary layer, scholars have found that reducing the frictional resistance in the turbulent boundary layer is of great significance to engineering fields such as ships and underwater navigation. The resistance generated by the fluid when the object is immersed can be divided into the pressure difference resistance caused by the shape of the object and the friction resistance caused by the viscosity of the fluid itself. When the Reynolds number reaches a certain level, the fluid friction resistance will account for more than 50% of the total resistance, while This is mostly generated within the turbulent boundary layer. Therefore, controlling the turbulent boundary layer has become a hot spot in fluid drag reduction research, and the force measurement can intuitively compare the resistance, which is of great significance to the research of underwater model drag reduction.

At present, the measurement of underwater model resistance is usually tested in a circulating water tank, and its Reynolds number is usually low, which is far from practical application. However, to test in a closed high-speed circulating water tunnel, the sensor needs to be placed inside the water tunnel. The common method is to connect the sensor to the end of the model. The installation is complicated, and the center of gravity of the entire device moves forward, which is easy to generate vibration when the fluid passes through. Affect the measurement accuracy of the test data.

Therefore, there is an urgent need for a resistance measurement system that can adapt to underwater models with high Reynolds numbers.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a resistance measurement system for underwater models, which can adapt to a higher Reynolds number, and can clamp models of various shapes and lengths for resistance measurement.

The technical scheme adopted in the present invention is an underwater model resistance measurement system, which includes a water tunnel test section and an underwater model, as well as a measuring device, a clamping device and a data acquisition card. The measuring device includes a base body, a connecting rod, a An optical axis, a pressure sensor and a linear bearing, the optical axis is mounted on the base body through the linear bearing, the axis of the optical axis is parallel to the flow direction of the fluid in the water tunnel test section, and the optical axis is connected to There is the connecting rod, the connecting rod is connected with the underwater model through the clamping device, the pressure sensor is arranged on the base body along the fluid flow direction at the end of the optical axis, and the pressure sensor is connected to the underwater model. The data acquisition card is connected, and the underwater model is provided with a counterweight block.

Further, the optical axis is also provided with a return spring for restoring.

Further, the head and tail of the base body along the fluid flow direction are semi-cylindrical, the number of the optical axes is two, and two parallel cylindrical holes are arranged side by side in the base body, and the two cylindrical holes are arranged side by side. Both ends are provided with the linear bearings, the two optical axes are respectively installed in the linear bearings in the two cylindrical holes, and the substrate is located downstream of the two cylindrical holes along the fluid flow direction. An installation groove, the pressure sensor is installed in the sensor installation groove, a small shaft is extended from the end of the optical axis along the fluid flow direction, and a small shaft is arranged between the cylindrical hole and the installation groove. The small hole is matched, the small hole is provided with a sealing ring, the small shaft can be contacted with the pressure sensor through the small hole, and a return spring is sleeved on the small shaft, and one end of the return spring is capped. On the step of the optical axis, the other end rests on the base body, the connecting rod is T-shaped as a whole, and the top of the connecting rod is symmetrically provided with two circular holes matched with the optical axis. The circular hole of the connecting rod is provided with a locking screw along the radial direction, the connecting rod is sleeved on the optical axis through the circular hole, and is locked by the locking screw, the optical axis Two connecting rods are arranged on the upper part along the fluid flow direction in the water tunnel test section, and the lower ends of the connecting rods pass through the base body and are connected to the clamping device.

Further, a silicone pad is attached to the cylindrical hole of the base body at the linear bearing, and the cylindrical hole is provided with a set screw in a radial direction.

Further, the base body further includes a cover plate, the cover plate is mounted on the bottom of the base body, a square hole is formed on the cover plate, and the connecting rod passes through the square hole to connect with the clamping device.

The present invention also provides a test method for the above-mentioned underwater model resistance measurement system, including:

The first step is to install the measuring device on the upper wall of the water tunnel test section, the data acquisition card is installed outside the water tunnel test section, and connect the pressure sensor and the data acquisition card;

The second step is to install the underwater model on the connecting rod through the clamping device, and adjust the mass of the counterweight so that the overall density of the underwater model is within the range of the water tunnel test. The fluids are basically equal;

The third step: start the water tunnel test section to make the fluid circulate, push the underwater model and drive the optical axis inside the measuring device, so that the tail end touches the pressure sensor, the data acquisition card Collect and record the resistance data of the underwater model;

The fourth step is to replace the underwater models with different shapes or different surface structures, and repeat the third step to compare the resistance data of the different underwater models to obtain a test conclusion.

beneficial effect

The present invention has the following advantages:

The measurement and installation position of the underwater model resistance measurement system provided by the present invention can select any position of the model to balance the overall center of gravity and reduce the vibration caused during the experiment; Strong applicability; the two optical axes are arranged in parallel to reduce the vibration in the spanwise direction, and accurately measure the overall resistance of the underwater model along the flow direction under the action of the fluid; the head and tail of the measuring device are semi-cylindrical The shape design can reduce the disturbance of the pressure gradient sudden change on the flow field structure, and improve the authenticity and validity of the measurement data; the overall size of the measuring device is small, which can further reduce the impact on the flow field structure and improve the measurement accuracy; the material of the present invention can be made of aluminum Alloy, using the same and mature processing technology, easy to process and manufacture.

Description of drawings

1 is a schematic diagram of installation according to an embodiment of the present invention;

Fig. 2 is the front view of the measuring device in the embodiment of the present invention;

Fig. 3 is the bottom view of the measuring device in the embodiment of the present invention;

Fig. 4 is the left side view of the measuring device in the embodiment of the present invention;

5 is a schematic diagram of a cover plate in an embodiment of the present invention;

6 is a schematic diagram of an underwater model in an embodiment of the present invention;

In the figure, 1 is the water tunnel test section, 2 is the measuring device, 3 is the underwater model, 4 is the clamping device, 5 is the data acquisition card, 21 is the base, 22 is the connecting rod, 23 is the optical axis, and 24 is the pressure Sensor, 25 is a cover plate, 26 is a linear bearing, 31 is a counterweight, 221 is a locking screw, 231 is a return spring, 242 is a data cable, 243 is a sealing ring, 251 is a square hole, 261 is a set screw, 262 is a silicone pad.

Detailed ways

The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

As shown in FIG. 1 , an underwater model resistance measurement system includes a water tunnel test section 1 and an underwater model 3 , as well as a measurement device 2 , a clamping device 4 and a data acquisition card 5 .

As shown in FIG. 2 , FIG. 3 , FIG. 4 and FIG. 6 , the measuring device 2 includes a base body 21 , a connecting rod 22 , an optical axis 23 , a pressure sensor 24 and a linear bearing 26 , and the optical axis 23 passes through the linear bearing 26 is installed on the base body 21, the axis of the optical axis 23 is parallel to the fluid flow direction in the water tunnel test section 1, the optical axis 23 is connected with the connecting rod 22, and the connecting rod 22 passes through the test section 1. The clamping device 4 is connected to the underwater model 3 , the pressure sensor 24 is provided on the base 21 along the fluid flow direction at the end of the optical axis 23 , and the pressure sensor 24 is connected to the The data acquisition card 5 is connected, and the underwater model 3 is provided with a counterweight 31 . The pressure sensor 24 is an underwater load cell suitable for normal temperature and normal pressure environment.

As shown in FIG. 2 , FIG. 3 and FIG. 4 , the head and tail of the base body 21 along the fluid flow direction are semi-cylindrical, the number of the optical axes 23 is two, and the base body 21 is provided with two side by side. There are parallel cylindrical holes, both ends of the two cylindrical holes are provided with the linear bearings 26, and the two optical axes 23 are respectively installed in the linear bearings 26 in the two cylindrical holes, so The substrate 21 is provided with a sensor installation groove downstream of the two cylindrical holes along the fluid flow direction, the pressure sensor 24 is installed in the sensor installation groove, and the optical axis 23 extends along the fluid flow direction with a small shaft at the end of the fluid flow direction, Between the cylindrical hole and the installation slot, there is a small hole matching with the small shaft, and a sealing ring 243 is arranged on the small hole to achieve waterproof sealing, and the small shaft can pass through the small hole. In contact with the pressure sensor 24, a return spring 231 is sleeved on the small shaft. The rod 22 is T-shaped as a whole, the top of the connecting rod 22 is symmetrically provided with two circular holes matching the optical axis 23, and the circular holes of the connecting rod 22 are provided with locking locks in the radial direction. Screw 221, the connecting rod 22 is sleeved on the optical axis 23 through the circular hole, and is locked by the locking screw 221, the optical axis 23 is along the fluid in the water tunnel test section 1 The flow direction is provided with two connecting rods 22 , and the lower ends of the connecting rods 22 pass through the base body 21 and are connected to the clamping device 4 .

As shown in FIG. 2 , FIG. 3 and FIG. 4 , silicone pads 262 are attached to the cylindrical hole of the base body 21 at the linear bearing 26 , and the two cylindrical holes are approximately 3/4 cylindrical , the linear bearing 26 is also provided with a 1/4 gap. The cylindrical hole is radially provided with a set screw 261 , and the linear bearing 26 is opened to the outside and fixed by the set screw 261 . The silicone pad 262 is attached to achieve fine adjustment in the spanwise direction. Lubricating oil can be added to the set screw 261 to lubricate the linear bearing 26 , and the optical axis 23 can slide freely in the linear bearing 26 by adjusting the set screw 261 .

As shown in FIG. 2 and FIG. 5 , the base body 21 further includes a cover plate 25 , the cover plate 25 is mounted on the bottom of the base body 21 , and a square hole 251 is opened on the cover plate 25 , and the connecting rod 22 is formed from the The square hole 251 penetrates through and is connected to the clamping device 4 . The addition of the cover plate 25 is convenient for installation and can form a complete surface, reducing the influence on the flow field.

testing method

The test method of the above-mentioned underwater model resistance measurement system includes:

The first step is to install the measuring device 2 on the upper wall of the water tunnel test section 1, the data acquisition card 5 is installed outside the water tunnel test section 1, and connect the pressure sensor 24 to the Data acquisition card 5;

The second step is to install the underwater model 3 on the connecting rod 22 through the clamping device 4, and adjust the mass of the counterweight 31 to make the overall density of the underwater model 3 match the The fluids in the water tunnel test 1 are basically equal;

The third step is to start the water tunnel test section 1 to make the fluid circulate, push the underwater model 3 and drive the optical axis 23 inside the measuring device 2, so that its tail end touches the pressure sensor 24, The data acquisition card 5 collects and records the resistance data of the underwater model 3;

The fourth step is to replace the underwater models 3 with different shapes or surface structures, and repeat the third step to compare the resistance data of the different underwater models 3 to obtain a test conclusion.

The above are only preferred embodiments of the present invention, and do not have any limiting effect on the present invention. Any person skilled in the art, within the scope of not departing from the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, all belong to the technical solution of the present invention. content still falls within the protection scope of the present invention.

Claims (4)

1. An underwater model resistance measurement system, comprising a water tunnel test section (1) and an underwater model (3), characterized in that: also comprising a measuring device (2), a clamping device (4) and a data acquisition card ( 5), the measuring device (2) comprises a base body (21), a connecting rod (22), an optical axis (23), a pressure sensor (24) and a linear bearing (26), the optical axis (23) passing through the The linear bearing (26) is mounted on the base body (21), the axis of the optical axis (23) is parallel to the flow direction of the fluid in the water tunnel test section (1), and the optical axis (23) is connected with a The connecting rod (22) is connected to the underwater model (3) through the clamping device (4), and the base body (21) is located on the optical axis along the fluid flow direction The pressure sensor (24) is provided at the end of (23), the pressure sensor (24) is connected with the data acquisition card (5), and the underwater model (3) is provided with a counterweight (31); The head and tail of the base body (21) along the fluid flow direction are semi-cylindrical, the number of the optical axes (23) is two, and two parallel cylindrical holes are arranged in the base body (21) side by side, Both ends of the two cylindrical holes are provided with the linear bearings (26), and the two optical axes (23) are respectively installed in the linear bearings (26) in the two cylindrical holes, so The substrate (21) is provided with a sensor installation groove downstream of the two cylindrical holes along the fluid flow direction, the pressure sensor (24) is installed in the sensor installation groove, and the end of the optical axis (23) along the fluid flow direction A small shaft is extended, a small hole matched with the small shaft is arranged between the cylindrical hole and the installation groove, a sealing ring (243) is arranged on the small hole, and the small shaft passes through the small shaft. The small hole can be in contact with the pressure sensor (24), a return spring (231) is sleeved on the small shaft, one end of the return spring (231) is pressed against the step of the optical axis (23), and the other One end rests on the base body (21), the connecting rod (22) is T-shaped as a whole, and the top of the connecting rod (22) is symmetrically provided with two circular holes matched with the optical axis (23). , the circular hole of the connecting rod (22) is provided with a locking screw (221) in the radial direction, and the connecting rod (22) is sleeved on the optical axis (23) through the circular hole, And locked by the locking screw (221), the optical axis (23) is provided with two connecting rods (22) along the flow direction of the fluid in the water tunnel test section (1), the connecting rods (22). The lower end of the rod (22) passes through the base body (21) and is connected to the clamping device (4). 2 . The underwater model resistance measurement system according to claim 1 , wherein the cylindrical hole of the base body ( 21 ) and the linear bearing ( 26 ) are affixed with silicone pads ( 262 ). 3 . ), and the cylindrical hole is radially provided with a set screw (261). 3. The underwater model resistance measurement system according to claim 1, wherein the base body (21) further comprises a cover plate (25), and the cover plate (25) is installed on the base body (21) ) bottom, the cover plate (25) is provided with a square hole (251), and the connecting rod (22) passes through the square hole (251) and is connected to the clamping device (4). 4. the test method of a kind of underwater model resistance measurement system as described in any one of claim 1 to 3, is characterized in that, comprising: The first step is to install the measuring device (2) on the upper wall of the water tunnel test section (1), and the data acquisition card (5) is installed outside the water tunnel test section (1) and connected to the pressure sensor (24) and the data acquisition card (5); The second step is to install the underwater model (3) on the connecting rod (22) through the clamping device (4), and adjust the mass of the counterweight (31) to make the underwater model (3) The overall density of the lower model (3) is basically equal to the fluid in the water tunnel test section (1); The third step is to start the water tunnel test section (1) to circulate the fluid, push the underwater model (3) and drive the optical axis (23) inside the measuring device (2) to make its tail end Touching the pressure sensor (24), the data acquisition card (5) collects and records the resistance data of the underwater model (3); The fourth step is to replace the underwater models (3) with different shapes or surface structures, repeat the third step, compare the resistance data of the different underwater models (3), and obtain the test conclusion.

Images