CN-115266018-B - Circulating water tank experimental device and method for realizing flow field refractive index matching

CN115266018BCN 115266018 BCN115266018 BCN 115266018BCN-115266018-B

Abstract

The invention discloses a circulating water tank experimental device for realizing refractive index matching of a flow field, which comprises a vacuum pump, a first transmission unit, a centrifugal pump and a second transmission unit which are sequentially connected, wherein the second transmission unit is connected with the vacuum pump to form a closed circulating water tank, the vacuum pump is used for vacuumizing the closed circulating water tank, the centrifugal pump is used for driving solution in the closed circulating water tank to circularly flow, a structural object model for placing a to-be-tested is formed on the second transmission unit, and a test section capable of projecting a light source is formed on the second transmission unit, and the solution is a fluid working medium capable of enabling the test section to be matched with the solution in the same refractive index. The invention mainly provides a method for reducing the influence of different refractive indexes of light rays at a solid-liquid interface on the test result of an internal test piece (a structural object model) by selecting a specific fluid working medium to enable the refractive index of the fluid working medium to be the same as that of a test section.

Inventors

WANG YIWEI
WANG JINGZHU
Wang Guanghang
DU TEZHUAN

Assignees

中国科学院力学研究所
中国科学院力学研究所

Dates

Publication Date: 20260421
Application Date: 20220616
Priority Date: 20210616

Claims (6)

1. A circulating water tank experimental method for realizing flow field refractive index matching is characterized in that, The circulating water tank experimental device comprises a vacuum pump (3), a first transmission unit (1), a centrifugal pump (4) and a second transmission unit (2) which are sequentially connected, wherein the second transmission unit (2) is connected with the vacuum pump (3) to form a closed circulating water tank, the vacuum pump (3) is used for vacuumizing the closed circulating water tank, and the centrifugal pump (4) is used for driving solution in the closed circulating water tank to circularly flow; Forming a test section (5) which is used for placing a structure model to be tested and can project a light source on the second transmission unit (2), wherein the solution is a fluid working medium which can enable the test section (5) to be matched with the solution in the same refractive index; The fluid working medium is a NaI solution, and the NaI solution can have the same refractive index as the test section (5) at a preset temperature and a preset mass concentration; the structure model is used for testing a peripheral flow field of the structure model, and the refractive index of the structure model is the same as that of the test section; A temperature control unit is arranged on the second transmission unit (2) and is used for regulating and controlling the temperature of the fluid working medium to finely adjust the refractive index of the fluid working medium so as to enable the refractive index to be matched with the refractive index of the test section (5); The second transmission unit (2) comprises a rectifying section (27), a first gradual change pipe (24), a test section (5), a second gradual change pipe (25) and a special-shaped section (26) which are sequentially connected, wherein the rectifying section (27) is arranged close to the centrifugal pump (4), and the special-shaped section (26) is arranged close to the vacuum pump (3), and the first gradual change pipe (24) is used for enlarging a water flow channel flowing out of the test section (5) so as to reduce the solution pressure in the test section (5); The second gradual change pipe (25) slows down the water flow entering the test section (5); the special-shaped section (26) is used for transiting an incoming flow field in the second gradual change pipe (25); The rectifying section (27) is used for adjusting a flow field; The temperature control unit comprises a temperature regulating pipeline arranged in the rectifying section (27), and a cold water circulating system and a hot water circulating system which are arranged outside the water tank experimental device, wherein the cold water circulating system and the hot water circulating system both form a closed loop circulating waterway with the temperature regulating pipeline; the experimental method comprises the following steps: Step 100, according to the refractive index of a test section and the positive correlation relation between the refractive index and the mass concentration and the temperature of the solution, pre-matching the NaI solution with the preset mass concentration and the preset temperature so that the refractive index of the NaI solution is equal to the refractive index of the test section at the preset mass concentration and the preset temperature; step 200, calculating a difference relation between a concentration difference value between the actual mass concentration and the preset mass concentration and a temperature difference value between the actual temperature and the preset temperature according to the correlation; step 300, vacuumizing by a vacuum pump, forming a vacuum state in the closed circulating water tank, sealing and introducing a preset amount of NaI solution, and starting a centrifugal pump to drive the NaI solution in the closed circulating water tank to circularly flow; step 400, monitoring the mass concentration and the temperature of NaI solution in the closed circulating water tank in real time; When the temperature is lower than the preset temperature, starting a hot water circulation system to adjust the NaI solution to the preset temperature; When the mass concentration is lower than the preset mass concentration, adding the NaI into the closed circulating water tank until the NaI reaches the preset mass concentration, or calculating according to a difference value between the current mass concentration and the preset mass concentration and the difference value relation to obtain a first compensation temperature capable of enabling the refractive index of the NaI solution to be matched with the refractive index of a test section, and starting a hot water circulating system to adjust the NaI solution to the first compensation temperature; when the mass concentration is higher than the preset mass concentration, calculating to obtain a second compensation temperature capable of enabling the refractive index of the NaI solution to be matched with the refractive index of the test section according to the difference value between the current mass concentration and the preset mass concentration and the difference value relation, and starting a cold water circulation system to adjust the NaI solution to the second compensation temperature so as to balance the refractive indexes of the test section and the NaI solution to be the same; and 500, forming a NaI solution circulating flow under stable conditions in the closed circulating water tank so as to provide a stable simulation environment for the application simulation test of the structural model.
2. The method for realizing flow field refractive index matching circulating water channel experiment according to claim 1, wherein, The test section (5) is one section of the second transmission unit (2), the test section (5) is transparent, and the test section (5) is also used for observing the condition of the structure model in the test section during the test.
3. The method for realizing flow field refractive index matching circulating water channel experiment according to claim 2, wherein, The test section (5) is a high boron silicon hollow glass column.
4. A circulating water tank experimental method for realizing flow field refractive index matching is characterized in that, The circulating water tank experimental device comprises a vacuum pump (3), a first transmission unit (1), a centrifugal pump (4) and a second transmission unit (2) which are sequentially connected, wherein the second transmission unit (2) is connected with the vacuum pump (3) to form a closed circulating water tank, the vacuum pump (3) is used for vacuumizing the closed circulating water tank, and the centrifugal pump (4) is used for driving solution in the closed circulating water tank to circularly flow; Forming a test section (5) which is used for placing a structure model to be tested and can project a light source on the second transmission unit (2), wherein the solution is a fluid working medium which can enable the test section (5) to be matched with the solution in the same refractive index; The fluid working medium is a NaI solution, and the NaI solution can have the same refractive index as the test section (5) at a preset temperature and a preset mass concentration; the structure model is used for testing a peripheral flow field of the structure model, and the refractive index of the structure model is the same as that of the test section; A temperature control unit is arranged on the second transmission unit (2) and is used for regulating and controlling the temperature of the fluid working medium to finely adjust the refractive index of the fluid working medium so as to enable the refractive index to be matched with the refractive index of the test section (5); The second transmission unit (2) comprises a rectifying section (27), a first gradual change pipe (24), a test section (5), a second gradual change pipe (25) and a special-shaped section (26) which are sequentially connected, wherein the rectifying section (27) is arranged close to the centrifugal pump (4), and the special-shaped section (26) is arranged close to the vacuum pump (3), and the first gradual change pipe (24) is used for enlarging a water flow channel flowing out of the test section (5) so as to reduce the solution pressure in the test section (5); The second gradual change pipe (25) slows down the water flow entering the test section (5); the special-shaped section (26) is used for transiting an incoming flow field in the second gradual change pipe (25); The rectifying section (27) is used for adjusting a flow field; The temperature control unit comprises a temperature regulating pipeline arranged in the rectifying section (27), and a water chiller and a water heater which are arranged outside the water tank experimental device, wherein the water chiller and the water heater are connected with an external constant temperature circulating pipeline, the external constant temperature circulating pipeline is connected with the temperature regulating pipeline to form constant temperature water circulation which can always keep a set temperature, and the set temperature is realized through the cooperation regulation and control of the water chiller and the water heater; the experimental method comprises the following steps: Step 100, according to the refractive index of a test section and the positive correlation relation between the refractive index and the mass concentration and the temperature of the solution, pre-matching the NaI solution with the preset mass concentration and the preset temperature so that the refractive index of the NaI solution is equal to the refractive index of the test section at the preset mass concentration and the preset temperature; step 200, calculating a difference relation between a concentration difference value between the actual mass concentration and the preset mass concentration and a temperature difference value between the actual temperature and the preset temperature according to the correlation; step 300, vacuumizing by a vacuum pump, forming a vacuum state in the closed circulating water tank, sealing and introducing a preset amount of NaI solution, and starting a centrifugal pump to drive the NaI solution in the closed circulating water tank to circularly flow; 400, forming constant-temperature water circulation with preset temperature in the temperature-regulating pipeline through the water chiller and the water heater so as to keep the preset temperature of NaI solution in the closed circulating water tank; step 500, monitoring the mass concentration of NaI solution in the closed circulating water tank in real time; When the mass concentration is lower than the preset mass concentration, adding the NaI into the closed circulating water tank until the NaI reaches the preset mass concentration, or calculating according to a difference value between the current mass concentration and the preset mass concentration and the difference value relation to obtain a third compensation temperature capable of enabling the refractive index of the NaI solution to be matched with the refractive index of a test section, and starting the water chiller and the water heater to adjust the temperature in the constant-temperature water circulation to the third compensation temperature; when the mass concentration is higher than the preset mass concentration, calculating according to a difference value between the current mass concentration and the preset mass concentration and the difference value relation to obtain a fourth compensation temperature capable of enabling the refractive index of the NaI solution to be matched with the refractive index of a test section, and starting the water chiller and the water heater to adjust the temperature in the constant-temperature water circulation to the fourth compensation temperature so as to balance the refractive indexes of the test section and the NaI solution to be the same; And 600, forming a NaI solution circulating flow under stable conditions in the closed circulating water tank so as to provide a stable simulation environment for the application simulation test of the structural model.
5. The method for realizing flow field refractive index matching circulating water channel experiment according to claim 4, wherein, The test section (5) is one section of the second transmission unit (2), the test section (5) is transparent, and the test section (5) is also used for observing the condition of the structure model in the test section during the test.
6. The method for realizing flow field refractive index matching circulating water channel experiment according to claim 5, wherein, The test section (5) is a high boron silicon hollow glass column.

Description

Circulating water tank experimental device and method for realizing flow field refractive index matching Technical Field The invention relates to the technical field of hydrodynamic experiment devices, in particular to a circulating water tank experiment device and method for realizing flow field refractive index matching. Background The hydrodynamics faces a plurality of unsteady complicated flow measurement problems, the circulating water tank is a dynamic experiment device, can be used for researching problems of boundary layers, turbulence, cavitation, wake flow and the like, and is mainly a closed circulating water tank (with controllable parameters such as temperature) in consideration of the fact that parameters such as pressure, temperature, flow and flow rate in the water tank can be finely controlled. Based on the water tank experimental device, PIV technology is provided to realize analysis of various flowing velocity fields and further analyze the mechanism. Whereas PIV technology requires the acquisition of velocity distribution information (pictures) over a large number of spatial points of the same transient record by means of lighting, and provides rich flow field spatial structure and flow characteristics. Whether the light is uniformly distributed in the flow field is a prerequisite for acquiring the speed distribution information. The light source of the closed circulation water tank is projected from the outside, and the solid-liquid interface between the test section (observation part) and the solution and the solid-liquid interface between the test piece (structure model) and the solution are different in refractive index from the test piece to the test section, and reflection and scattering phenomena exist, so that the light at the structure model is not uniformly distributed, and even a part of the area is too dark, so that the test is difficult, and the smooth detail characteristics of the periphery of the structure are difficult to obtain. In summary, the closed water tank in the prior art is difficult to obtain data of flow field details at the near wall surface of the structure, and is difficult to obtain flow field detail characteristics of the inner side of the structure due to the influence of refraction, scattering and reflection of light rays when the structure is more complex. Disclosure of Invention The invention aims to provide a circulating water tank experimental device and a circulating water tank experimental method for realizing flow field refractive index matching, so as to solve the technical problems in the prior art. In order to solve the technical problems, the invention specifically provides the following technical scheme: In a first aspect of the invention, a circulation water tank experimental device for realizing refractive index matching of a flow field is provided, comprising a vacuum pump, a first transmission unit, a centrifugal pump and a second transmission unit which are sequentially connected, wherein the second transmission unit is connected with the vacuum pump to form a closed circulation water tank, the vacuum pump is used for vacuumizing the closed circulation water tank, and the centrifugal pump is used for driving solution in the closed circulation water tank to circularly flow; And forming a test section which is used for placing a structural object model to be tested and can project a light source on the second transmission unit, wherein the solution is a fluid working medium which can enable the test section to be matched with the solution in the same refractive index. As a preferable scheme of the invention, the fluid working medium is NaI solution, the refractive index of the NaI solution has positive correlation with temperature and mass concentration and has a peak value, and the NaI solution can be the same as the refractive index of the test section at the preset temperature and the preset mass concentration; the structure model is used for testing a peripheral flow field of the structure model, and the refractive index of the structure model is the same as that of the test section. As a preferable scheme of the invention, a temperature control unit is arranged on the second transmission unit and is used for regulating and controlling the temperature of the fluid working medium so as to finely adjust the refractive index of the fluid working medium to be matched with the refractive index of the test section. As a preferable mode of the invention, the test section is one section of the second transmission unit, the test section is transparent, and the test section is also used for observing the condition of the structural model in the test. As a preferable scheme of the invention, the test section is a high boron silicon hollow glass column. As a preferable scheme of the invention, the second transmission unit comprises a rectifying section, a first gradual change pipe, a test section, a second gradual change pipe and a special section