A circulating water tank experimental device and method for realizing flow field refractive index matching

Abstract

This invention discloses a circulating water tank experimental apparatus for achieving refractive index matching of a flow field. It includes a vacuum pump, a first transmission unit, a centrifugal pump, and a second transmission unit connected in sequence. The second transmission unit is connected to the vacuum pump to form a closed circulating water tank. The vacuum pump is used to evacuate the closed circulating water tank, and the centrifugal pump is used to drive the solution within the closed circulating water tank to circulate. A test section is formed on the second transmission unit for placing the structural model to be tested and for projecting a light source. The solution is a fluid medium that allows the test section to match the same refractive index as the solution. The main point of this invention is to reduce the impact of different refractive indices at the solid-liquid interface on the test results of the internal test piece (structural model) by selecting a specific fluid medium with the same refractive index as the test section.

Description

Technical Field

[0001] This invention relates to the field of fluid mechanics experimental apparatus technology, specifically to a circulating water tank experimental apparatus and method for achieving flow field refractive index matching. Background Technology

[0002] Fluid mechanics faces many unsteady and complex flow measurement problems. Circulating water tanks are a type of dynamic experimental equipment that can be used to study boundary layers, turbulence, cavitation, wakes, and other issues. Considering that parameters such as pressure, temperature, flow rate, and velocity within the tank can be precisely controlled, most circulating water tanks are closed (with controllable parameters, such as temperature).

[0003] Based on the water tank experimental setup, PIV (Portable Image Transmission) technology is incorporated to analyze the velocity fields of various flows and, consequently, their mechanisms. PIV technology requires illumination to acquire velocity distribution information (images) at a large number of spatial points in the same transient state, providing rich spatial structures and flow characteristics of the flow field. Uniform distribution of light within the flow field is a prerequisite for obtaining velocity distribution information.

[0004] The light source of the closed circulating water tank needs to be projected from the outside. At the solid-liquid interface between the test section (observation part) and the solution, and at the solid-liquid interface between the test piece (structural model) and the solution, due to the different refractive indices of the solution and the test piece and test section, and the existence of reflection and scattering phenomena, the light distribution at the structural model is uneven, and some areas are even too dark, which makes it difficult to conduct tests and difficult to obtain smooth details around the structure.

[0005] In summary, existing closed water tank technologies make it difficult to acquire detailed flow field data near the wall of a structure. Furthermore, for more complex structures, the refraction, scattering, and reflection of light make it difficult to obtain detailed flow field features inside the structure. Summary of the Invention

[0006] The purpose of this invention is to provide a circulating water tank experimental apparatus and method for achieving flow field refractive index matching, so as to solve the technical problems in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0008] In a first aspect of the present invention, a circulating water tank experimental apparatus for achieving flow field refractive index matching is provided, comprising a vacuum pump, a first transmission unit, a centrifugal pump and a second transmission unit connected in sequence, wherein the second transmission unit is connected to the vacuum pump to form a closed circulating water tank, the vacuum pump is used to evacuate the closed circulating water tank, and the centrifugal pump is used to drive the solution in the closed circulating water tank to circulate.

[0009] In this process, a test section is formed on the second transmission unit for placing a model of the structure to be tested and for projecting a light source, and the solution is a fluid working medium that can match the test section with the same refractive index as the solution.

[0010] In a preferred embodiment of the present invention, the working fluid is a NaI solution. The refractive index of the NaI solution is positively correlated with both temperature and mass concentration, and has a peak value. The refractive index of the NaI solution is the same as that of the test section at a preset temperature and a preset mass concentration.

[0011] The structural model is used to test its peripheral flow field, and the structural model and the test section are set to have the same refractive index. As a preferred embodiment of the invention, a temperature control unit is provided on the second transmission unit. The temperature control unit is used to regulate the temperature of the working fluid to fine-tune the refractive index of the working fluid to match it with the refractive index of the test section.

[0012] In a preferred embodiment of the present invention, the test segment is a section of the second transmission unit, the test segment is transparent, and the test segment is also used to observe the condition of the internal structural model during testing.

[0013] In a preferred embodiment of the present invention, the test section is a high borosilicate hollow glass column.

[0014] In a preferred embodiment of the present invention, the second transmission unit includes a rectifier section, a first gradient tube, a test section, a second gradient tube, and a shaped section connected in sequence. The rectifier section is located near the centrifugal pump, and the shaped section is located near the vacuum pump. The first gradient tube is used to enlarge the water flow channel from the test section to reduce the solution pressure in the test section.

[0015] The second gradient tube slows down the water flow entering the test section;

[0016] The irregular section is used to transition the incoming flow field inside the second tapered tube;

[0017] The rectifying section is used to adjust the flow field.

[0018] As a preferred embodiment of the present invention, the temperature control unit includes a temperature regulating pipeline disposed within the rectifier section, and a cold water circulation system and a hot water circulation system disposed outside the water tank experimental device. Both the cold water circulation system and the hot water circulation system form a closed-loop circulating water circuit with the temperature regulating pipeline; and both the cold water circulation system and the hot water circulation system are capable of regulating the temperature of their supplied water.

[0019] As a preferred embodiment of the present invention, the temperature control unit includes a temperature regulating pipeline disposed within the rectifier section, and a chiller and a hot water heater disposed outside the water tank experimental device. The chiller and the hot water heater are connected to an external constant temperature circulation pipeline. The external constant temperature circulation pipeline is connected to the temperature regulating pipeline to form a constant temperature water circulation that can always maintain the set temperature. The set temperature is achieved by the coordinated control of the chiller and the hot water heater.

[0020] In a second aspect of the present invention, a circulating water tank experimental method for achieving flow field refractive index matching based on the above-described experimental apparatus is also provided, comprising the following steps:

[0021] Step 100: Based on the refractive index of the test section and the positive correlation between the refractive index and the solution mass concentration and solution temperature, pre-match a NaI solution with a preset mass concentration and 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 preset temperature.

[0022] Step 200: Based on the aforementioned correlation, calculate the relationship between the concentration difference between the actual mass concentration and the preset mass concentration and the temperature difference between the actual temperature and the preset temperature;

[0023] Step 300: The vacuum pump draws a vacuum to form a vacuum state in the closed circulating water tank, and a preset amount of NaI solution is introduced into the tank. At the same time, the centrifugal pump is started to drive the NaI solution in the closed circulating water tank to circulate.

[0024] Step 400: Monitor the mass concentration and temperature of the NaI solution in the closed circulating water tank in real time;

[0025] When the temperature is lower than the preset temperature, the cold water circulation system is activated to adjust the NaI solution to the preset temperature; when the temperature is higher than the preset temperature, the hot water circulation system is activated to adjust the NaI solution to the preset temperature.

[0026] When the mass concentration is lower than the preset mass concentration, add NaI to the closed circulating water tank until it reaches the preset mass concentration, or calculate the first compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula, and activate the hot water circulation system to adjust the NaI solution to the first compensation temperature.

[0027] When the mass concentration is higher than the preset mass concentration, a second compensation temperature is calculated based on the difference between the current mass concentration and the preset mass concentration, and the relationship between the difference, so that the refractive index of the NaI solution can be matched to the refractive index of the test section. The cold water circulation system is then activated to adjust the NaI solution to the second compensation temperature, so as to balance the refractive indices of the test section and the NaI solution to make them the same.

[0028] Step 400: Until a stable NaI solution circulation flow is formed in the closed circulating water tank, a stable simulation environment is provided for the application simulation test of the structural model.

[0029] In a third aspect of the present invention, a circulating water tank experimental method for achieving flow field refractive index matching based on the above-described experimental apparatus is also provided, comprising the following steps:

[0030] Step 100: Based on the refractive index of the test section and the positive correlation between the refractive index and the solution mass concentration and solution temperature, pre-match a NaI solution with a preset mass concentration and 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 preset temperature.

[0031] Step 200: Based on the aforementioned correlation, calculate the relationship between the concentration difference between the actual mass concentration and the preset mass concentration and the temperature difference between the actual temperature and the preset temperature;

[0032] Step 300: The vacuum pump draws a vacuum to form a vacuum state in the closed circulating water tank, and a preset amount of NaI solution is introduced into the tank. At the same time, the centrifugal pump is started to drive the NaI solution in the closed circulating water tank to circulate.

[0033] Step 400: The chiller and the water heater form a constant temperature water circulation at a preset temperature in the temperature control pipeline to maintain the preset temperature of the NaI solution in the closed circulating water tank.

[0034] Step 500: Real-time monitoring of the mass concentration of the NaI solution in the closed circulating water tank.

[0035] When the mass concentration is lower than the preset mass concentration, NaI is added to the closed circulating water tank until it reaches the preset mass concentration, or the third compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula, and the chiller and the hot water machine are started to adjust the temperature in the constant temperature water circulation to the third compensation temperature.

[0036] When the mass concentration is higher than the preset mass concentration, the fourth compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula. The chiller and the hot water machine are then activated to adjust the temperature in the constant temperature water circulation to the fourth compensation temperature in order to balance the refractive indices of the test section and the NaI solution to make them the same.

[0037] Step 600: Until a stable NaI solution circulation flow is formed in the closed circulating water tank, a stable simulation environment is provided for the application simulation test of the structural model.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] This invention mainly proposes to reduce the impact of different refractive indices of light at the solid-liquid interface on the test results of the internal test piece (structural model) by selecting a specific working fluid that has the same refractive index as the test section.

[0040] This invention further proposes a control method for changes in refractive index caused by variations in fluid concentration and / or temperature. This method can adjust the refractive index of the solution in a closed circulating water tank online to match the refractive index of the structural model and the test section, thereby providing a stable testing environment. This reduces the impact of different refractive indices at the solid-liquid interface on the simulation test, enhances the acquisition of data on the flow field details near the wall of the structure, and also reduces the influence of light refraction, scattering, and reflection on the structure. This allows for the acquisition of even more refined flow field details on the inner side of the structure. Attached Figure Description

[0041] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of the circulating water tank experimental device of the present invention;

[0043] Figure 2 This is a schematic diagram of the overall temperature control scheme of the present invention.

[0044] Figure 3 This is a schematic diagram of the flow around a cylinder taken by a PIV with the refractive index matched according to the present invention;

[0045] Figure 4A schematic diagram of the flow around a cylinder using a PIV with an unmatched refractive index according to the present invention;

[0046] Figure 5 This is a schematic diagram of the flow around the cylinder during the PIV experiment of glass cylinder refractive index matching (after removing the cylinder edge) of the present invention.

[0047] The labels in the diagram:

[0048] The labels in the diagram:

[0049] 1. First transmission unit; 2. Second transmission unit; 3. Vacuum pump; 4. Centrifugal pump; 5. Test section; 6. Flow metering unit; 7. Support frame;

[0050] 11. First curved section; 111. Fifth transmission port; 112. Sixth transmission port; 12. Second curved section; 121. First inclined section; 122. Seventh transmission port; 123. Eighth transmission port; 13. First kneading section;

[0051] 21. Extension section; 211. Sealing component; 22. Third gradient tube; 221. Ninth transmission port; 222. Tenth transmission port; 223. Third pipe wall; 23. Vent valve; 24. First gradient tube; 241. Second transmission port; 242. First pipe wall; 243. First transmission port; 25. Second gradient tube; 251. Third transmission port; 252. Second pipe wall; 253. Fourth transmission port; 26. Irregular section; 261. Fourth pipe wall; 262. Fifth pipe wall; 263. First pipe opening; 264. Second pipe opening; 27. Rectifying section; 271. Honeycomb unit; 272. Damping mesh; 28. Second joint section;

[0052] 51. First observation unit entrance; 52. Observation frame; 53. Transparent observation window; 54. Dissolved oxygen measurement equipment; 55. Second observation unit entrance. Detailed Implementation

[0053] The following will refer to the appendices in the embodiments of the present invention. Figure 1 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0054] like Figure 1As shown, this invention provides a circulating water tank experimental device for achieving flow field refractive index matching. Essentially, it proposes a method based on existing closed circulating water tank experimental devices that can reduce / solve the problems caused by uneven light distribution and poor light in some areas due to the different light refraction at the solid-liquid interface and the existence of reflection and scattering phenomena, which in turn lead to the inability to accurately obtain the surrounding fine flow field.

[0055] The circulating water tank experimental device generally includes a vacuum pump 3, a first transmission unit 1, a centrifugal pump 4 and a second transmission unit 2 connected in sequence. The second transmission unit 2 is connected to the vacuum pump 3 to form a closed circulating water tank. The vacuum pump 3 is used to evacuate the closed circulating water tank, and the centrifugal pump 4 is used to drive the solution in the closed circulating water tank to circulate.

[0056] In this system, a test section 5 is formed on the second transmission unit 2 for placing the structural model to be tested and for projecting a light source. The solution is a fluid working medium with the same refractive index as the test section 5. The structural model is used to test its peripheral flow field.

[0057] This embodiment first proposes to match the refractive index of the test section with that of the solution to solve the problem of the difference in refractive index at the solid-liquid interface before the light source is projected onto the structure. It is mainly applicable to test pieces with relatively simple structures, because for test pieces with relatively simple structures, the impact on the uniformity of light distribution is actually relatively small.

[0058] Although on the surface this embodiment only adds a refractive index matching scheme for the test section and the solution, it is not easy to obtain. In the actual experimental process, the difficulties include: the environment is subject to change, the selection of the solution, the relationship between the refractive index of the solution and the test section and environmental parameters (concentration, temperature, etc.), so the control scheme when changes occur cannot be accurately obtained, and it is difficult to obtain through in-depth analysis and experimentation.

[0059] The working fluid is any general solution that can meet the test conditions and match the refractive index of the test section. The refractive index of the solution is positively correlated with temperature and mass concentration, and has a peak value (that is, when the temperature and concentration are high enough, the refractive index no longer changes). In this embodiment, NaI solution is preferred because it is non-toxic. As far as we know, other suitable solutions are at least slightly toxic.

[0060] Similarly, the refractive index of the NaI solution can be the same as that of the test section (5) at a preset temperature and preset mass concentration. The preset temperature and preset mass concentration are obtained through preliminary experiments. In fact, the refractive index of the NaI solution has a positive linear relationship with temperature and mass concentration.

[0061] In order to expand the applicability of the experimental apparatus and make it suitable for more complex test specimens (structural models), this embodiment further provides that the structural model and the test section are set to the same refractive index, preferably the test section and the structural model are made of the same material.

[0062] After the refractive index data is pre-matched, the closed-loop operation preparation of the water tank device is completed. Afterwards, the temperature of the NaI solution will change due to time and external factors, and the concentration may also change (with relatively small impact). In this regard, this application further provides a temperature control scheme, which is mainly used to regulate the temperature parameters of the NaI solution.

[0063] The specific solution is as follows: a temperature control unit is provided on the second transmission unit 2. The temperature control unit is used to regulate the temperature of the fluid working medium to fine-tune the refractive index of the fluid working medium so that it matches the refractive index of the test section 5.

[0064] Preferably, the test segment 5 is a section of the second transmission unit 2, the test segment 5 is transparent, and the test segment 5 can also be used to observe the internal structural model during testing. Further, the test segment 5 is a high borosilicate hollow glass column.

[0065] Since the solution mass concentration and temperature are both positively correlated with the refractive index, the control scheme for environmental changes can be obtained through experimental simulation and / or calculation. The main difficulties, in addition to those mentioned above, are that when the concentration changes, it is not easy to control the solution concentration online in a closed-loop water tank device. The specific solution is the temperature control unit as shown below, as well as the two experimental methods proposed later.

[0066] In order to reduce the problem of unstable flow field or excessive pressure in the test section during the experiment, the second transmission unit 2 of the experimental device is configured to include a rectifier section 27, a first gradient tube 24, a test section 5, a second gradient tube 25 and a shaped section 26 connected in sequence. The rectifier section 27 is located close to the centrifugal pump 4 and the shaped section 26 is located close to the vacuum pump 3.

[0067] The first gradient tube 24 is used to enlarge the water flow channel from the test section 5 to reduce the solution pressure in the test section 5; the second gradient tube 25 slows down the water flow entering the test section 5; the irregular section 26 is used to transition the incoming flow field in the second gradient tube 25; and the straightening section 27 is used to adjust the flow field.

[0068] The following provides two temperature control schemes to achieve the regulation of solution temperature from different perspectives.

[0069] Temperature control scheme one: The temperature control unit includes a temperature regulating pipeline installed in the rectifier section (27) (the flow field of the rectifier section is relatively stable), and a cold water circulation system and a hot water circulation system installed outside the water tank experimental device. The cold water circulation system and the hot water circulation system form a closed-loop circulating water circuit with the temperature regulating pipeline; and the cold water circulation system and the hot water circulation system can regulate the temperature of their supplied water.

[0070] This scheme mainly uses independent heating and cooling operations to regulate the temperature of the water circulating in the temperature control pipeline, thereby exchanging heat with the solution and controlling the solution temperature.

[0071] In this scheme, the water temperature in the temperature control pipeline can be selected according to the difference between the current temperature of the solution and the preset temperature (the temperature that matches the refractive index). For example, when the difference is large, a larger water temperature can be selected, which can achieve the purpose of regulation more quickly. The same principle applies when the difference is small.

[0072] However, this method relies on water temperature monitoring to ensure the end of the control process, and slight variations are possible. Nevertheless, it is sufficient to meet the requirements, and the differences are negligible. It is mainly suitable for tests with relatively minor environmental influences (e.g., when the solution temperature is close to room temperature), where further temperature changes are not significant.

[0073] Of course, after temperature adjustment, one of the circulation loops can be set to form a water circulation loop with the same preset temperature (the temperature when the refractive index is matched) and kept at that temperature, or kept at the same circulation loop as the target temperature that should be controlled according to calculation.

[0074] Temperature control scheme two: The temperature control unit includes a temperature regulating pipe installed in the rectifier section 27, and a chiller and a hot water heater installed outside the water tank experimental device. The chiller and the hot water heater are connected to an external constant temperature circulation pipe. The external constant temperature circulation pipe is connected to the temperature regulating pipe to form a constant temperature water circulation that can always maintain the set temperature. The set temperature is achieved by coordinating and regulating the chiller and the hot water heater.

[0075] The solution mainly involves establishing an external constant-temperature water circulation system to maintain a circulation temperature that is either the same as the preset temperature or the same as the calculated target temperature that should be controlled.

[0076] This embodiment also includes a temperature monitoring and concentration monitoring device for detecting the temperature and concentration of the solution.

[0077] The main concept behind the temperature control solution is:

[0078] The water pump is running, and the solution is circulating.

[0079] The solution temperature T1 is compared with the temperature T2 of the circulating water cooling pipe system (temperature control unit). When T1 is greater than T2, T2 is increased, and vice versa, T2 is decreased until T1 = T2 before the test begins.

[0080] Specifically, for temperature control scheme one, this embodiment provides a circulating water tank experimental method for achieving flow field refractive index matching, including the following steps:

[0081] Step 100: Based on the refractive index of the test section and the positive correlation between the refractive index and the solution mass concentration and solution temperature, pre-match a NaI solution with a preset mass concentration and 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 preset temperature.

[0082] Step 200: Based on the aforementioned correlation, calculate the relationship between the concentration difference between the actual mass concentration and the preset mass concentration and the temperature difference between the actual temperature and the preset temperature;

[0083] Step 300: The vacuum pump draws a vacuum to form a vacuum state in the closed circulating water tank, and a preset amount of NaI solution is introduced into the tank. At the same time, the centrifugal pump is started to drive the NaI solution in the closed circulating water tank to circulate.

[0084] Step 400: Monitor the mass concentration and temperature of the NaI solution in the closed circulating water tank in real time;

[0085] When the temperature is lower than the preset temperature, the cold water circulation system is activated to adjust the NaI solution to the preset temperature; when the temperature is higher than the preset temperature, the hot water circulation system is activated to adjust the NaI solution to the preset temperature.

[0086] When the mass concentration is lower than the preset mass concentration, add NaI to the closed circulating water tank until it reaches the preset mass concentration, or calculate the first compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula, and activate the hot water circulation system to adjust the NaI solution to the first compensation temperature.

[0087] When the mass concentration is higher than the preset mass concentration, a second compensation temperature is calculated based on the difference between the current mass concentration and the preset mass concentration, and the relationship between the difference, so that the refractive index of the NaI solution can be matched to the refractive index of the test section. The cold water circulation system is then activated to adjust the NaI solution to the second compensation temperature, so as to balance the refractive indices of the test section and the NaI solution to make them the same.

[0088] Step 500: Until a stable NaI solution circulation flow is formed in the closed circulating water tank, a stable simulation environment is provided for the application simulation test of the structural model.

[0089] Specifically, for temperature control scheme two, this implementation scheme provides a circulating water tank experimental method to achieve flow field refractive index matching, including the following steps:

[0090] Step 100: Based on the refractive index of the test section and the positive correlation between the refractive index and the solution mass concentration and solution temperature, pre-match a NaI solution with a preset mass concentration and 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 preset temperature.

[0091] Step 200: Based on the aforementioned correlation, calculate the relationship between the concentration difference between the actual mass concentration and the preset mass concentration and the temperature difference between the actual temperature and the preset temperature;

[0092] Step 300: The vacuum pump draws a vacuum to form a vacuum state in the closed circulating water tank, and a preset amount of NaI solution is introduced into the tank. At the same time, the centrifugal pump is started to drive the NaI solution in the closed circulating water tank to circulate.

[0093] Step 400: The chiller and the water heater form a constant temperature water circulation at a preset temperature in the temperature control pipeline to maintain the preset temperature of the NaI solution in the closed circulating water tank.

[0094] Step 500: Real-time monitoring of the mass concentration of the NaI solution in the closed circulating water tank.

[0095] When the mass concentration is lower than the preset mass concentration, NaI is added to the closed circulating water tank until it reaches the preset mass concentration, or the third compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula, and the chiller and the hot water machine are started to adjust the temperature in the constant temperature water circulation to the third compensation temperature.

[0096] When the mass concentration is higher than the preset mass concentration, the fourth compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula. The chiller and the hot water machine are then activated to adjust the temperature in the constant temperature water circulation to the fourth compensation temperature in order to balance the refractive indices of the test section and the NaI solution to make them the same.

[0097] Step 600: Until a stable NaI solution circulation flow is formed in the closed circulating water tank, a stable simulation environment is provided for the application simulation test of the structural model.

[0098] Both of these approaches have their advantages, and the appropriate approach should be chosen based on actual needs. In summary, this invention mainly proposes a control method for changes in refractive index caused by variations in fluid concentration and / or temperature. This method can adjust the refractive index of the solution in a closed circulating water tank online to match the refractive index of the structural model and the test section, thereby providing a stable testing environment. This reduces the impact of different refractive indices at the solid-liquid interface on the simulation test, enhances the acquisition of detailed flow field data near the wall of the structure, and also reduces the influence of light refraction, scattering, and reflection on the structure. This allows for the acquisition of even more refined detailed flow field features inside the structure.

[0099] The experimental apparatus and method of this invention can obtain detailed flow fields around the rod bundles under different rod bundle arrangement conditions and different flow rates. It allows observation of internal flow phenomena through some external surface structures, and better captures the flow details and overall picture of the entire field. Specific examples include... Figures 3 to 5 As shown.

[0100] The following describes the other parts of the circulating water tank experimental setup:

[0101] A flow metering unit 6 is provided on the first transmission unit 1 for testing needs in specific experiments.

[0102] Test section 5 is suitable for observing the flow field and the test model. With the help of PIV technology, detailed information such as the flow field around the closed circulating water tank can be captured and measured through test section 5.

[0103] The test section includes an observation frame with a transparent observation window, and the dissolved oxygen measuring device is connected and installed inside the observation frame.

[0104] The test section is equipped with a first test section opening and a second test section opening.

[0105] The observation frame 52 serves to support the observation unit 5 and also supports other measuring devices placed on the observation unit 5. The observation frame 52 can be made of borosilicate glass, and the transparent observation window 53 can be made of plexiglass, which is a material currently available in the technology. Except for the observation unit 5, all other parts are made of stainless steel to ensure the overall stability and safety of the device.

[0106] To control the speed of the centrifugal pump and thus regulate the flow rate and velocity of the solution, the centrifugal pump can also be connected to a frequency converter.

[0107] The dissolved oxygen measuring device 54 uses a dissolved oxygen measuring instrument from the prior art to measure the dissolved oxygen content in the solution within the test section 5.

[0108] A honeycomb unit 271 is installed after the temperature-regulating pipe in the rectifying section 27. Multiple damping nets 272 are installed after the honeycomb unit 271. The honeycomb unit 271 further eliminates the lateral pulsations caused by the large-scale turbulent structure generated by the water tunnel's own circulation. The damping nets 272 divide the large-scale vortices into small-scale vortices, reducing the influence of vortices on the flow field within the observation unit.

[0109] The first tapered tube 24 includes a first tube wall 242. A first transmission port 243 is provided on the first tube wall 242 near the centrifugal pump port 55. The first transmission port 243 is connected to the first observation unit port 51. A second transmission port 241 is provided on the first tube wall 242 away from the first observation unit port 51.

[0110] The first transmission port 243 is smaller than the second transmission port 241.

[0111] The first tube wall 242, the first transmission port 243, and the second transmission port 241 together form the first tapered tube 24. The first transmission port 243 is smaller than the second transmission port 241, causing the first tube wall 242 to tilt from the observation unit 5 side towards the vacuum pump 3 side.

[0112] The second tapered tube 25 includes a second tube wall 252. A third transmission port 251 is provided on the second tube wall 252 near the centrifugal pump port 55, and a fourth transmission port 253 is provided on the second tube wall 252 away from the centrifugal pump port 55. The third transmission port 251 is connected to the centrifugal pump port 55, and the fourth transmission port 253 is connected to the irregular section 26.

[0113] The third transmission port 251 is smaller than the fourth transmission port 253.

[0114] The second pipe wall 252, the third transmission port 251, and the fourth transmission port 253 together form the second tapered pipe 25. The third transmission port 251 is smaller than the fourth transmission port 253, causing the second pipe wall 252 to tilt from the centrifugal pump 4 side to the observation unit 5 side.

[0115] The first transmission unit 1 is provided with a first bending section 11 and a second bending section 12 respectively; the first bending section 11 changes the direction of the solution passing through the second gradient tube 25, thereby reducing the solution pressure and helping to stabilize the pressure of the closed circulating water tank.

[0116] The first curved portion 11 includes a fifth transmission port 111 and a sixth transmission port 112, wherein the fifth transmission port 111 and the sixth transmission port 112 are of the same size;

[0117] The second curved portion 12 includes a seventh transmission port 122 and an eighth transmission port 123. The seventh transmission port 122 and the eighth transmission port 123 are the same size and smaller than the fifth transmission port 111.

[0118] The seventh transmission port 122 is smaller than the radial direction of the first transmission unit 1 near the seventh transmission port 122, and a first inclined portion 121 is provided between the seventh transmission port 122 and the first transmission unit 1 near the seventh transmission port 122.

[0119] The fifth transmission port 111 and the sixth transmission port 112 are the same size, so that the pipe diameter is the same when the solution flows through the first bend 11. The seventh transmission port 122 and the eighth transmission port 123 are the same size and smaller than the fifth transmission port 111, realizing the change of pipe diameter of the first transmission unit 1, thereby increasing the pressure of the fluid flowing through the first inclined section 121 and assisting the operation of the centrifugal pump 4.

[0120] The irregular section 26 includes an irregular tube, which includes a fourth tube wall 261. A fifth tube wall 262 is provided on the outside of the fourth tube wall 261. The end of the fourth tube wall 261 near the test section 5 is connected to the end of the fifth tube wall 262 near the test section 5, and the end of the fourth tube wall 261 away from the test section 5 is not connected to the end of the fifth tube wall 262 away from the test section 5.

[0121] A first port 263 is provided at the end of the fourth pipe wall 261 near the test section 5, a second port 264 is provided at the end of the fourth pipe wall 261 away from the test section 5, and a third port is provided at the end of the fifth pipe wall 262 away from the test section 5. The first port 263 is larger than the second port 264. The second port 264 is connected to the first transmission unit 1, and the third port is connected to the outer surface of the first bend 11.

[0122] In this embodiment, the end of the fourth pipe wall 261 near the test section 5 and the end of the fifth pipe wall 262 near the test section 5 share the first pipe opening 263, and the second pipe opening 264 is smaller than the third pipe opening, so that the diameter of the solution flowing through the shaped pipe is different, increasing the pressure of the solution in the shaped pipe, which is beneficial to the stability of the flow state of the solution in the observation unit 5.

[0123] The second transmission unit 2 is provided with a third gradient tube 22, which includes a third tube wall 223. A ninth transmission port 221 is provided on the third tube wall 223 near the observation unit 5, and a tenth transmission port 222 is provided on the third tube wall 223 near the first transmission unit 1.

[0124] The ninth transmission port 221 is greater than the tenth transmission port 222.

[0125] In this embodiment, the third gradient tube 22 achieves a sudden expansion efficiency density, reducing the impact of the water pump on the flow pattern.

[0126] Another embodiment provided by the present invention, such as Figure 1 As shown, an extension 21 is also provided on the second transmission unit 2 near the third gradient tube 22, and a detachable closure 211 is provided at the end of the extension 21 away from the centrifugal pump 4.

[0127] In this embodiment, the extension 21 can be connected to other test equipment or test apparatus.

[0128] A vacuum pump is also installed on the second transmission unit 2, which is close to the first gradient tube 24.

[0129] A first kneading section 13 is provided on the first transmission unit 1 near the centrifugal pump 4, and a second kneading section 28 is provided on the second transmission unit 2 near the centrifugal pump 4. The first kneading section 13 and the second kneading section 28 buffer the vibration caused by the rotation of the centrifugal pump 4 and reduce the disturbance of mechanical vibration to the flow field inside the observation unit 5.

[0130] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A circulating water tank experimental method for achieving refractive index matching of the flow field, characterized in that, The circulating water tank experimental device includes a vacuum pump (3), a first transmission unit (1), a centrifugal pump (4), and a second transmission unit (2) connected in sequence. The second transmission unit (2) is connected to the vacuum pump (3) to form a closed circulating water tank. The vacuum pump (3) is used to evacuate the closed circulating water tank, and the centrifugal pump (4) is used to drive the solution in the closed circulating water tank to circulate. Among them, a test section (5) is formed on the second transmission unit (2) for placing the structural model to be tested and for projecting a light source, and the solution is a fluid working medium that can make the test section (5) match the solution with the same refractive index; The working fluid is a NaI solution, and the NaI solution has the same refractive index as the test section (5) at a preset temperature and a preset mass concentration. The structure model is used to test its circumferential flow field, and the structure model and the test section are set to the same refractive index. A temperature control unit is provided on the second transmission unit (2). The temperature control unit is used to regulate the temperature of the fluid working medium to fine-tune the refractive index of the fluid working medium so that it matches the refractive index of the test section (5). The second transmission unit (2) includes a rectifier section (27), a first gradient tube (24), a test section (5), a second gradient tube (25), and a shaped section (26) connected in sequence. The rectifier section (27) is located near the centrifugal pump (4), and the shaped section (26) is located near the vacuum pump (3). The first gradient tube (24) is used to enlarge the water flow channel from the test section (5) to reduce the solution pressure in the test section (5). The second gradient tube (25) slows down the water flow into the test section (5); The irregular section (26) is used to transition the incoming flow field within the second tapered tube (25); The rectifying section (27) is used to adjust the flow field; The temperature control unit includes a temperature regulating pipeline installed in the rectifier section (27), and a cold water circulation system and a hot water circulation system installed outside the water tank experimental device. The cold water circulation system and the hot water circulation system form a closed-loop circulating water circuit with the temperature regulating pipeline. The cold water circulation system and the hot water circulation system can regulate the temperature of the water they supply. The experimental methods include: Step 100: Based on the refractive index of the test section and the positive correlation between the refractive index and the solution mass concentration and solution temperature, pre-match a NaI solution with a preset mass concentration and 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 preset temperature. Step 200: Based on the aforementioned correlation, calculate the relationship between the concentration difference between the actual mass concentration and the preset mass concentration and the temperature difference between the actual temperature and the preset temperature; Step 300: The vacuum pump draws a vacuum to form a vacuum state in the closed circulating water tank, and a preset amount of NaI solution is introduced into the tank. At the same time, the centrifugal pump is started to drive the NaI solution in the closed circulating water tank to circulate. Step 400: Monitor the mass concentration and temperature of the NaI solution in the closed circulating water tank in real time; When the temperature is higher than the preset temperature, the cold water circulation system is activated to adjust the NaI solution to the preset temperature; when the temperature is lower than the preset temperature, the hot water circulation system is activated to adjust the NaI solution to the preset temperature. When the mass concentration is lower than the preset mass concentration, NaI is added to the closed circulating water tank until it reaches the preset mass concentration, or the first compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula, and the hot water circulation system is activated to adjust the NaI solution to the first compensation temperature. When the mass concentration is higher than the preset mass concentration, a second compensation temperature is calculated based on the difference between the current mass concentration and the preset mass concentration, and the relationship between the difference, so that the refractive index of the NaI solution can be matched to the refractive index of the test section. The cold water circulation system is then activated to adjust the NaI solution to the second compensation temperature, so as to balance the refractive indices of the test section and the NaI solution to make them the same. Step 500: Until a stable NaI solution circulation flow is formed in the closed circulating water tank, a stable simulation environment is provided for the application simulation test of the structural model.

2. The circulating water tank experimental method for achieving flow field refractive index matching according to claim 1, characterized in that, The test segment (5) is one segment of the second transmission unit (2). The test segment (5) is transparent and is also used to observe the structure model inside it during testing.

3. The circulating water tank experimental method for achieving flow field refractive index matching according to claim 2, characterized in that, The test section (5) is a high borosilicate hollow glass column.

4. A circulating water tank experimental method for achieving refractive index matching of the flow field, characterized in that, The circulating water tank experimental device includes a vacuum pump (3), a first transmission unit (1), a centrifugal pump (4), and a second transmission unit (2) connected in sequence. The second transmission unit (2) is connected to the vacuum pump (3) to form a closed circulating water tank. The vacuum pump (3) is used to evacuate the closed circulating water tank, and the centrifugal pump (4) is used to drive the solution in the closed circulating water tank to circulate. Among them, a test section (5) is formed on the second transmission unit (2) for placing the structural model to be tested and for projecting a light source, and the solution is a fluid working medium that can make the test section (5) match the solution with the same refractive index; The working fluid is a NaI solution, and the NaI solution has the same refractive index as the test section (5) at a preset temperature and a preset mass concentration. The structure model is used to test its circumferential flow field, and the structure model and the test section are set to the same refractive index. A temperature control unit is provided on the second transmission unit (2). The temperature control unit is used to regulate the temperature of the fluid working medium to fine-tune the refractive index of the fluid working medium so that it matches the refractive index of the test section (5). The second transmission unit (2) includes a rectifier section (27), a first gradient tube (24), a test section (5), a second gradient tube (25), and a shaped section (26) connected in sequence. The rectifier section (27) is located near the centrifugal pump (4), and the shaped section (26) is located near the vacuum pump (3). The first gradient tube (24) is used to enlarge the water flow channel from the test section (5) to reduce the solution pressure in the test section (5). The second gradient tube (25) slows down the water flow into the test section (5); The irregular section (26) is used to transition the incoming flow field within the second tapered tube (25); The rectifying section (27) is used to adjust the flow field; The temperature control unit includes a temperature regulating pipe installed in the rectifier section (27), and a chiller and a hot water heater installed outside the water tank experimental device. The chiller and the hot water heater are connected to an external constant temperature circulation pipe. The external constant temperature circulation pipe is connected to the temperature regulating pipe to form a constant temperature water circulation that can always maintain the set temperature. The set temperature is achieved by the coordinated control of the chiller and the hot water heater. The experimental methods include: Step 100: Based on the refractive index of the test section and the positive correlation between the refractive index and the solution mass concentration and solution temperature, pre-match a NaI solution with a preset mass concentration and 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 preset temperature. Step 200: Based on the aforementioned correlation, calculate the relationship between the concentration difference between the actual mass concentration and the preset mass concentration and the temperature difference between the actual temperature and the preset temperature; Step 300: The vacuum pump draws a vacuum to form a vacuum state in the closed circulating water tank, and a preset amount of NaI solution is introduced into the tank. At the same time, the centrifugal pump is started to drive the NaI solution in the closed circulating water tank to circulate. Step 400: The chiller and the water heater form a constant temperature water circulation at a preset temperature in the temperature control pipeline to maintain the preset temperature of the NaI solution in the closed circulating water tank. Step 500: Real-time monitoring of the mass concentration of the NaI solution in the closed circulating water tank. When the mass concentration is lower than the preset mass concentration, NaI is added to the closed circulating water tank until it reaches the preset mass concentration, or a third compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula, and the chiller and the hot water machine are started 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, the fourth compensation temperature that can match the refractive index of the NaI solution to the refractive index of the test section is calculated based on the difference between the current mass concentration and the preset mass concentration and the difference relationship formula. The chiller and the hot water machine are started to adjust the temperature in the constant temperature water circulation to the fourth compensation temperature in order to balance the refractive indices of the test section and the NaI solution to make them the same. Step 600: Until a stable NaI solution circulation flow is formed in the closed circulating water tank, a stable simulation environment is provided for the application simulation test of the structural model.

5. The circulating water tank experimental method for achieving flow field refractive index matching according to claim 4, characterized in that, The test segment (5) is one segment of the second transmission unit (2). The test segment (5) is transparent and is also used to observe the structure model inside it during testing.

6. The circulating water tank experimental method for achieving flow field refractive index matching according to claim 5, characterized in that, The test section (5) is a high borosilicate hollow glass column.

Images