A confined space fluid resistance precision testing system and method

Abstract

The present application relates to the technical fields of experimental fluid mechanics and precision testing instrument, and discloses a kind of fluid resistance precision test system and method in confined space, including thermostatic container component, including coaxial setting inner measuring tube and outer sheath pipe, outer sheath pipe bottom is fixed in positioning hoop.This application uses double-layer coaxial sleeve pipe to match bottom positioning hoop structure, constructs thermostatic cavity with mechanical centering datum as one and coaxial, guarantee the absolute perpendicularity of long-stroke measurement, with the help of dynamic pressure suspension guiding unit and double-line parallel traction mechanism, realize center guiding wire and traction component physical isolation, eliminate cable winding and friction noise, simultaneously through top detachable positioning support and the spiral quick-release hook cooperation of dynamic pressure suspension guiding unit, without cutting heavy binding traction line, can quickly replace test sphere under the premise of reserving system centering datum, so as to greatly improve the efficiency of multi-working condition comparison experiment.

Description

Technical Field

[0001] This invention relates to the field of experimental fluid mechanics and precision testing instruments, and in particular to a precision testing system and method for fluid resistance in confined spaces. Background Technology

[0002] Precision testing of fluid resistance in confined spaces is a key technology for fundamental research in fluid mechanics, microscale fluid engineering, and the development of special fluid materials. In particular, it is crucial for testing the resistance characteristics of Newtonian fluids, power-law fluids, and yield-pseudoplastic fluids within extremely confined annular gaps. This requires stringent standards for the alignment accuracy, isothermal stability, force measurement signal-to-noise ratio, and ease of operation of the experimental setup.

[0003] Traditional confined space fluid resistance testing devices mostly use a single tube cavity as the test carrier, placing the sphere to be tested directly inside the tube. The sphere is pulled along the axial direction of the tube by a single pull wire or rigid rod. A simple drive mechanism and force measuring components are used to realize motion traction and resistance acquisition. During the test, the sphere is directly driven to move in a straight line in the fluid inside the tube, and the force sensor collects the force signal to complete the fluid resistance test.

[0004] However, in actual use, traditional testing devices are prone to problems such as eccentricity and friction against the wall when the sphere moves within the cavity. Furthermore, they are prone to shaking and cable entanglement during the pulling process. In addition, ambient temperature and heat generated by motion can easily cause fluid temperature fluctuations, which in turn can change the fluid viscosity characteristics. At the same time, interference factors such as mechanical friction and flow field disturbances cannot be effectively eliminated, making the force measurement signal prone to distortion. This leads to a significant decrease in the accuracy of the test data, making it difficult to adapt to the precision testing requirements of Newtonian and non-Newtonian fluids, and thus failing to meet the requirements of high-precision fluid resistance testing. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a precision testing system and method for fluid resistance in confined spaces.

[0006] This invention provides a precision testing system for fluid resistance in confined spaces, comprising:

[0007] A thermostatic container assembly includes an inner measuring tube and an outer sheath tube arranged coaxially, with the bottom of the outer sheath tube fixed inside a positioning clamp.

[0008] The center guide assembly includes a guide wire arranged along the axis of the inner measuring tube, a self-centering base fixed to the bottom of the inner measuring tube, and a detachable positioning bracket fixed to the top of the inner measuring tube. The two ends of the guide wire are respectively fixed to the self-centering base and the detachable positioning bracket.

[0009] The test sphere assembly includes a test sphere with a through cavity in the center, a self-lubricating bushing inside the cavity, and the self-lubricating bushing being slidably sleeved on the guide wire;

[0010] A dynamic pressure suspension guide unit is disposed above the test sphere. The dynamic pressure suspension guide unit includes a dynamic pressure self-lubricating sleeve slidably sleeved on the guide wire. A plurality of evenly distributed support winglets are installed on the outer periphery of the dynamic pressure self-lubricating sleeve. The number of support winglets is even and they are radially distributed. A counterweight structure is installed at the end of the support winglets away from the dynamic pressure self-lubricating sleeve. Symmetrical hanging points are installed on any two radially symmetrical counterweight structures. The two symmetrical hanging points are connected to the test sphere through connectors.

[0011] The precision drive and force measurement assembly includes a linear drive module, a force sensor, and a dual-line traction mechanism mounted on a gantry. The linear drive module adopts a ball screw slide structure. The force sensor is mounted on the moving part of the linear drive module and is connected to the dynamic pressure suspension guide unit through the dual-line traction mechanism.

[0012] Furthermore, the inner measuring tube and the outer sheath tube are connected at both ends by a sealing centering flange to form a sealed constant temperature cavity. The sealing centering flange is provided with sealing grooves that respectively seal and cooperate with the outer wall of the inner measuring tube and the inner wall of the outer sheath tube.

[0013] Furthermore, the dual-line traction mechanism includes a balance crossbeam connected to the force sensor and two parallel traction lines extending vertically downwards from both ends of the balance crossbeam. The ends of the two traction lines away from the balance crossbeam are respectively connected to two symmetrical hanging points of the dynamic pressure suspension guide unit.

[0014] Furthermore, the spokes of the detachable positioning bracket are provided with a plurality of opening slots for the radial entry and exit of the two traction lines, and the center of the detachable positioning bracket is provided with a quick-release clamp, which is used to lock the guide wire.

[0015] Furthermore, the outer edge of the self-centering base is clearance-fitted with the inner wall of the inner measuring tube, and the bottom end of the guide wire is fixed to the center of the self-centering base.

[0016] Furthermore, the outer surface of the test sphere is provided with two symmetrically arranged traction interfaces. The two traction interfaces are respectively arranged with two symmetrical hanging points and two traction lines. The two traction lines are respectively connected to the connectors embedded in the two traction interfaces. The two traction interfaces are located in the range below the maximum sphere outline and above the lowest point of the sphere. The traction interfaces are filled with epoxy resin composite material. The maximum radial dimension of the dynamic pressure suspension guide unit is smaller than the diameter of the test sphere.

[0017] A test method for a precision testing system for fluid resistance in confined spaces includes the following steps:

[0018] In non-immersion conditions, the hydrodynamic self-lubricating sleeve is simply fitted onto the guide wire and connected to the traction line. The linear drive module drives the hydrodynamic self-lubricating sleeve to run along the guide wire at a preset speed sequence. The average tension value at different speeds is recorded by the force sensor to obtain the friction damping characteristic curve of the mechanical transmission system.

[0019] After completing the calibration of the friction damping characteristic curve, the test ball is inserted into the guide wire and hung on the symmetrical hanging point of the counterweight structure through the connector. The linear drive module is driven to lower the test ball so that it is completely immersed in the fluid and lowered to the predetermined measurement depth starting position and left to stand still. After the fluid disturbance disappears and the force sensor reading stabilizes, the static reading is recorded to obtain the zero-point buoyancy reference.

[0020] Based on the zero-point buoyancy benchmark calibration, the test sphere is pulled at a preset constant speed by the linear drive module to rise uniformly in the fluid, and the force sensor collects the total tension signal in real time during the motion process with a high sampling rate.

[0021] Based on the obtained friction damping characteristic curve of the mechanical transmission system and the zero-point buoyancy reference, the collected total tension signal is differentially processed to obtain the pure fluid dynamic resistance value after deducting the effects of mechanical friction and buoyancy.

[0022] Time-domain statistical analysis was performed on the pure fluid dynamics resistance value. The arithmetic mean was extracted as the steady-state viscous resistance component, and the standard deviation was extracted as the fluid elastic fluctuation intensity.

[0023] Constructing a dimensionless parameter fluctuation intensity factor Set the volatility intensity factor threshold range The flow field state is divided into domains:

[0024] when When the flow field is determined to be dominated by laminar viscosity, only the steady-state viscous drag component is output as the final hydrodynamic drag value.

[0025] when When the flow field is determined to be in the viscoelastic coupling transition region, the steady-state viscous drag component and the fluid elastic fluctuation intensity are dynamically decoupled and coupled to obtain the final fluid dynamic drag value and output it.

[0026] when When wall slip or turbulent transition occurs in the flow field, a slip velocity correction term is introduced to compensate for the effective shear rate. The compensation calculation result is multiplied with the steady-state viscous drag component to obtain the final hydrodynamic drag value and output it.

[0027] Compared with the prior art, the technical solution provided by the embodiments of the present invention has the following advantages: The present invention adopts a double-layer coaxial sleeve with a bottom positioning hoop structure to integrate the constant temperature chamber construction and the mechanical centering reference into one and coaxial, ensuring absolute perpendicularity in long-stroke measurement and effectively eliminating measurement errors caused by eccentricity. Subsequently, the dynamic pressure suspension guide unit, in conjunction with the double-line parallel traction mechanism, achieves physical isolation between the central guide wire and the traction component in space, eliminating cable entanglement and friction noise, and improving the signal-to-noise ratio of small force measurement. At the same time, through the quick cooperation of the top detachable positioning bracket and the spiral quick-release hook on the dynamic pressure suspension guide unit, the experimenter can quickly change the test ball without cutting or retying the traction line while keeping the system centering reference unchanged. This effectively avoids the measurement data distortion problem caused by the hand-throwing test method and similar test methods such as single-line traction, thereby greatly improving the efficiency of multi-condition comparison experiments. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2 This is a schematic cross-sectional view of the overall structure provided by the present invention;

[0030] Figure 3 Provided by the present invention Figure 2 Enlarged view of point A in the middle;

[0031] Figure 4 A schematic diagram of the detachable positioning bracket structure provided by the present invention;

[0032] Figure 5 This is a schematic diagram of the dynamic pressure suspension guide unit structure provided by the present invention;

[0033] Figure 6 This is a schematic diagram of the self-centering base structure provided by the present invention;

[0034] Figure 7 This is a schematic diagram of a half-section of the test sphere assembly provided by the present invention;

[0035] Figure 8The data processing algorithm flowchart provided for this invention;

[0036] Figure 9 Decoupling diagram of the resistance signal algorithm provided by this invention;

[0037] Figure 10 A line graph comparing experimental data provided for this invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Gantry frame; 10. Test sphere; 11. Positioning clamp; 12. Adjustable foot; 13. Dynamic pressure suspension guide unit; 131. Counterweight structure; 132. Dynamic pressure self-lubricating sleeve; 133. Support wing; 134. Symmetrical hanging points; 14. Self-lubricating bushing; 15. Traction line;

[0040] 2. Linear drive module;

[0041] 3. Force sensor; 31. Balance crossbeam;

[0042] 4. Inner measuring tube; 41. Outer sheath tube; 42. Sealing centering flange;

[0043] 5. Detachable positioning bracket; 51. Opening slot; 52. Quick-release chuck;

[0044] 6. Guide wire;

[0045] 7. Self-centering base. Detailed Implementation

[0046] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] The present invention will be described below through several specific embodiments. To keep the following description of the embodiments clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present invention appears in more than one drawing, the component may be represented by the same reference numerals in each drawing.

[0049] like Figures 1-8 As shown, a precision testing system for fluid resistance in confined spaces includes:

[0050] The thermostatic container assembly includes an inner measuring tube 4 and an outer sheath tube 41 arranged coaxially, with the bottom of the outer sheath tube 41 fixed inside the positioning clamp 11;

[0051] The center guide assembly includes a guide wire 6 arranged along the axis of the inner measuring tube 4, a self-centering base 7 fixed to the bottom of the inner measuring tube 4, and a detachable positioning bracket 5 fixed to the top of the inner measuring tube 4. The two ends of the guide wire 6 are respectively fixed to the self-centering base 7 and the detachable positioning bracket 5.

[0052] The test sphere assembly includes a test sphere 10 with a through cavity in the center, a self-lubricating bushing 14 inside the cavity, and the self-lubricating bushing 14 is slidably sleeved on the guide wire 6.

[0053] The dynamic pressure suspension guide unit 13 is located above the test sphere 10. The dynamic pressure suspension guide unit 13 includes a dynamic pressure self-lubricating sleeve 132 that is slidably sleeved on the guide wire 6. Several evenly distributed support wing pieces 133 are installed on the outer periphery of the dynamic pressure self-lubricating sleeve 132. The number of support wing pieces 133 is even and they are radially distributed. A counterweight structure 131 is installed at the end of the support wing piece 133 away from the dynamic pressure self-lubricating sleeve 132. Symmetrical hanging points 134 are installed on any two radially symmetrical counterweight structures 131. The two symmetrical hanging points 134 are connected to the test sphere 10 through connectors.

[0054] The precision drive and force measurement assembly includes a linear drive module 2 mounted on the gantry 1, a force sensor 3, and a dual-line traction mechanism. The linear drive module 2 adopts a ball screw slide structure. The force sensor 3 is mounted on the moving part of the linear drive module 2 and is connected to the dynamic pressure suspension guide unit 13 through the dual-line traction mechanism. The constant temperature container assembly forms a constant temperature test chamber through the coaxially arranged inner measuring tube 4 and outer sheath tube 41. The outer sheath tube 41 is fixed and positioned by the positioning clamp 11, thereby ensuring a constant temperature test environment and coaxiality of the pipeline without deviation. The center guide assembly... Under the dual fixation of the bottom self-centering base 7 and the top detachable positioning bracket 5, the guide wire 6 forms a guiding reference along the axis of the inner measuring tube 4, providing an eccentric motion path for the test ball 10. The test ball 10 is smoothly fitted onto the guide wire 6 through the internal self-lubricating bushing 14. When the self-lubricating bushing 14 slides along the guide wire 6, the lubricant inside it can automatically precipitate and form a smooth lubricating film on the contact surface between the self-lubricating bushing 14 and the guide wire 6, effectively reducing the frictional resistance between the two and preventing wear of the guide wire 6, ensuring that the test ball 10 moves smoothly along the guide wire 6. The guide wire 6 moves smoothly, avoiding movement jamming and wear. The dynamic pressure suspension guide unit 13, located above the test ball 10, slides against the guide wire 6 with the help of the dynamic pressure self-lubricating sleeve 132. The radially distributed support wings 133 and the counterweight structure 131 ensure stable operation. The symmetrical hanging points 134 on the counterweight structure 131 drive the test ball 10 to move synchronously through the connector, eliminating traction swaying and cable entanglement. In the precision drive and force measurement components, the ball screw slide-type linear drive module 2 on the gantry 1 provides stable and uniform power, with a power sensor. 3. The dual-line traction mechanism operates smoothly. The dual-line traction mechanism is connected to the symmetrical hanging point 134 of the dynamic pressure suspension guide unit 13, which pulls the dynamic pressure suspension guide unit 13 and the test ball 10 to move in a directional and uniform speed along the guide wire 6. During the test, the force sensor 3 accurately collects the resistance signal of the test ball 10 in the fluid in real time. After removing interference such as mechanical friction and equipment disturbance, it outputs accurate fluid resistance data, which solves the problems of eccentric adhesion, friction interference and flow field disturbance in traditional tests, thus adapting to the precise resistance test requirements of various Newtonian and non-Newtonian fluids.

[0055] Furthermore, such as Figures 1-8 As shown, the positioning hoop 11 is welded to the bottom of the gantry frame 1. Adjustable feet 12 are provided at the four corners of the bottom of the gantry frame 1. The positioning hoop 11 is welded to the bottom of the gantry frame 1 to fix the constant temperature container assembly to ensure coaxial alignment, while the four corner adjustable feet 12 are used to adjust the level of the gantry frame 1, thereby ensuring the vertical accuracy and stable operation of the test system.

[0056] Furthermore, such as Figures 1-8As shown, the inner measuring tube 4 and the outer sheath tube 41 are connected at both ends by a sealing centering flange 42 to form a sealed constant temperature cavity. The sealing centering flange 42 has sealing grooves that respectively seal and cooperate with the outer wall of the inner measuring tube 4 and the inner wall of the outer sheath tube 41. The connection between the inner measuring tube 4 and the outer sheath tube 41 at both ends by the sealing centering flange 42 can not only achieve a sealed fit between the inner and outer tubes by relying on the sealing grooves, thus building a solid and sealed constant temperature cavity to prevent media leakage, but also forcefully limit the coaxiality of the inner and outer tubes, ensuring the alignment accuracy of the pipeline, providing a stable constant temperature environment for fluid resistance testing, thereby avoiding eccentricity and leakage from affecting the measurement results.

[0057] Furthermore, such as Figures 1-8 As shown, the dual-line traction mechanism includes a balance crossbeam 31 connected to the force sensor 3 and two parallel traction lines 15 extending vertically downwards from both ends of the balance crossbeam 31. The ends of the two traction lines 15 furthest from the balance crossbeam 31 are respectively connected to two symmetrical hanging points 134 of the dynamic pressure suspension guide unit 13. Through the balance crossbeam 31 connected to the force sensor 3, and the traction lines 15 extending vertically downwards from both ends, the dual-line traction mechanism connects the symmetrical hanging points 134 of the dynamic pressure suspension guide unit 13, enabling uniform and symmetrical transmission of traction force. This avoids the problems of skewness and jamming caused by unilateral traction, thereby ensuring that the dynamic pressure suspension guide unit 13 and the test ball 10 rise and fall smoothly and vertically along the guide wire 6, preventing swaying, deviation, or even cable entanglement during traction. At the same time, it makes the force measurement of the force sensor 3 more accurate, effectively eliminating the force measurement error caused by eccentric force, thus ensuring the authenticity and reliability of the collected fluid resistance data, and further improving the stability and measurement accuracy of fluid resistance testing in confined spaces.

[0058] Furthermore, such as Figures 1-8 As shown, the spokes of the detachable positioning bracket 5 are provided with several slots 51 for the radial entry and exit of the two traction wires 15, and the center of the detachable positioning bracket 5 is provided with a quick-release chuck 52. The quick-release chuck 52 is used to lock the guide wire 6. The spokes of the detachable positioning bracket 5 are provided with slots 51 for the radial entry and exit of the two traction wires 15. The center quick-release chuck 52 is used to quickly lock and release the guide wire 6. The bracket and the ball can be quickly disassembled and replaced without cutting the traction wires 15 or damaging the guide reference, thereby improving the testing efficiency and ensuring the centering accuracy.

[0059] Furthermore, such as Figures 1-8 As shown, the outer edge of the self-centering base 7 is fitted with the inner wall of the inner measuring tube 4 with a clearance, and the bottom end of the guide wire 6 is fixed to the center of the self-centering base 7. The clearance fit between the self-centering base 7 and the inner wall of the inner measuring tube 4 can achieve centering and positioning, ensuring that the guide wire 6 is always in the center position, effectively preventing the guide wire 6 from shaking or deviating, ensuring the stability and reliability of the measurement process, and providing stable support and guidance for the inner measuring components, thereby improving the overall stability and measurement accuracy of the device.

[0060] Furthermore, such as Figures 1-8 As shown, the outer surface of the test sphere 10 is provided with traction interfaces. Two traction interfaces are respectively set with two symmetrical hanging points 134 and two traction lines 15. The two traction lines 15 are respectively connected to the connectors embedded inside the two traction interfaces. The two traction interfaces are located in the area below the maximum spherical contour line and above the lowest point of the sphere. The traction interfaces are filled with epoxy resin composite material. The maximum radial dimension of the dynamic pressure suspension guide unit 13 is smaller than the diameter of the test sphere 10. The two symmetrical traction interfaces on the outer surface of the test sphere 10, corresponding to the symmetrical hanging points 134 and traction lines 15, ensure symmetrical and balanced traction force, prevent swaying or deflection of the sphere during testing, ensure stable motion posture, and position the two traction interfaces below the maximum contour line and the lowest point of the test sphere 10. Within the range above the point, the internal guide wire 6 chamber of the sphere can be avoided, eliminating structural interference, ensuring a reasonable traction force application position, and guaranteeing test accuracy. At the same time, after the traction line 15 is connected to the connector embedded inside the traction interface, epoxy resin composite material is filled into the traction interface through a caulking process. Combined with a polishing process, the traction interface position of the test sphere 10 and the sphere surface achieve a smooth and seamless transition. This not only strengthens the connection strength and sealing stability of the internally embedded connector, but also eliminates structural defects such as bulges and grooves on the sphere surface, avoiding damage to the smoothness of the sphere surface. The maximum radial dimension of the dynamic pressure suspension guide unit 13 is smaller than the diameter of the test sphere 10, which can ensure that the test sphere 10 is subjected to uniform force and has a smooth flow field during operation, avoiding disturbances or jamming at the traction interface, thereby ensuring a stable test process and accurate data.

[0061] like Figures 1-8 As shown, a test method for a precision testing system for fluid resistance in confined spaces includes the following steps:

[0062] Step 1: Under non-immersion conditions, only the hydrodynamic self-lubricating sleeve 132 is fitted onto the guide wire 6 and connected to the traction line 15. The linear drive module 2 drives the hydrodynamic self-lubricating sleeve 132 to run along the guide wire 6 at a preset speed sequence. The average tension value at different speeds is recorded by the force sensor 3 to obtain the friction damping characteristic curve of the mechanical transmission system.

[0063] 1) Environment Setup: Start the external circulation constant temperature water bath system and set the target experimental temperature (e.g., ...). Slowly inject the non-Newtonian fluid to be tested into the inner measuring tube 4, and let it stand for 20-30 minutes until the fluid temperature reaches thermal equilibrium and the internal bubbles completely escape.

[0064] 2) Benchmark establishment: Use a laser plumb line to check the verticality of the gantry frame 1, install the guide wire 6, and apply preload through the top adjusting nut to ensure that the guide wire 6 is taut throughout its entire length, thus establishing an absolutely vertical guide benchmark.

[0065] 3) No-load mounting: Only the hydrodynamic self-lubricating sleeve 132 (without mounting the test ball 10) is placed on the guide wire 6, and it is connected to the force sensor 3 through the double-line traction mechanism to ensure that the traction line 15 is in a straight state and does not contact the guide wire 6.

[0066] 4) Velocity sequence scanning: Using the host computer control software, a set of traction velocity sequences covering the experimental conditions is set. ;

[0067] 5) Friction reference acquisition: The linear drive module 2 sequentially lifts the dynamic pressure suspension guide unit 13 at each set speed. During the stable operation segment of each speed, the force sensor 3 acquires the average tension at a high sampling rate (not less than 1000 Hz).

[0068] 6) Curve fitting: Record the mechanical resistance value corresponding to each speed point, and use the polynomial fitting method to construct the speed-mechanical friction characteristic curve as the benchmark for subsequent data correction.

[0069] Step 2: After completing the calibration of the friction damping characteristic curve, the test ball 10 is fitted into the guide wire 6 and hung on the symmetrical hanging point 134 of the counterweight structure 131 through the connector. The linear drive module 2 is driven to lower the test ball 10 so that it is completely immersed in the fluid and lowered to the predetermined measurement depth starting position and left to stand. After the fluid disturbance disappears and the reading of the force sensor 3 stabilizes, the static reading is recorded to obtain the zero-point buoyancy reference.

[0070] 1) Pretreatment of the sphere: Select the test sphere 10 to be tested, check the surface smoothness, and use an ethanol or surfactant solution compatible with the test fluid to completely wet the surface of the sphere to prevent microbubbles from adsorbing on the surface when entering the water, which would cause buoyancy error.

[0071] 2) Dual-line mounting: Move the linear drive module 2 down to the replacement position, use the U-shaped opening slot 51 of the top bracket to move the cable of the dual-line traction mechanism into the inner tube, put the test ball into the guide wire, and tie the ends of the traction line 15 to the symmetrical hanging points 134 respectively to complete the mechanical connection between the dual-line traction and the ball.

[0072] 3) Immersion and positioning: The control module descends slowly, completely immersing the test sphere 10 in the fluid, and descends to the preset measurement starting depth, usually more than 200mm from the bottom, to eliminate the bottom effect;

[0073] 4) Static stabilization: Keep the sphere stationary for 2-5 minutes, waiting for the disturbance ripples on the fluid surface to completely disappear, while observing the fluctuation of the force sensor 3 reading;

[0074] 5) Zero-point locking: The reading of the load sensor 3 stabilizes at... When the system is within the specified range, record the current static force value; this value will serve as the system's zero-point buoyancy reference. :

[0075] ,

[0076] in For the weight of the ball, For guiding unit weight, This is the total static buoyancy force experienced by the sphere and the guide unit.

[0077] Step 3: After completing the zero-point buoyancy benchmark calibration, the linear drive module 2 pulls the test ball 10 at a preset constant speed to rise uniformly in the fluid, and the force sensor 3 collects the total tension signal in real time during the motion process at a high sampling rate.

[0078] 1) Motion parameter setting: Set the constant strain rate (traction speed) for a single experiment in the control software. ) and effective measurement stroke, set the trigger mode and data recording path of force sensor 3;

[0079] 2) Flow field pre-shear: For thixotropic fluids, a high-speed pre-shear operation is performed first to eliminate the fluid's memory effect, followed by a specified time of settling to restore the initial structure;

[0080] 3) Constant speed traction: Start the linear drive module 2 to drive the test ball 10 to rise vertically along the guide wire 6. The system goes through three processes: "acceleration section - constant speed section - deceleration section".

[0081] 4) Full-range data recording: Force sensor 3 records the instantaneous tension signal throughout the entire process in real time. The data is mainly extracted from the uniform velocity segment, which reflects the actual resistance of the fluid under a steady shear field.

[0082] Step 4: Based on the obtained friction damping characteristic curve of the mechanical transmission system and the zero-point buoyancy reference, perform differential processing on the collected total tension signal to obtain the pure fluid dynamic resistance value after deducting the effects of mechanical friction and buoyancy.

[0083] After the experiment, the system automatically retrieves the baseline data from steps one and two and uses the difference formula to calculate the pure fluid dynamic resistance. The original waveform file is saved for subsequent dynamic decoupling analysis, and the formula is as follows:

[0084] .

[0085] Step 5: Perform time-domain statistical analysis on the pure fluid dynamic resistance value, extract the arithmetic mean as the steady-state viscous resistance component, and extract the standard deviation as the fluid elastic fluctuation intensity;

[0086] 1) The physical model is constructed under constant strain rate (uniform speed) traction conditions, and the instantaneous total tensile force signal collected by force sensor 3 is used. It is not a constant value, but rather exhibits dynamic fluctuations based on the steady-state mean. Based on the principle of linear superposition, we decompose the instantaneous total tensile force into three independent components, as shown in the following formula:

[0087] ,

[0088] in, The instantaneous total tensile force collected by the sensor; The steady-state viscous drag component, characterizing the shear viscosity contribution of the fluid, is obtained through the arithmetic mean of the signal; The dynamic viscoelastic wave component characterizes the rheological dynamic disturbance of a non-Newtonian fluid caused by elastic stretching or wall slip, and is the equivalent drag correction value calculated based on variance (or standard deviation). The system's background noise component represents mechanical vibration and electromagnetic interference, which is eliminated through frequency domain filtering.

[0089] 2) For the initial extraction Deep decoupling is achieved using multi-order statistical moment analysis, with the specific steps as follows:

[0090] ①Signal time-domain multi-order decomposition

[0091] Time-domain statistical analysis was performed on the force signals acquired at high frequencies, and the arithmetic mean of the signals was extracted as the steady-state resistance. Preliminary estimate; extract the variance or standard deviation (second central moment) of the signal. To characterize the elastic wave intensity of the fluid;

[0092] ② Fluctuation energy ratio and flow regime discrimination

[0093] Constructing a dimensionless parameter fluctuation intensity factor This is used to quantify the degree to which a fluid transforms from laminar shear deformation to turbulent or elastic tensile deformation, and the formula is as follows:

[0094] ,

[0095] This factor reflects the proportion of dynamic fluctuation energy in macroscopic resistance. This algorithm introduces a flow-adaptive boundary determination mechanism and sets a threshold range. The flow field state is divided into domains as follows:

[0096] Laminar viscosity-dominated region The fluid exhibits Newtonian-like fluid characteristics with minimal fluctuations. In this case, elastic effects can be ignored, and the output can be directly determined. As the ultimate resistance;

[0097] Viscoelastic coupling transition region The fluid exhibits significant viscoelastic characteristics, and the difference in normal stress leads to an additional drag effect.

[0098] Slip / turbulence transition zone When severe wall slip or turbulence occurs in the flow field, a slip velocity correction term needs to be introduced to compensate for the effective shear rate.

[0099] ③ Elastic correction for non-Newtonian fluids

[0100] For the viscoelastic coupling transition region, a method based on the Weissenberg number is introduced. The elastic correction function eliminates the additional drag effect caused by the normal stress difference in a confined space for polymer fluids, and the formula is as follows:

[0101] ,

[0102] In the formula, The elastic-resistance conversion efficiency coefficient represents the proportion of wave energy converted into macroscopic resistance correction. It is a nonlinear decay exponent, reflecting the fluid's sensitivity to dynamic disturbances. and All of these are rheological characteristic constants, obtained through fitting experiments using standard viscoelastic fluid calibration.

[0103] ④ Effective shear rate compensation

[0104] First, two core values ​​are obtained from the collected signals during the constant velocity segment: apparent traction speed. That is, the operating speed and steady-state viscous drag component of the linear drive module set in the experiment. To determine the degree of slippage, it is necessary to first calculate the characteristic wall shear stress on the surface of the test sphere 10. The formula is as follows:

[0105] ,

[0106] To test the effective shear area of ​​sphere 10 within a confined annulus;

[0107] By introducing a wall slip model, the slip velocity loss due to boundary layer failure is calculated, and the slip velocity is obtained. The formula is as follows:

[0108] ,

[0109] The slip coefficient, These are slip exponents, all of which are pre-calibrated physical property constants for non-Newtonian fluids;

[0110] To obtain an effective traction speed Subtracting slip loss from the set apparent velocity, the true relative shear velocity inside the fluid is obtained by the following formula:

[0111] ,

[0112] Output final resistance The formula is as follows:

[0113] ,

[0114] n The fluidity index;

[0115] Using the calibrated correction factor, from the average resistance By eliminating spurious drag increments caused by elastic turbulence or resonance in the test system, a pure drag value that is only related to the intrinsic rheological properties of the fluid is obtained.

[0116] Furthermore, after completing a set of tests, the method of replacing spheres with different diameters includes the following steps:

[0117] Step 1: Loosen the quick-release chuck 52 at the center of the detachable positioning bracket 5, and hold the top of the guide screw 6 to prevent retraction;

[0118] Step 2: Move the two parallel traction lines 15 of the double-line traction mechanism laterally through the U-shaped opening slot 51 on the bracket spokes;

[0119] Step 3: Remove the detachable positioning bracket 5 and raise the dynamic pressure suspension guide unit 13 above the liquid surface;

[0120] Step 4: Unscrew the old ball from the hanging point and replace it with a new ball;

[0121] Step 5: Perform the above operations in reverse order to reset. This process does not require cutting the traction wire 15 and keeps the guide wire 6 reference unchanged.

[0122] Repeat steps two through four above for the newly replaced sphere to obtain fluid resistance data under multiple operating conditions.

[0123] Example 2

[0124] Based on Example 1, a field demonstration was conducted.

[0125] In a test pipe section with an inner diameter of 50 mm, a series of comparative tests were conducted using the traditional unguided ball-dropping sedimentation method and the present invention. The diameter of the test spheres 10 ranged from 5 mm to 45 mm (corresponding to a blockage ratio λ ranging from 0.1 to 0.9). The experimental data showed the following three significant stage characteristics:

[0126] Within the range of 10 test spheres with a diameter λ ≤ 0.3, the flow channel space is ample, the wall effect is weak, and the traditional ball-throwing method can maintain relatively stable center settlement without significant lateral displacement. The fluid viscous resistance data measured by the two systems are highly consistent, proving the accuracy of the benchmark measurement of the system of this invention under normal operating conditions.

[0127] As the diameter of the test sphere increases by 0.3 < λ ≤ 0.6, the asymmetric compression effect of the confined flow field is sharply enhanced. Due to the lack of mechanical constraints, the traditional sphere throwing method causes the sphere to deviate from the tube center due to disturbances such as the fluid Magnus force. This results in the measured value being significantly higher than the theoretical fluid resistance, and the discrete error of a single test is drastically amplified. However, the system of this invention relies on the strict physical constraint of the central guide wire to ensure that the sphere is absolutely coaxial and accurately extracts the pure fluid resistance in this range.

[0128] When the diameter of the test sphere exceeds 30mm, the traditional ball-throwing method causes the sphere to directly collide with one side of the pipe wall due to the extremely high obstruction ratio, making it impossible to obtain effective sinking data. In contrast, the system of this invention, with its powerful mechanical centering reference, breaks through the traditional testing limit and successfully measures the drag exponential increase curves at 35mm, 40mm, and even the extreme case of 45mm (λ=0.9), greatly expanding the testing range of fluid dynamics in confined spaces.

[0129] like Figure 9 As shown, this invention completely removes complex dynamic interference by performing time-domain multi-order decomposition and arithmetic mean extraction on the signal, and outputs a stable resistance value that reflects the intrinsic shear viscosity of the fluid.

[0130] like Figure 10 As shown, the comparative results fully demonstrate that the present invention not only completely eliminates the eccentric friction distortion phenomenon under high blockage ratio conditions, but also extends the upper limit of the effective test particle size to close to the pipe diameter limit, solving the physical defects that traditional experimental equipment cannot overcome.

[0131] The above inventions are merely a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A precision testing system for fluid resistance in confined spaces, characterized in that, include: A thermostatic container assembly includes an inner measuring tube and an outer sheath tube arranged coaxially, with the bottom of the outer sheath tube fixed inside a positioning clamp. The center guide assembly includes a guide wire arranged along the axis of the inner measuring tube, a self-centering base fixed to the bottom of the inner measuring tube, and a detachable positioning bracket fixed to the top of the inner measuring tube. The two ends of the guide wire are respectively fixed to the self-centering base and the detachable positioning bracket. The test sphere assembly includes a test sphere with a through cavity in the center, a self-lubricating bushing inside the cavity, and the self-lubricating bushing being slidably sleeved on the guide wire; A dynamic pressure suspension guide unit is disposed above the test sphere. The dynamic pressure suspension guide unit includes a dynamic pressure self-lubricating sleeve slidably sleeved on the guide wire. A plurality of evenly distributed support winglets are installed on the outer periphery of the dynamic pressure self-lubricating sleeve. The number of support winglets is even and they are radially distributed. A counterweight structure is installed at the end of the support winglets away from the dynamic pressure self-lubricating sleeve. Symmetrical hanging points are installed on any two radially symmetrical counterweight structures. The two symmetrical hanging points are connected to the test sphere through connectors. A precision drive and force measurement assembly includes a linear drive module, a force sensor, and a dual-line traction mechanism mounted on a gantry. The linear drive module adopts a ball screw slide structure. The force sensor is mounted on the moving part of the linear drive module and is connected to the dynamic pressure suspension guide unit through the dual-line traction mechanism. The dual-line traction mechanism includes a balance crossarm connected to the force sensor and two parallel traction lines that descend vertically from both ends of the balance crossarm. The ends of the two traction lines away from the balance crossarm are respectively connected to two symmetrical hanging points of the dynamic pressure suspension guide unit. The spokes of the detachable positioning bracket are provided with a plurality of opening slots for the radial entry and exit of the two traction lines, and the center of the detachable positioning bracket is provided with a quick-release clamp for locking the guide wire. The outer surface of the test sphere is provided with two symmetrically arranged traction interfaces. The two traction interfaces are respectively arranged with two symmetrical hanging points and two traction lines. The two traction lines are respectively connected to the connectors embedded in the two traction interfaces. The two traction interfaces are located in the range below the maximum sphere outline and above the lowest point of the sphere. The traction interfaces are filled with epoxy resin composite material, and the maximum radial dimension of the dynamic pressure suspension guide unit is smaller than the diameter of the test sphere.

2. The precision testing system for fluid resistance in confined spaces as described in claim 1, characterized in that, The inner measuring tube and the outer sheath tube are connected at both ends by sealing and centering flanges to form a sealed constant temperature cavity. The sealing and centering flanges are provided with sealing grooves that respectively seal and cooperate with the outer wall of the inner measuring tube and the inner wall of the outer sheath tube.

3. The precision testing system for fluid resistance in confined spaces as described in claim 1, characterized in that, The outer edge of the self-centering base is fitted with the inner wall of the inner measuring tube with a clearance, and the bottom end of the guide wire is fixed to the center of the self-centering base.

4. A test method based on the precision testing system for fluid resistance in a confined space according to any one of claims 1-3, characterized in that, Includes the following steps: In non-immersion conditions, the hydrodynamic self-lubricating sleeve is simply fitted onto the guide wire and connected to the traction line. The linear drive module drives the hydrodynamic self-lubricating sleeve to run along the guide wire at a preset speed sequence. The average tension value at different speeds is recorded by the force sensor to obtain the friction damping characteristic curve of the mechanical transmission system. After completing the calibration of the friction damping characteristic curve, the test ball is inserted into the guide wire and hung on the symmetrical hanging point of the counterweight structure through the connector. The linear drive module is driven to lower the test ball so that it is completely immersed in the fluid and lowered to the predetermined measurement depth starting position and left to stand still. After the fluid disturbance disappears and the force sensor reading stabilizes, the static reading is recorded to obtain the zero-point buoyancy reference. Based on the zero-point buoyancy benchmark calibration, the test sphere is pulled at a preset constant speed by the linear drive module to rise uniformly in the fluid, and the force sensor collects the total tension signal in real time during the motion process with a high sampling rate. Based on the obtained friction damping characteristic curve of the mechanical transmission system and the zero-point buoyancy reference, the collected total tension signal is differentially processed to obtain the pure fluid dynamic resistance value after deducting the effects of mechanical friction and buoyancy. Time-domain statistical analysis was performed on the pure fluid dynamic resistance value, and the arithmetic mean was extracted as the steady-state viscous resistance component, and the standard deviation was extracted as the fluid elastic fluctuation intensity. Constructing a dimensionless parameter fluctuation intensity factor Set the volatility intensity factor threshold range The flow field state is divided into domains: when When the flow field is determined to be dominated by laminar viscosity, only the steady-state viscous drag component is output as the final hydrodynamic drag value. when When the flow field is determined to be in the viscoelastic coupling transition region, the steady-state viscous drag component and the fluid elastic fluctuation intensity are dynamically decoupled and coupled to obtain the final fluid dynamic drag value and output it. when When wall slip or turbulent transition occurs in the flow field, a slip velocity correction term is introduced to compensate for the effective shear rate. The compensation calculation result is multiplied with the steady-state viscous drag component to obtain the final hydrodynamic drag value and output it.

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