A method and device for ultrasonic measurement of multiple physical parameters of a polymeric fluid

Abstract

The application discloses a kind of high polymer fluid multi-property parameter ultrasonic measurement method and device.The ultrasonic measurement method is propagated by waveguide from transducer to high polymer fluid in transparent container, and the multiple physical parameters of fluid, including sound velocity, sound attenuation coefficient, sound reflection coefficient, density, viscosity, modulus, are dynamically, real-time accurately measured and monitored.The device is by ultrasonic transducer, waveguide, fluid container, temperature control cavity, characterized in that further comprising ultrasonic emission device, fluid injection pump, air compressor, waste liquid collector, fixing device, water bath temperature control device, ultrasonic transducer is directly contacted with waveguide and is connected with ultrasonic emission device, waveguide is vertically distributed with fluid container side and is connected with fixing device, continuous injection pump is connected with fluid container, can realize the addition and cleaning of fluid sample, air compressor generates airflow for pipeline drying.

Description

A method and apparatus for ultrasonic measurement of multiple physical parameters of polymer fluids Technical Field

[0001] This invention relates to polymer fluid property parameter measurement technology, specifically a multi-property parameter ultrasonic measurement method and device. Background Technology

[0002] Fluid properties typically include density, viscosity, and modulus. Accurate measurement of these parameters is crucial for material synthesis and property monitoring. Polymer fluids, in particular, exhibit rich rheological properties and complex parameter variations. Real-time monitoring of fluid properties during flow is closely related to product quality. In recent years, the application of ultrasonic measurement of fluid properties has increased significantly. For example, Chinese patent CN202223341928.5 reports an ultrasonic transducer for fluid density measurement. This invention effectively reduces sound wave propagation, solving the problem of poor sound insulation due to a single sound-absorbing layer in existing technologies, and achieving fluid density measurement. Another example is Chinese patent CN202111184685.6, which reports an online synchronous detection system and method for fluid density and flow velocity. This invention can simultaneously detect fluid flow velocity and density in real time. US patent US2024377234(A1) proposes an ultrasonic measurement device and method for fluid flow velocity and flow rate.

[0003] Given the application of ultrasonic measurement in fluid measurement, there is still a lack of effective measurement methods and devices for multiple fluid properties, especially for real-time monitoring of polymer fluid properties. There is an urgent need for a measurement device and method for multiple fluid properties. Most existing ultrasonic measurement methods use a single probe and waveguide to determine the reflection coefficient and attenuation coefficient by reflecting the echo. The main problems are as follows: (1) Directly calculating the signal based on the time domain spectrum of the echo leads to a large error between the measured value and the actual value; (2) The measurement scenario is offline measurement rather than real-time monitoring, which is difficult to apply to measurement scenarios under continuous flow; (3) The measurement results are singular, mostly single-parameter measurements, and cannot achieve simultaneous measurement of multiple fluid properties. Ultrasonic waves are mechanical waves that rely on a medium for propagation. Due to the limitation of shear wave penetration distance, they can usually only propagate longitudinal waves in fluids. When ultrasonic waves are emitted from the probe, they pass through the waveguide to reach the polymer fluid, and then are reflected at the fluid container wall. During the entire propagation process, there are multiple reflection, transmission and diffraction behaviors. Accurately describing the ultrasonic propagation process behavior through mathematical models is the key to ensuring high-precision ultrasonic measurement results.

[0004] The above analysis shows that existing ultrasonic measurement methods and devices cannot accurately and in real-time measure the physical properties of polymer fluids, mainly including acoustic parameters (sound reflection coefficient and sound attenuation coefficient) and physical properties (density, viscosity, modulus). Within the scope of existing technology searches, no literature has been reported on ultrasonic measurement methods and devices for multiple physical properties of polymer fluids. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide an ultrasonic measurement device and method for multiple physical parameters of polymeric fluids. This device and method can achieve online and offline measurement of the density, viscosity, and modulus of polymeric fluids, with higher measurement accuracy. The device features a simple structure, wide measurement range, high measurement accuracy, strong applicability, and easy operation, and can be widely used in the measurement and online monitoring of basic fluid properties in the materials and chemical industries.

[0006] The technical solution of this invention to solve the aforementioned method problem is to design an ultrasonic measurement method for multiple physical parameters of polymer fluids. This method involves directly contacting an ultrasonic sensor with the polymer fluid sample via a waveguide rod, and dynamically and accurately measuring and monitoring the sound velocity, sound attenuation coefficient, sound reflection coefficient, density, viscosity, and modulus of the polymer fluid through coordinated control of the fluid injection pump and valves. The ultrasonic frequency range is 1-25 MHz, and the frequency can be adjusted by changing the probe. This method uses air to purge and dry the container and pipes, and uses the air as a reference signal.

[0007] The technical solution of this invention to solve the aforementioned device problem is to design an ultrasonic measurement device for multiple physical parameters of polymer fluids. This device includes a fixing device, a fluid container, a waveguide rod, an ultrasonic probe, an ultrasonic generator, and a computer. Its distinguishing feature is that it also includes a fluid injection pump, an air compressor, pipeline valves, and a fluid collection device. The fluid container is fixed by the fixing device and directly connected to the waveguide rod on one side. The fluid injection pump is connected to the fluid container via a fluid pipeline. The fluid collection device is connected downstream of the fluid container via a pipeline. The fluid container's temperature is controlled by a circulating water bath. The two ends of the waveguide rod are in contact with the fluid being measured and the ultrasonic probe, respectively. The probe is connected to the ultrasonic generator via a wire to generate ultrasonic waves. The ultrasonic generator is connected to the computer to record and process the measured waveforms.

[0008] Compared with the prior art, the measuring device and method of the present invention can simultaneously measure more fluid properties while satisfying the measurement of single physical parameters. It can not only satisfy the physical property measurement of static fluids, but also the real-time monitoring of flowing fluids. By mathematically modeling the ultrasonic propagation process, the error of the measurement results can be reduced. It has the following technical effects: (1) The present invention realizes the ultrasonic measurement of multiple physical parameters of polymer fluids, avoiding the limitation of traditional ultrasonic measurement that only has single parameter measurement results; (2) The present invention realizes the real-time monitoring of fluid physical parameters in static and flowing states; (3) When measuring in static and flowing states, by mathematically modeling the ultrasonic propagation process, the present invention not only improves the accuracy of fluid physical parameter measurement results, but also enables the measurement results to reflect the real change law of fluid characteristics. Attached Figure Description

[0009] Figure 1 is a schematic diagram of the composition structure of one specific embodiment of the ultrasonic measurement device for multiple physical parameters of polymer fluids according to the present invention.

[0010] Figure 2 shows a schematic diagram of the installation of the waveguide rod and the polymer fluid cavity. The axis of the waveguide rod is perpendicular to one side of the sample box. One end of the waveguide rod is connected to the ultrasonic probe, and the other end is in direct contact with the polymer fluid in the sample box. The sample box wall and the waveguide rod are connected by threads. The water bath cavity wall and the waveguide rod are sealed with a rubber stopper to prevent leakage of circulating water.

[0011] Figure 3 is a schematic diagram of ultrasonic echo, where Figure 3(a) is the reference signal and Figure 3(b) is the sample signal. The corresponding waveform ① is the first echo, waveform ② is the second echo at the waveguide-solution interface, and waveform ③ is the third echo reflected on the left side wall of the container after passing through the sample. Detailed Implementation

[0012] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0013] This invention discloses an ultrasonic measurement device (hereinafter referred to as the measurement device, see Figures 1-2) and method for measuring multiple physical parameters of polymer fluids. The measurement device is applicable to the method for measuring multiple physical parameters of polymer fluids described in this invention. The device is characterized by comprising a fixing device 9, a fluid container 5, a waveguide rod 4, an ultrasonic probe 3, an ultrasonic generator 2, and a computer 1. It also includes a fluid injection pump 6, an air compressor 7, a pipeline valve 8, and a fluid collection device 10. The fluid container 5 is fixed by the fixing device 9 and directly connected to the waveguide rod 4 on one side. The fluid injection pump 6 is connected to the fluid container 5 via a fluid pipeline. The fluid collection device 10 is connected downstream of the fluid container 5 via a pipeline 14. The fluid container 5 uses a circulating water bath to control the measurement temperature. The two ends of the waveguide rod 4 are in contact with the fluid being measured and the ultrasonic probe 3, respectively. The ultrasonic probe 3 is connected to the ultrasonic generator 2 via a wire 13 to generate ultrasonic waves. The ultrasonic generator 2 is connected to the computer 1 to record and process the measured waveforms.

[0014] The waveguide rod 4 (see Figure 2) of the measuring device of this invention is composed of a quartz glass rod 18, epoxy resin 15, and a stainless steel sleeve 16. The epoxy resin 15 not only fixes the quartz glass rod 18 and the stainless steel sleeve 16, filling the gap between them, but also reduces boundary noise reflection during the propagation of ultrasonic waves through the quartz glass rod 18. One end of the waveguide rod is adjacent to the ultrasonic probe, and the diameter of the quartz glass rod 18 in the waveguide rod is larger than the diameter of the ultrasonic probe 3. The probe is connected to one end of the waveguide rod through a coupling agent 17. The other end of the waveguide rod is connected to the fluid container 5 through a thread. This end face is in contact with the test sample. The container wall and the waveguide rod 4 are sealed with a rubber stopper to prevent leakage of the water bath liquid.

[0015] The measurement method corresponding to the measuring device of this invention is based on the following principle: the ultrasonic waves excited by the ultrasonic probe 3 are transmitted to the fluid being measured through the waveguide rod 4. When there is no liquid in the fluid container 5, the ultrasonic waves undergo total reflection at the waveguide rod-air interface. At this time, the corresponding waveform includes two echoes ① and ② (see Figure 3(a)). The first echo ① is formed near the end face of the waveguide rod 4 close to the ultrasonic probe 3, while the second echo ② is formed at the waveguide rod-air interface. The second echo ② serves as a reference signal for analyzing the physical properties of the sample. When the fluid container 5 contains the liquid being measured, the measured signal is shown in Figure 3(b). At this time, the ultrasonic signal is transmitted to the fluid being measured through the waveguide rod 4, and then reflected by the sample box wall to generate a third echo ③. This echo carries the sample information of the fluid being measured. Since the fluid measurement depth is known, the fluid sound velocity c can be determined based on the flight time of the two echoes ② and ③. The sound attenuation coefficient α of the fluid being measured can be determined based on the amplitude values ​​of the two echoes. The density ρ of the fluid under test can be calculated based on the reflection coefficient R at the interface of the reference signal and the sample signal. By performing a Fourier transform on the echo signal, the sound attenuation coefficient and sound velocity at different frequencies can be calculated, thereby deriving the viscosity and modulus of the fluid under test, and finally realizing the simultaneous measurement of multiple physical parameters of the fluid under test.

[0016] The measuring device of this invention has the following functions: (1) The depth of the sample can be measured by rotating the waveguide rod close to the thread on the side of the sample box of the fluid being measured. (2) The ultrasonic measurement frequency can be changed by changing the ultrasonic probe. (3) Different temperature measurement conditions and fluid property parameters under varying temperature conditions can be set by controlling the water bath temperature controller. (4) Real-time measurement of static and dynamic fluid states can be achieved by controlling the closing of the upstream and downstream pipeline valves. (5) Fluid property parameters can be measured under different pressures by turning on the upstream fluid injection pump and closing the downstream valve.

[0017] Any aspects not covered in this invention are applicable to existing technologies.

[0018] Specific embodiments of the present invention are given below. These embodiments are only used to further illustrate the present invention, but do not limit the scope of protection of the claims of the present invention.

[0019] Example 1

[0020] This embodiment uses the measuring device described in this invention (as shown in Figure 1) to measure the physical properties of a polyethylene oxide (PEO) aqueous solution (shear-thinning fluid). The parameters are as follows:

[0021] The excitation voltage of the ultrasonic generator 2 is 300 V, and the ultrasonic probe 3 used is a broadband probe with a center frequency of 5 MHz and an effective bandwidth range of 2.5 ~ 7.5 MHz. The test temperature of the PEO aqueous solution is set to 25 ℃ at room temperature. The temperature of the test solution is controlled within the target temperature range by the water bath temperature controller 11 to achieve constant temperature measurement at 25 ℃. The molecular weight of the PEO used in the experiment is 1 million. The specific measurement method is as follows: (1) Preparation before the test: Empty the container 5 containing the fluid to be tested, open the pipeline valve 8, and clean the pipeline 12 and the fluid container 5 by injecting deionized water into the fluid injection pump 6. Then, inject anhydrous ethanol into the fluid injection pump 6 to deeply clean the pipeline and sample box. Next, turn off the fluid injection pump 6, turn on the air compressor 7, and introduce air into the pipeline and the fluid container 5 until there is no residual deionized water and anhydrous ethanol in the entire pipeline and sample box. (2) Turn off the air compressor 7, turn on the ultrasonic generator device 2 switch and the computer 1, and collect the reference signal. (3) Turn on the fluid injection pump 6 and transport the sample to be tested through the pipe 12 to the fluid holding container 5. When the sample flows into the downstream fluid collection device 10, close the pipe valves 8 at both ends of the upstream and downstream pipes at the same time, so that the sample to be tested in the fluid holding container 5 remains in a static and stable state. (4) Adjust the water bath temperature controller 11, set the corresponding measurement temperature, wait for 30 minutes of circulating water bath time to stabilize the measurement temperature of the fluid to be tested, and then turn on the ultrasonic generator device 2 switch and the computer 1 to collect the sample signal. (5) By comparing the reference signal and the sample signal, the ultrasonic emission coefficient of the waveguide interface can be calculated, and then the density of the PEO aqueous solution can be calculated according to the relationship between acoustic impedance, density and sound velocity. Repeat the above 5 steps to measure the density, viscosity and modulus changes of different mass concentrations and molecular weights. The measurement results show that the density, viscosity and modulus obtained by ultrasonic measurement are basically consistent with the physical property parameters of pure water at room temperature of 25 ℃, and the measurement accuracy of the three physical property parameters is greater than 97%. Meanwhile, the density, viscosity, and modulus of PEO aqueous solution are directly proportional to the mass concentration and molecular weight of PEO.

[0022] This embodiment demonstrates that the ultrasonic measuring device and method of the present invention can realize real-time measurement of the physical properties of polymer fluids under dynamic and static conditions, including the sound velocity, sound attenuation coefficient, density, viscosity and modulus of the fluid.

[0023] Example 2

[0024] To verify the accuracy of this invention in Newtonian fluids, offline measurements were performed using glycerol / water solutions of different ratios. This embodiment uses the measuring device described in this invention (as shown in Figure 1) to perform offline measurements of the physical properties of glycerol aqueous solution (Newtonian fluid). The testing procedure includes: (1) Preparation: Cleaning the pipeline and collecting air reference signals according to Example 1; (2) Sample injection: Injecting glycerol aqueous solution and closing the upstream and downstream pipeline valves 8 to allow the sample to stand; (3) Temperature control: Setting a temperature range of 20–40 ℃, measuring every 5 ℃; (4) Ultrasonic acquisition: Obtaining echo sequences using a broadband probe with a center frequency of 10 MHz. The measurement results obtained in this embodiment show that: the sound velocity of the glycerol aqueous solution decreases monotonically with increasing temperature; the attenuation coefficient increases significantly with increasing glycerol concentration; the calculated density is consistent with literature data by more than 98%; and the viscosity calculation results deviate from those of the rotational viscometer by less than 5%.

[0025] This embodiment demonstrates that the measurement method of the present invention can obtain high-precision physical property parameters in Newtonian fluids, and can also serve as an effective verification method for the measurement method.

[0026] Example 3

[0027] This embodiment demonstrates the ability of the present invention to monitor non-Newtonian fluids in real time under continuous flow conditions. This embodiment uses the measuring device described in the present invention (as shown in Figure 1) to measure the physical properties of a corn starch aqueous solution (a shear-thickening fluid). The corn starch aqueous solution is a typical shear-thickening fluid, exhibiting a rapid increase in viscosity in the high-shear region. The measurement process of this embodiment includes: (1) Setting up the flow scenario: opening the valve 8 of the upstream injection pump and the downstream collection device pipeline, setting the flow rate range to 10~100 mL / min; (2) Starting the flow rate change experiment: recording 30 s of continuous ultrasonic signals at each flow rate, and converting the flow velocity into the fluid's shear rate parameters based on the geometric dimensions; (3) Starting ultrasonic acquisition and signal processing, and calculating the changes in sound velocity, attenuation coefficient, and modulus with the flow velocity in real time. The measurement results obtained in this embodiment show that: in the low flow velocity (shear rate) region, the viscosity remains stable; when the flow velocity exceeds the critical value, the sound attenuation coefficient and equivalent modulus suddenly increase, reflecting the enhancement of the fluid's microstructure induced by shear; the online measurement method proposed in this invention can accurately capture the time point of shear thickening.

[0028] Example 4

[0029] Boger fluid exhibits near-constant viscosity but significant elasticity. This embodiment verifies the invention's ability to measure viscoelastic parameters by performing ultrasonic measurements on an aqueous solution of polyvinylpyrrolidone (PVP). This embodiment uses the measuring device described in this invention (as shown in Figure 1) to measure the physical properties of PVP aqueous solutions with different mass fractions (2-10%). The specific implementation steps include: (1) determining the sound velocity, attenuation, and reflection coefficient using an offline measurement mode; (2) maintaining stable fluid flow by adjusting pipeline valve 8 in an online mode; and obtaining changes in storage modulus and loss modulus based on frequency domain analysis. The measurement results obtained in this embodiment show that: the sound velocity changes little with concentration, but the attenuation coefficient increases linearly with increasing frequency; the storage modulus increases slightly with the flow shear rate, consistent with the weak shear sensitivity characteristics of Boger fluid. This embodiment demonstrates that the invention can simultaneously acquire fluid elasticity and acoustic parameters on the same platform.

[0030] The ultrasonic multi-property parameter measurement method proposed in this invention has high universality. Its core measurement is based on the echo characteristics (sound velocity, reflection coefficient, attenuation coefficient) in the acoustic overtone process and the general relationship between acoustic impedance and material viscoelasticity. Therefore, it can be applied to a variety of systems, including but not limited to: (1) Newtonian fluids: such as alcohols, sugar solutions, salt solutions, homogeneous monomer solutions, etc. (2) Shear-thinning fluids: including polymer solutions such as PEO, PAM, CMC, hyaluronic acid, alginate, etc. (3) Shear-thickening fluids: nanoparticle suspensions, starch, clay systems, etc. (4) Viscoelastic fluids and Boger fluids: such as PVP, PI, PAAm, silicone oil polymer mixtures, etc. (5) Industrial slurries: ceramic slurries, catalyst slurries, battery electrode slurries, coatings, etc. (6) Biological and food systems: protein solutions, emulsions, colloidal food matrices, etc. (7) Industrial reaction systems: polymerization reaction intermediate liquids, enzyme catalytic suspensions, fermentation broths and process monitoring fluids, etc.

[0031] In summary, the method of the present invention is not only applicable to the above embodiments, but can also be extended to more types of complex fluid systems according to the application scenario, so as to achieve high-precision, multi-parameter, dynamic real-time monitoring.

Claims

1. A method for ultrasonic measurement of multiple physical parameters of polymer fluids, characterized in that, Includes the following steps: An ultrasonic sensor is brought into direct contact with the polymer fluid sample via a waveguide. The flow state of the polymer fluid sample is controlled by a fluid injection pump and valves. Air is used as a reference signal, and the second echo generated during total internal reflection at the waveguide-air interface is used as the reference signal. When the fluid container contains the polymer fluid being tested, the ultrasonic signal is transmitted through the waveguide to the fluid, and the third echo generated after reflection from the sample container wall is used as the sample signal. The velocity of sound in the polymer fluid is determined based on the time difference between the second and third echoes and the known fluid measurement depth. The acoustic attenuation coefficient of the polymer fluid is determined based on the amplitude values ​​of the second and third echoes. The density of the polymer fluid is calculated based on the reflection coefficients of the reference signal and the sample signal at the waveguide-fluid interface. The echo signal is subjected to Fourier transform to calculate the sound attenuation coefficient and sound velocity at different frequencies, thereby deriving the viscosity and modulus of the polymer fluid; this enables dynamic and real-time measurement and monitoring of the sound velocity, sound attenuation coefficient, sound reflection coefficient, density, viscosity, and modulus of the polymer fluid; wherein, the ultrasonic sensor corresponds to an ultrasonic frequency range of 1-25 MHz, and the frequency of the ultrasonic wave is adjusted by changing the probe.

2. The ultrasonic measurement method for multiple physical parameters of polymer fluids according to claim 1, characterized in that, The containers and pipes are emptied and dried using air.

3. A measuring device for implementing the ultrasonic measurement method for multiple physical parameters of polymer fluids as described in claim 1 or 2, characterized in that, The device includes: a fixing device, a fluid container, a waveguide rod, an ultrasonic probe, an ultrasonic generator, and a computer; a fluid injection pump, an air compressor, pipeline valves, and a fluid collection device; the fluid container is fixed by the fixing device and directly connected to the waveguide rod on one side; the fluid injection pump is connected to the fluid container via a fluid pipeline; the fluid collection device is connected downstream of the fluid container via a pipeline; the fluid container uses a circulating water bath to control the temperature; the two ends of the waveguide rod are in contact with the fluid being measured and the ultrasonic probe, respectively; the ultrasonic probe is connected to the ultrasonic generator via a wire to generate ultrasonic waves; the ultrasonic generator is connected to the computer to record and process the measured waveforms.

4. The measuring device according to claim 3, characterized in that, The waveguide rod is directly connected to the ultrasonic probe via a coupling agent, and the diameter of the waveguide rod is larger than the diameter of the ultrasonic probe.

5. The measuring device according to claim 3, characterized in that, Ultrasonic measurements of polymer fluids under dynamic and static flow conditions are achieved by adjusting the valves in the pipeline.

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