The microstructural evolution and apparent viscosity of hypereutectic Al-24%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 720 d...The microstructural evolution and apparent viscosity of hypereutectic Al-24%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 720 degreesC to eutectic temperature, the primary Si crystals were gradually changed from elongated platelets to near-spherical shapes. It was found that some nondendritic a-phase formed when the melt was stirred below 585 degreesC. The experiment showed that the semi-solid stirring had strong effect on inhibiting the anisotropic growth of Si crystals during solidification. The apparent viscosity of the alloy melt increased slowly with the decreasing of temperature before the formation of nondendritic alpha -phase, which caused the dramatic increase of apparent viscosity.展开更多
This study investigated the rheological properties of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry prepar...This study investigated the rheological properties of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry preparing, delivering and model filling. The rheological properties of SSM （semi-solid metal） slurry was described by an analytical model in terms of microstructural parameters, which consist of effective solid fraction, particle size and shape, and flow parameters such as mean velocity, fluctuant velocity and relative velocity between liquid and solid phase. The model was verified in the experiment of A356 alloys with a coaxial double-bucket rheometer. And the maximum relative error between the theoretical value and measured one is less than 20%. The results of experiment and theoretical calculation also indicate that the microstructural parameters and flow parameters are two major factors that affect the apparent viscosity of semi-solid alloys, and fluctuant velocity and relative velocity between liquid and solid phase are the key factors to distinguish between steady and transient rheological properties.展开更多
The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results ...The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results in this paper indicate that the viscous friction between semi-solid metal and pipe wall, the collisions among the solid particles, and the liquid flow around particles are the three main types of energy dissipation. On the basis of the hydromechanics, the energy dissipation calculation model is built. It is demonstrated that the micro-structural parameters such as effective solid fraction, particle size and shape, and flow parameters such as the mean velocity, the fluctuant velocity of particles and the relative velocity between the fluid and solid phase, affect the energy dissipation of semi-solid metal.展开更多
Accurate prediction of apparent viscosity and analyzing the influence mechanism of particle behavior on apparent viscosity is of great importance for the semi-solid processing process.In this paper,the coupled CFD-DEM...Accurate prediction of apparent viscosity and analyzing the influence mechanism of particle behavior on apparent viscosity is of great importance for the semi-solid processing process.In this paper,the coupled CFD-DEM method is employed to study the solid-liquid two phase flow and particle behavior in semisolid aluminum.The artificial neural networks method is used to predict the lubrication force range and calculate the apparent viscosity of semi-solid aluminum.The results show that the increasing shear rate results in the increasing coordination number of clusters,indicating that the spherical evolution of clusters caused by shear is important reason for the shear thinning of semi-solid metal.The blockage caused by the large cluster formed under high solid volume fraction leads in the high apparent viscosity.Predicting the apparent viscosity of semi-solid metal must consider the particle agglomeration behavior.Based on artificial neural networks method,the apparent viscosity of semi-solid metal can be estimated accurately by predicting the lubrication force range under different solid volume fractions and shear conditions.展开更多
Apparent viscosity is an important parameter for glucose syrup production.which is greatly affected by particle size and concentration of samples.In order to analyze the factors influencing the apparent viscosity,the ...Apparent viscosity is an important parameter for glucose syrup production.which is greatly affected by particle size and concentration of samples.In order to analyze the factors influencing the apparent viscosity,the particle size distribution,steady shear flow behavior,temperature,and time sweep test of native degerminated maize grits(NDMG),extruded degerminated maize grits(EDMG),and enzymatically extruded degerminated maize grits(EEDMG)with different particle sizes(passed through 20,40,60,80,and 100 mesh sieves)and concentrations(water-sample ratios:2:1,3:1,5:1,10:1,and 20:1)were investigated.All samples passed through different mesh sieves showed a gradient and a relatively concentrated distribution,and slurries had typical shear-thinning properties.Apparent viscosity increased with increasing particle size and concentration.The lowest apparent viscosity was attained from the samples obtained at 100+mesh and 20:1 water-sample ratio.Moreover,the sample with a 20:1 water-sample ratio showed the most stable apparent viscosity in the temperature sweep test.In the time sweep test,the power law equation with high determination coefficients(R^(2)=0.9446,0.9382)and low root mean square error(RMSE=0.0002)had the best fit to the experimental data of the EDMG and EEDMG samples passed through 100+mesh.Overall,the lower apparent viscosities of the EDMG and EEDMG samples obtained at 100+mesh and 20:1 water-sample ratio can improve the activity and accessibility of enzymes for glucose syrup production.This study provides critical insight into decreased apparent viscosity and expands the uses of EDMG and EEDMG in the glucose syrup sector.展开更多
The apparent viscosity reflects the resistance of the fluidized medium in the bed to the beneficiation particles,which directly affects the separation time and mismatch content.So,the falling-ball method was used to m...The apparent viscosity reflects the resistance of the fluidized medium in the bed to the beneficiation particles,which directly affects the separation time and mismatch content.So,the falling-ball method was used to measure the apparent viscosity of a binary medium in a pulsed fluidized bed by varying the gas velocity,pulsation frequency,and fine particle content.The results show that with increasing gas velocity and fine particle content,the apparent viscosity of the bed gradually decreased,whereas it first decreased and then increased with pulsation frequency increasing and achieved a minimum value in the range of 4-6 Hz.Within limits,the adjustment of gas velocity and fine content can effectively reduce the apparent viscosity and improve the separation process.A model for predicting the apparent viscosity in a pulsation separation fluidized bed was established with good accuracy.展开更多
Being one of the most commonly performed EOR methods, polymer injection is used to increase themobility ratio and decrease water relative permeability to allow the injected fluid to sweep more oiltowards the productio...Being one of the most commonly performed EOR methods, polymer injection is used to increase themobility ratio and decrease water relative permeability to allow the injected fluid to sweep more oiltowards the production well. Before the polymer solution is injected into the reservoir through the injection wells, the process of polymer injection must be simulated using commercial numerical reservoirsimulators. In order to be able to simulate the process, the viscosity behavior of the solution must beknown. Therefore, a model is required to estimate the viscosity of the injected fluids versus shear rateand polymer concentration. In this study, a new mathematical function based on the power-law fluidequation is presented, which can be applied to predict the viscosity of SPAM solutions. The two requiredparameters of the power-law equation are obtained by fitting a power-law function to the viscosity-shearrate data. Samples in different polymer concentrations (using two SPAM polymers with different molecular weights) were prepared and their viscosity was measured against different shear rates. The results were fitted to the power-law equation and their corresponding power-law parameters wererecorded. A mathematical function was introduced and tested for each parameter. The new functionscombined with the power-law equation were used to estimate the viscosity of different polymer solutions with different SPAM concentrations. The results showed that the model is capable of estimating theviscosity with acceptable precision. Furthermore, it is applicable in various temperatures and watersalinities.展开更多
Efficient dry separation is essential for utilizing low-grade oil shale.This study developed a ternary high-density gas–solid fluidized bed system using ferrosilicon powder,magnetite powder,and D-class oil shale part...Efficient dry separation is essential for utilizing low-grade oil shale.This study developed a ternary high-density gas–solid fluidized bed system using ferrosilicon powder,magnetite powder,and D-class oil shale particles,focusing on the impact of apparent viscosity on particle settling.Results showed that viscosity was influenced by medium composition,particle size,and flow structure.In the binary system of B−silicon and B+magnetite,minimum viscosity(0.782 Pa s)was reached at a 40%ferrosilicon ratio.In the ternary system,viscosity increased nonlinearly with oil shale content,with 8%being the critical threshold where fluidization stability declined.Gas velocity significantly affected viscosity distribution,with moderate increases improving flow uniformity and reducing viscosity by 32%–40%.However,excessive velocity caused bubble coalescence and increased viscosity fluctuations,with standard deviation rising from 0.0065 to 0.0191 Pa s.Sedimentation tests showed that the middle bed region provided optimal separation at low gas velocity,while higher velocities shifted separation to the upper region.When gas velocity exceeds 0.45 m/s,the best separation efficiency is achieved.This study clarifies the relationship between viscosity and separation performance,providing guidance for optimizing dry oil shale separation.展开更多
Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent vi...Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent viscosity was also determined in Hele-Shaw cell In order to investigate the foam performance at static and dynamic conditions. Results show that the maximum adsorption of surfactant on the nanoparticles occurs at 3 wt% surfactant concentration. Foam stability increases while the foamability decreases with the increasing nanoparticle concentration. However, optimum nanoparticle concentration corresponding to maximum foam stability was obtained at 1.0 wt% nanoparticle concentration for the hydrophilic SiO_2/SDS and Al_2O_3/SDS foams. Foam performance was enhanced with increasing nanoparticles hydrophobicity. Air-foams were generally more stable than CO_2 foams.Foam apparent viscosity increased in the presence of nanoparticles from 20.34 mPa·s to 84.84 mPa·s while the film thickness increased from 27.5 μm to 136 μm. This study suggests that the static and dynamic stability of conventional foams could be improved with addition of appropriate concentration of nanoparticles into the surfactant solution. The nanoparticles improve foam stability by their adsorption and aggregation at the foam lamellae to increase film thickness and dilational viscoelasticity. This prevents liquid drainage and film thinning and improves foam stability both at the bulk and bubble scale.展开更多
Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic l...Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr^3＋ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr^3＋, and a cross-linked polymer （CLP） system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity （namely storage modulus, loss modulus, and first normal stress difference） increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low- permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection （HPAM-1, Cr^3＋ as the cross linker） is 3.1% to 5.2% higher than that by HPAM- 2 injection.展开更多
This paper presents the rheological behaviour of supercritical CO2 （sCO2） foam at reser- voir conditions of I 500 psi and 80 ℃. Different commercial surfactants were screened and utilized in or- der to generate a f...This paper presents the rheological behaviour of supercritical CO2 （sCO2） foam at reser- voir conditions of I 500 psi and 80 ℃. Different commercial surfactants were screened and utilized in or- der to generate a fairly stable CO2 foam. Mixed surfactant system was also introduced to generate strong foam. Foam rheology was studied for some specific foam qualities using a high pressure high tempera- ture （HPHT） foam loop rheometer. A typical shear thinning behaviour of the foam was observed and a significant increase in the foam viscosity was noticed with the increase of foam quality until 85%. A de- sired high apparent viscosity with coarse texture was found at 85% foam quality. Foam visualization above 85% showed an unstable foam due to extremely thin lamella which collapsed and totally disap- peared in the loop rheometer. Below 52%, a non-homogenous and unstable foam was found having low viscosity with some liquid accumulation at the bottom of the circulation loop. This research has demon- strated rheology of sCO2 foams at different qualities at HPHT to obtain optimal foam quality region for immiscible CO2 foam co-injection process.展开更多
The hydrodynamic performance of three mixers single shaft central mixer(SSC), single shaft off-centred mixer(SSO), dual shaft off-centred mixer(DSO), was investigated in the mixing of yield-pseudoplastic fluids(xantha...The hydrodynamic performance of three mixers single shaft central mixer(SSC), single shaft off-centred mixer(SSO), dual shaft off-centred mixer(DSO), was investigated in the mixing of yield-pseudoplastic fluids(xanthan gum solutions) in the laminar regime. To explore and determine the efficiency of three mixers, both numerical and experimental approaches were adopted. The fluid rheology was described by the Herschel–Bulkley rheological model. Computational fluid dynamics was employed to simulate the apparent viscosity distribution, mixing time, and the flow pattern inside the stirred tank. The developed model was validated through experimentally measured torque. The influence mechanism of the rotational speed and fluid rheology on the cavern evolution was explored deeply. The performances of three mixers in this work were compared at the constant power input and fluid rheology with respect to the flow pattern, mixing time, and mixing efficiency. The results verify that the faster the rotating speed, the greater influence of the fluid rheology on the cavern evolution, and the more uniform apparent viscosity distribution. Moreover, the mixing time decreases continuously as the increasing power consumption per unit volume, and the dimensionless mixing time of DSO mixer was nearly 42.8% and 6.1% shorter than that of SSC and SCO mixer at the same Reynolds number, respectively. According to the mixing efficiency criteria, these data also revealed that DSO was more efficient than SSC and SSO.展开更多
The further application of semi-solid processing lies in the in-depth fundamental study like rheological behavior. In this research, the apparent viscosity of the semi-solid slurry of 7075 alloy was measured using a C...The further application of semi-solid processing lies in the in-depth fundamental study like rheological behavior. In this research, the apparent viscosity of the semi-solid slurry of 7075 alloy was measured using a Couette type viscometer. The effects of solid fraction and shearing rate on the apparent viscosity of this alloy were investigated under different processing conditions. It can be seen that the apparent viscosity increases with an increase in the solid fraction from 10% to 50% （temperature 620 ℃ to 630 ℃） at steady state. When the solid fraction was fixed, the apparent viscosity can be decreased by altering the shearing rate from 61.235 s-1 to 489.88 s-1 at steady state. An empirical equation that shows the effects of solid fraction and shearing rate on the apparent viscosity is fitted： ηα = [0.871 - 0.00849. γ0.74924]. exp（3.7311, fs） . The microstructure of quenched samples was examined to understand the alloy＇s rheological behavior.展开更多
Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble-150...Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble-1500D simulator and the true stress-strain curves were given directly. The relationship of apparent viscosity vs temperature, shear rate and holding time of the three kinds of semi-solid magnesium alloys, as well as isothermal steady state rheological characteristic and mechanical behavior were studied. The results show that the three magnesium alloys had the characteristic of shear-thinning. The rheological characteristic of the semi-solid MB15 is different from that of semi-solid AZ91D. The semi-solid MB15 has higher apparent viscosity and deformation resistance.展开更多
Objective: To study the effects of L.F04, the active fraction of Lycopus lucidus, on erythrocytes rheological property so as to investigate its mechanism in promoting blood circulation and removing blood stasis. Metho...Objective: To study the effects of L.F04, the active fraction of Lycopus lucidus, on erythrocytes rheological property so as to investigate its mechanism in promoting blood circulation and removing blood stasis. Method: The effects of L.F04 (used for treatment for 10 days in different dosages) on deformability, aggregation and membrane liquidity of erythrocytes (MLE) as well as whole blood apparent viscosity (η_b) were examined on the basis of rat model of blood-stasis syndrome induced by venous injection of high molecular weight dextran. Result: As compared with the normal control group, the model group's RBC deformability and MLE were lower, and the aggregation of erythrocytes and η_b were higher. Compared with the model group, both L.F04 0.612g/kg and 0.306g/kg showed significant effect in improving deformability and inhibiting aggregation of red blood cells (RBC) and reducing blood viscosity. The trend of improving MLE was also shown. Conclusion: L.F04 could significantly improve the abnormal rheological property of erythrocytes.展开更多
The flotation separation of chalcopyrite and talc is challenging due to their similar natural floatability characteristics.Besides,it is usually difficult to effectively inhibit talc by adding sodium carboxymethyl cel...The flotation separation of chalcopyrite and talc is challenging due to their similar natural floatability characteristics.Besides,it is usually difficult to effectively inhibit talc by adding sodium carboxymethyl cellulose(CMC)alone during chalcopyrite flotation.Here,a combined inhibitor comprising acidified sodium silicate(ASS)and CMC was employed to realize effective flotation separation of chalcopyrite and talc,and the combined inhibition mechanism was further investigated.Microflotation results showed that adding ASS strengthened the inhibitory effect of CMC on talc and improved the separation of chalcopyrite and talc.The zeta potential,Fourier transform infrared,and X-ray photoelectron spectroscopy analysis indicated that CMC was mainly adsorbed on the talc surface via hydroxyl and carboxyl groups.Moreover,the addition of ASS improved the adsorption of carboxyl groups.Furthermore,the adsorption experiments and apparent viscosity measurements revealed that adding ASS dispersed the pulp well,which reduced the apparent viscosity,improved the adsorption amount of CMC on the talc surface,and enhanced the inhibition of talc in chalcopyrite flotation.展开更多
The rheological behavior of semisolid Mg_(2)Si/AM60 composites prepared by ultrasonic vibration treatment was investigated.The effects of primaryα-Mg solid content,the ultrasonic power and the content of reinforcemen...The rheological behavior of semisolid Mg_(2)Si/AM60 composites prepared by ultrasonic vibration treatment was investigated.The effects of primaryα-Mg solid content,the ultrasonic power and the content of reinforcement phase Mg_(2)Si on the apparent viscosity of semisolid composites were discussed.The results show that the apparent viscosity of the semis olid composites increases with the increase in a-Mg solid content.Meanwhile,the apparent viscosity decreases with the increase in ultrasonic power,and the reduction amplitude is higher when the solid content is higher.In addition,the apparent viscosity increases with the increase in Mg_(2)Si content.Based on experimental data fitting,the rheological model of semisolid Mg_(2)Si/AM60 composites prepared by ultrasonic vibration was established.展开更多
The rheological behavior of semi-solid AZ91D magnesium alloy was investigated in isothermal steady state condition. The effects of stirring temperature and shearing rate on apparent viscosity of semi-solid alloy slurr...The rheological behavior of semi-solid AZ91D magnesium alloy was investigated in isothermal steady state condition. The effects of stirring temperature and shearing rate on apparent viscosity of semi-solid alloy slurry at steady state were discussed. The results show that the apparent viscosity of semisolid AZ91D alloy increases with increasing solid fraction. It increases slightly before the solid fraction reaches a certain value, about 0.4, and then goes up rapidly aider the solid fraction reaches the critical value. However, the apparent viscosity decreases with increasing shearing rate, and the reduction amplitude is higher when the solid fraction is higher. According to the experimental data, an empirical equation that shows the effect of solid fraction and sheafing rate on the apparent viscosity of semi-solid AZ91D alloy can be built as ηa=9.7×10^-2 exp（13.87fs）γ^-0.58.展开更多
Detailed experimental investigations were carried out for microwave pre-treatment of high ash Indian coal at high power level(900 W) in microwave oven. The microwave exposure times were fixed at60 s and 120 s. A rheol...Detailed experimental investigations were carried out for microwave pre-treatment of high ash Indian coal at high power level(900 W) in microwave oven. The microwave exposure times were fixed at60 s and 120 s. A rheology characteristic for microwave pre-treatment of coal-water slurry(CWS) was performed in an online Bohlin viscometer. The non-Newtonian character of the slurry follows the rheological model of Ostwald de Waele. The values of n and k vary from 0.31 to 0.64 and 0.19 to 0.81 Pa·sn,respectively. This paper presents an artificial neural network(ANN) model to predict the effects of operational parameters on apparent viscosity of CWS. A 4-2-1 topology with Levenberg-Marquardt training algorithm(trainlm) was selected as the controlled ANN. Mean squared error(MSE) of 0.002 and coefficient of multiple determinations(R^2) of 0.99 were obtained for the outperforming model. The promising values of correlation coefficient further confirm the robustness and satisfactory performance of the proposed ANN model.展开更多
Under the condition of die casting and reheating temperature of 570-580 degC, the rheological behavior of semi-solid aluminum alloy (A356) is pseudoplasticity at the shearrate of 2X10^-1X10^4s^(-1), and also shows dil...Under the condition of die casting and reheating temperature of 570-580 degC, the rheological behavior of semi-solid aluminum alloy (A356) is pseudoplasticity at the shearrate of 2X10^-1X10^4s^(-1), and also shows dilatancy at the rate over 10~6s^(-1).展开更多
文摘The microstructural evolution and apparent viscosity of hypereutectic Al-24%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 720 degreesC to eutectic temperature, the primary Si crystals were gradually changed from elongated platelets to near-spherical shapes. It was found that some nondendritic a-phase formed when the melt was stirred below 585 degreesC. The experiment showed that the semi-solid stirring had strong effect on inhibiting the anisotropic growth of Si crystals during solidification. The apparent viscosity of the alloy melt increased slowly with the decreasing of temperature before the formation of nondendritic alpha -phase, which caused the dramatic increase of apparent viscosity.
文摘This study investigated the rheological properties of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry preparing, delivering and model filling. The rheological properties of SSM （semi-solid metal） slurry was described by an analytical model in terms of microstructural parameters, which consist of effective solid fraction, particle size and shape, and flow parameters such as mean velocity, fluctuant velocity and relative velocity between liquid and solid phase. The model was verified in the experiment of A356 alloys with a coaxial double-bucket rheometer. And the maximum relative error between the theoretical value and measured one is less than 20%. The results of experiment and theoretical calculation also indicate that the microstructural parameters and flow parameters are two major factors that affect the apparent viscosity of semi-solid alloys, and fluctuant velocity and relative velocity between liquid and solid phase are the key factors to distinguish between steady and transient rheological properties.
文摘The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results in this paper indicate that the viscous friction between semi-solid metal and pipe wall, the collisions among the solid particles, and the liquid flow around particles are the three main types of energy dissipation. On the basis of the hydromechanics, the energy dissipation calculation model is built. It is demonstrated that the micro-structural parameters such as effective solid fraction, particle size and shape, and flow parameters such as the mean velocity, the fluctuant velocity of particles and the relative velocity between the fluid and solid phase, affect the energy dissipation of semi-solid metal.
基金supported by the Fundamental Research Funds for the Central Universities(grant No.N180904007)the open funds of Key Laboratory of Electromagnetic Processing of Materials,Ministry of Education,Northeastern University(grant No.NEUEPM-014)。
文摘Accurate prediction of apparent viscosity and analyzing the influence mechanism of particle behavior on apparent viscosity is of great importance for the semi-solid processing process.In this paper,the coupled CFD-DEM method is employed to study the solid-liquid two phase flow and particle behavior in semisolid aluminum.The artificial neural networks method is used to predict the lubrication force range and calculate the apparent viscosity of semi-solid aluminum.The results show that the increasing shear rate results in the increasing coordination number of clusters,indicating that the spherical evolution of clusters caused by shear is important reason for the shear thinning of semi-solid metal.The blockage caused by the large cluster formed under high solid volume fraction leads in the high apparent viscosity.Predicting the apparent viscosity of semi-solid metal must consider the particle agglomeration behavior.Based on artificial neural networks method,the apparent viscosity of semi-solid metal can be estimated accurately by predicting the lubrication force range under different solid volume fractions and shear conditions.
基金funded by the National Natural Science Foundation of China(Project No.31471676)the National Key Research and Development Plan Sub-Topic(Project No.2016YFD040130301).
文摘Apparent viscosity is an important parameter for glucose syrup production.which is greatly affected by particle size and concentration of samples.In order to analyze the factors influencing the apparent viscosity,the particle size distribution,steady shear flow behavior,temperature,and time sweep test of native degerminated maize grits(NDMG),extruded degerminated maize grits(EDMG),and enzymatically extruded degerminated maize grits(EEDMG)with different particle sizes(passed through 20,40,60,80,and 100 mesh sieves)and concentrations(water-sample ratios:2:1,3:1,5:1,10:1,and 20:1)were investigated.All samples passed through different mesh sieves showed a gradient and a relatively concentrated distribution,and slurries had typical shear-thinning properties.Apparent viscosity increased with increasing particle size and concentration.The lowest apparent viscosity was attained from the samples obtained at 100+mesh and 20:1 water-sample ratio.Moreover,the sample with a 20:1 water-sample ratio showed the most stable apparent viscosity in the temperature sweep test.In the time sweep test,the power law equation with high determination coefficients(R^(2)=0.9446,0.9382)and low root mean square error(RMSE=0.0002)had the best fit to the experimental data of the EDMG and EEDMG samples passed through 100+mesh.Overall,the lower apparent viscosities of the EDMG and EEDMG samples obtained at 100+mesh and 20:1 water-sample ratio can improve the activity and accessibility of enzymes for glucose syrup production.This study provides critical insight into decreased apparent viscosity and expands the uses of EDMG and EEDMG in the glucose syrup sector.
基金supported by the National Natural Science Foundation of China(U1903132)the Graduate Researchand Innovation Projects of Jiangsu Province(KYCX21_2408).
文摘The apparent viscosity reflects the resistance of the fluidized medium in the bed to the beneficiation particles,which directly affects the separation time and mismatch content.So,the falling-ball method was used to measure the apparent viscosity of a binary medium in a pulsed fluidized bed by varying the gas velocity,pulsation frequency,and fine particle content.The results show that with increasing gas velocity and fine particle content,the apparent viscosity of the bed gradually decreased,whereas it first decreased and then increased with pulsation frequency increasing and achieved a minimum value in the range of 4-6 Hz.Within limits,the adjustment of gas velocity and fine content can effectively reduce the apparent viscosity and improve the separation process.A model for predicting the apparent viscosity in a pulsation separation fluidized bed was established with good accuracy.
文摘Being one of the most commonly performed EOR methods, polymer injection is used to increase themobility ratio and decrease water relative permeability to allow the injected fluid to sweep more oiltowards the production well. Before the polymer solution is injected into the reservoir through the injection wells, the process of polymer injection must be simulated using commercial numerical reservoirsimulators. In order to be able to simulate the process, the viscosity behavior of the solution must beknown. Therefore, a model is required to estimate the viscosity of the injected fluids versus shear rateand polymer concentration. In this study, a new mathematical function based on the power-law fluidequation is presented, which can be applied to predict the viscosity of SPAM solutions. The two requiredparameters of the power-law equation are obtained by fitting a power-law function to the viscosity-shearrate data. Samples in different polymer concentrations (using two SPAM polymers with different molecular weights) were prepared and their viscosity was measured against different shear rates. The results were fitted to the power-law equation and their corresponding power-law parameters wererecorded. A mathematical function was introduced and tested for each parameter. The new functionscombined with the power-law equation were used to estimate the viscosity of different polymer solutions with different SPAM concentrations. The results showed that the model is capable of estimating theviscosity with acceptable precision. Furthermore, it is applicable in various temperatures and watersalinities.
基金supported by the National Natural Science Foundation of China(grant No.52322405)the National Key R&D Program of China(grant No.2022YFC2905900)+2 种基金the Central Guidance on Local Science and Technology Development Fund of Xinjiang(grant No.ZYYD2024CG08)the Fundamental Research Funds for Central Universities(grant No.2023ZDPY07)Research Program of Jiangsu Key Laboratory for Clean Utilization of Carbon Resources(grant No.BM2024007).
文摘Efficient dry separation is essential for utilizing low-grade oil shale.This study developed a ternary high-density gas–solid fluidized bed system using ferrosilicon powder,magnetite powder,and D-class oil shale particles,focusing on the impact of apparent viscosity on particle settling.Results showed that viscosity was influenced by medium composition,particle size,and flow structure.In the binary system of B−silicon and B+magnetite,minimum viscosity(0.782 Pa s)was reached at a 40%ferrosilicon ratio.In the ternary system,viscosity increased nonlinearly with oil shale content,with 8%being the critical threshold where fluidization stability declined.Gas velocity significantly affected viscosity distribution,with moderate increases improving flow uniformity and reducing viscosity by 32%–40%.However,excessive velocity caused bubble coalescence and increased viscosity fluctuations,with standard deviation rising from 0.0065 to 0.0191 Pa s.Sedimentation tests showed that the middle bed region provided optimal separation at low gas velocity,while higher velocities shifted separation to the upper region.When gas velocity exceeds 0.45 m/s,the best separation efficiency is achieved.This study clarifies the relationship between viscosity and separation performance,providing guidance for optimizing dry oil shale separation.
基金the Ministry of Higher Education(Vot no.Q.J130000.2542.08H61)Universiti Teknologi(UTM)Malaysia,for supporting this research through research management grant
文摘Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent viscosity was also determined in Hele-Shaw cell In order to investigate the foam performance at static and dynamic conditions. Results show that the maximum adsorption of surfactant on the nanoparticles occurs at 3 wt% surfactant concentration. Foam stability increases while the foamability decreases with the increasing nanoparticle concentration. However, optimum nanoparticle concentration corresponding to maximum foam stability was obtained at 1.0 wt% nanoparticle concentration for the hydrophilic SiO_2/SDS and Al_2O_3/SDS foams. Foam performance was enhanced with increasing nanoparticles hydrophobicity. Air-foams were generally more stable than CO_2 foams.Foam apparent viscosity increased in the presence of nanoparticles from 20.34 mPa·s to 84.84 mPa·s while the film thickness increased from 27.5 μm to 136 μm. This study suggests that the static and dynamic stability of conventional foams could be improved with addition of appropriate concentration of nanoparticles into the surfactant solution. The nanoparticles improve foam stability by their adsorption and aggregation at the foam lamellae to increase film thickness and dilational viscoelasticity. This prevents liquid drainage and film thinning and improves foam stability both at the bulk and bubble scale.
基金financial support from the National Key Technology R&D Program in the 12th Five Year Plan of PetroChina (No: 2011ZX05010-003-02)the National Key Technology R&D Program in the 12th Five Year Plan of CNOOC (No: 2011ZX05024-04-05-03)
文摘Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr^3＋ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr^3＋, and a cross-linked polymer （CLP） system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity （namely storage modulus, loss modulus, and first normal stress difference） increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low- permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection （HPAM-1, Cr^3＋ as the cross linker） is 3.1% to 5.2% higher than that by HPAM- 2 injection.
基金financial support by Universiti Teknologi PETRONAS (No. YUTP-0153AA-E70)
文摘This paper presents the rheological behaviour of supercritical CO2 （sCO2） foam at reser- voir conditions of I 500 psi and 80 ℃. Different commercial surfactants were screened and utilized in or- der to generate a fairly stable CO2 foam. Mixed surfactant system was also introduced to generate strong foam. Foam rheology was studied for some specific foam qualities using a high pressure high tempera- ture （HPHT） foam loop rheometer. A typical shear thinning behaviour of the foam was observed and a significant increase in the foam viscosity was noticed with the increase of foam quality until 85%. A de- sired high apparent viscosity with coarse texture was found at 85% foam quality. Foam visualization above 85% showed an unstable foam due to extremely thin lamella which collapsed and totally disap- peared in the loop rheometer. Below 52%, a non-homogenous and unstable foam was found having low viscosity with some liquid accumulation at the bottom of the circulation loop. This research has demon- strated rheology of sCO2 foams at different qualities at HPHT to obtain optimal foam quality region for immiscible CO2 foam co-injection process.
基金supported by the National Natural Science Foundation of China (22078030, U1802255)National Key Research and Development Project (2019YFC1905802)+1 种基金Key Project of Independent Research Project of State Key Laboratory of Coal Mine Disaster Dynamics and Control (2011DA105287-zd201902)Three Gorges Laboratory Open Fund of Hubei Province (SK211009, SK215001)。
文摘The hydrodynamic performance of three mixers single shaft central mixer(SSC), single shaft off-centred mixer(SSO), dual shaft off-centred mixer(DSO), was investigated in the mixing of yield-pseudoplastic fluids(xanthan gum solutions) in the laminar regime. To explore and determine the efficiency of three mixers, both numerical and experimental approaches were adopted. The fluid rheology was described by the Herschel–Bulkley rheological model. Computational fluid dynamics was employed to simulate the apparent viscosity distribution, mixing time, and the flow pattern inside the stirred tank. The developed model was validated through experimentally measured torque. The influence mechanism of the rotational speed and fluid rheology on the cavern evolution was explored deeply. The performances of three mixers in this work were compared at the constant power input and fluid rheology with respect to the flow pattern, mixing time, and mixing efficiency. The results verify that the faster the rotating speed, the greater influence of the fluid rheology on the cavern evolution, and the more uniform apparent viscosity distribution. Moreover, the mixing time decreases continuously as the increasing power consumption per unit volume, and the dimensionless mixing time of DSO mixer was nearly 42.8% and 6.1% shorter than that of SSC and SCO mixer at the same Reynolds number, respectively. According to the mixing efficiency criteria, these data also revealed that DSO was more efficient than SSC and SSO.
基金supported by the National Basic Research Program of China(No.2011CB606302-1)the National Natural Science Foundation of China(No.51074024)
文摘The further application of semi-solid processing lies in the in-depth fundamental study like rheological behavior. In this research, the apparent viscosity of the semi-solid slurry of 7075 alloy was measured using a Couette type viscometer. The effects of solid fraction and shearing rate on the apparent viscosity of this alloy were investigated under different processing conditions. It can be seen that the apparent viscosity increases with an increase in the solid fraction from 10% to 50% （temperature 620 ℃ to 630 ℃） at steady state. When the solid fraction was fixed, the apparent viscosity can be decreased by altering the shearing rate from 61.235 s-1 to 489.88 s-1 at steady state. An empirical equation that shows the effects of solid fraction and shearing rate on the apparent viscosity is fitted： ηα = [0.871 - 0.00849. γ0.74924]. exp（3.7311, fs） . The microstructure of quenched samples was examined to understand the alloy＇s rheological behavior.
基金the Natural Science Foundation of Gansu Province （Grant No. ZS031-A25-29-C） the International Cooperation Item of China and New Zealand （Grant No. 2002DFG00020）.
文摘Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble-1500D simulator and the true stress-strain curves were given directly. The relationship of apparent viscosity vs temperature, shear rate and holding time of the three kinds of semi-solid magnesium alloys, as well as isothermal steady state rheological characteristic and mechanical behavior were studied. The results show that the three magnesium alloys had the characteristic of shear-thinning. The rheological characteristic of the semi-solid MB15 is different from that of semi-solid AZ91D. The semi-solid MB15 has higher apparent viscosity and deformation resistance.
基金the National Natural Science Foundation of China (No. 39770899)
文摘Objective: To study the effects of L.F04, the active fraction of Lycopus lucidus, on erythrocytes rheological property so as to investigate its mechanism in promoting blood circulation and removing blood stasis. Method: The effects of L.F04 (used for treatment for 10 days in different dosages) on deformability, aggregation and membrane liquidity of erythrocytes (MLE) as well as whole blood apparent viscosity (η_b) were examined on the basis of rat model of blood-stasis syndrome induced by venous injection of high molecular weight dextran. Result: As compared with the normal control group, the model group's RBC deformability and MLE were lower, and the aggregation of erythrocytes and η_b were higher. Compared with the model group, both L.F04 0.612g/kg and 0.306g/kg showed significant effect in improving deformability and inhibiting aggregation of red blood cells (RBC) and reducing blood viscosity. The trend of improving MLE was also shown. Conclusion: L.F04 could significantly improve the abnormal rheological property of erythrocytes.
基金financially supported by the National Natural Science Foundation of China (Nos.52104266 and 52074206)Open Foundation of State Key Laboratory of Mineral Processing (No.BGRIMM-KJSKL-2021-19)+2 种基金the Natural Science Basic Research Program of Shaanxi Province (No.2021JQ-507)the Natural Science Project of Shaanxi Education Department (No.21JK0731)Key Research and Development Projects of Anhui Province (No.202104a07020012)。
文摘The flotation separation of chalcopyrite and talc is challenging due to their similar natural floatability characteristics.Besides,it is usually difficult to effectively inhibit talc by adding sodium carboxymethyl cellulose(CMC)alone during chalcopyrite flotation.Here,a combined inhibitor comprising acidified sodium silicate(ASS)and CMC was employed to realize effective flotation separation of chalcopyrite and talc,and the combined inhibition mechanism was further investigated.Microflotation results showed that adding ASS strengthened the inhibitory effect of CMC on talc and improved the separation of chalcopyrite and talc.The zeta potential,Fourier transform infrared,and X-ray photoelectron spectroscopy analysis indicated that CMC was mainly adsorbed on the talc surface via hydroxyl and carboxyl groups.Moreover,the addition of ASS improved the adsorption of carboxyl groups.Furthermore,the adsorption experiments and apparent viscosity measurements revealed that adding ASS dispersed the pulp well,which reduced the apparent viscosity,improved the adsorption amount of CMC on the talc surface,and enhanced the inhibition of talc in chalcopyrite flotation.
基金financially supported by the National Natural Science Foundation of China (Nos.51364035 and 51165032)
文摘The rheological behavior of semisolid Mg_(2)Si/AM60 composites prepared by ultrasonic vibration treatment was investigated.The effects of primaryα-Mg solid content,the ultrasonic power and the content of reinforcement phase Mg_(2)Si on the apparent viscosity of semisolid composites were discussed.The results show that the apparent viscosity of the semis olid composites increases with the increase in a-Mg solid content.Meanwhile,the apparent viscosity decreases with the increase in ultrasonic power,and the reduction amplitude is higher when the solid content is higher.In addition,the apparent viscosity increases with the increase in Mg_(2)Si content.Based on experimental data fitting,the rheological model of semisolid Mg_(2)Si/AM60 composites prepared by ultrasonic vibration was established.
基金Funded by the Innovative Group of Science and Technology of College of Jiangxi Province(No.00008713)
文摘The rheological behavior of semi-solid AZ91D magnesium alloy was investigated in isothermal steady state condition. The effects of stirring temperature and shearing rate on apparent viscosity of semi-solid alloy slurry at steady state were discussed. The results show that the apparent viscosity of semisolid AZ91D alloy increases with increasing solid fraction. It increases slightly before the solid fraction reaches a certain value, about 0.4, and then goes up rapidly aider the solid fraction reaches the critical value. However, the apparent viscosity decreases with increasing shearing rate, and the reduction amplitude is higher when the solid fraction is higher. According to the experimental data, an empirical equation that shows the effect of solid fraction and sheafing rate on the apparent viscosity of semi-solid AZ91D alloy can be built as ηa=9.7×10^-2 exp（13.87fs）γ^-0.58.
基金the sponsor CSIR (Council of Scientific and Industrial Research), New Delhi for their financial grant to carry out the present research work
文摘Detailed experimental investigations were carried out for microwave pre-treatment of high ash Indian coal at high power level(900 W) in microwave oven. The microwave exposure times were fixed at60 s and 120 s. A rheology characteristic for microwave pre-treatment of coal-water slurry(CWS) was performed in an online Bohlin viscometer. The non-Newtonian character of the slurry follows the rheological model of Ostwald de Waele. The values of n and k vary from 0.31 to 0.64 and 0.19 to 0.81 Pa·sn,respectively. This paper presents an artificial neural network(ANN) model to predict the effects of operational parameters on apparent viscosity of CWS. A 4-2-1 topology with Levenberg-Marquardt training algorithm(trainlm) was selected as the controlled ANN. Mean squared error(MSE) of 0.002 and coefficient of multiple determinations(R^2) of 0.99 were obtained for the outperforming model. The promising values of correlation coefficient further confirm the robustness and satisfactory performance of the proposed ANN model.
基金The work is supported by Foundation for University Key Teacher by the Ministry of Education, Jiangxi Foundation of Natural Science (Grant No. 0050034)and Nan-chang University Foundation, respectively.
文摘Under the condition of die casting and reheating temperature of 570-580 degC, the rheological behavior of semi-solid aluminum alloy (A356) is pseudoplasticity at the shearrate of 2X10^-1X10^4s^(-1), and also shows dilatancy at the rate over 10~6s^(-1).
