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
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 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 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
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
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
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 oC to 630 oC) at steady state. When the solid fraction was fi xed, 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 fi tted:. The microstructure of quenched samples was examined to understand the alloy's rheological behavior.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
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
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
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
Lauryl betaine(LB)as an amphoteric surfactant carries both positive and negative charges and should be able to generate stable foam through electrostatic interaction with nanoparticles and co-surfactants.However,no pr...Lauryl betaine(LB)as an amphoteric surfactant carries both positive and negative charges and should be able to generate stable foam through electrostatic interaction with nanoparticles and co-surfactants.However,no previous attempts have been made to investigate the influence of nanoparticles and other co-surfactants on the stability and apparent viscosity of LBstabilized foam.In this study,a thorough investigation on the influence of silicon dioxide(SiO2)nanoparticles,alpha olefin sulfonate(AOS)and sodium dodecyl sulfate(SDS),on foam stability and apparent viscosity was carried out.The experiments were conducted with the 2D Hele-Shaw cell at high foam qualities(80%-98%).Influence of AOS on the interaction between the LB foam and oil was also investigated.Results showed that the SiO2-LB foam apparent viscosity decreased with increasing surfactant concentration from 0.1 wt%to 0.3 wt%.0.1 wt%SiO2 was the optimum concentration and increased the 0.1 wt%LB foam stability by 108.65%at 96%foam quality.In the presence of co-surfactants,the most stable foam,with the highest apparent viscosity,was generated by AOS/LB solution at a ratio of 9:1.The emulsified crude oil did not imbibe into AOS-LB foam lamellae.Instead,oil was redirected into the plateau borders where the accumulated oil drops delayed the rate of film thinning,bubble coalescence and coarsening.展开更多
Kaolinite,as a mineral in fine coal,has an important influence on the flotation of coal particles.In this study,the effects of ultrafine kaolinite particles on the flotation recovery of coal particles were investigate...Kaolinite,as a mineral in fine coal,has an important influence on the flotation of coal particles.In this study,the effects of ultrafine kaolinite particles on the flotation recovery of coal particles were investigated.Flotation tests were carried out using a mixture of coal particles and different amounts of ultrafine kaolinite particles.Combined with the Stefan–Reynold theory,the effect of liquid film drainage rate between coal bubbles in a kaolinite suspension was calculated.The yield of flotation clean coal increases quickly with the increasing content of ultrafine kaolinite particles.The ultrafine kaolinite particles can reduce the surface tension of the suspension,weaken the bubble coalescence,and stabilize the structure of the froth layer.In addition,the ultrafine kaolinite particles increase the apparent viscosity of the flotation pulp slightly.It is concluded that the role of ultrafine kaolinite particles on the positive effect of froth properties conceals the negative effect on the liquid film drainage rate between coal particles and bubbles caused by the kaolinite particles,which ultimately leads to an increasing yield of clean coal with an increasing content of kaolinite particles.This study is important for understanding the influence of ultrafine kaolinite on coal particle flotation.展开更多
Influences of different superplasticizers ( STP. KSJSTO and LMS-P) on rheological behavior of low-cement castables and the mechanisms were analyzed. The shear stress and viscosity under different shear rates of matr...Influences of different superplasticizers ( STP. KSJSTO and LMS-P) on rheological behavior of low-cement castables and the mechanisms were analyzed. The shear stress and viscosity under different shear rates of matrix slurry were determined using a NXS-I IA rotary viscometer. Effects of different admixtures on the rheological properties of slurry was analyzed theoretically. Sodium tripolyphosphate and poly'carboxylate superplasticizers KS-JSTO and LMS-P) can improve the fluidity and initial setting time. With STP. the slurry is plastic flow. With KS-JS70 or LMS-P increasing, the slurrv changes from plastic.flow, pseudoplastic flow to dilatant flow successively. Th, e optimum dosages of STP. KS-JSTO and LMS-P are 0. 15%. 0. 25% and 0. 40%, respectively. KS-JS70 and LMS-P can significantly reduce the slurry viscosity and shear stress to improve the workability of construction. Both shear stress and viscosity shall be taken into account for on-site construction.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
Based on the dynamic triaxial liquefaction test of the loess samples which are taken from Shibei tableland,Guyuan City,Ningxia,China,the characteristics of dynamic strain,dynamic stress and pore water pressure are stu...Based on the dynamic triaxial liquefaction test of the loess samples which are taken from Shibei tableland,Guyuan City,Ningxia,China,the characteristics of dynamic strain,dynamic stress and pore water pressure are studied under cyclic loading.Triaxial shear test is conducted immediately after the sample reaches liquefaction point.During the test,the property of the liquefied soil is analyzed through fluid mechanics method,whereby the fluidity of the liquefied soil is represented by apparent viscosity.The results show that the fluidity of liquefied loess changes from“shear thickening”to“shear thinning”as the shear force continues,and the fluidity of liquefied loess is closely related to its structure.In addition,in the process of forming a new stable state,the apparent viscosity and deviant stress change with axial strain in a similar approach.When the sample reaches its stable state,it meanwhile shows a relatively stable apparent viscosity.According to the fluid mechanics and the law of conservation of energy,the slip distance of the liquefied soil is estimated,and the results are in good agreement with the field investigation results.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 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
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.
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 (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 oC to 630 oC) at steady state. When the solid fraction was fi xed, 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 fi tted:. The microstructure of quenched samples was examined to understand the alloy's rheological behavior.
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).
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Lauryl betaine(LB)as an amphoteric surfactant carries both positive and negative charges and should be able to generate stable foam through electrostatic interaction with nanoparticles and co-surfactants.However,no previous attempts have been made to investigate the influence of nanoparticles and other co-surfactants on the stability and apparent viscosity of LBstabilized foam.In this study,a thorough investigation on the influence of silicon dioxide(SiO2)nanoparticles,alpha olefin sulfonate(AOS)and sodium dodecyl sulfate(SDS),on foam stability and apparent viscosity was carried out.The experiments were conducted with the 2D Hele-Shaw cell at high foam qualities(80%-98%).Influence of AOS on the interaction between the LB foam and oil was also investigated.Results showed that the SiO2-LB foam apparent viscosity decreased with increasing surfactant concentration from 0.1 wt%to 0.3 wt%.0.1 wt%SiO2 was the optimum concentration and increased the 0.1 wt%LB foam stability by 108.65%at 96%foam quality.In the presence of co-surfactants,the most stable foam,with the highest apparent viscosity,was generated by AOS/LB solution at a ratio of 9:1.The emulsified crude oil did not imbibe into AOS-LB foam lamellae.Instead,oil was redirected into the plateau borders where the accumulated oil drops delayed the rate of film thinning,bubble coalescence and coarsening.
文摘Kaolinite,as a mineral in fine coal,has an important influence on the flotation of coal particles.In this study,the effects of ultrafine kaolinite particles on the flotation recovery of coal particles were investigated.Flotation tests were carried out using a mixture of coal particles and different amounts of ultrafine kaolinite particles.Combined with the Stefan–Reynold theory,the effect of liquid film drainage rate between coal bubbles in a kaolinite suspension was calculated.The yield of flotation clean coal increases quickly with the increasing content of ultrafine kaolinite particles.The ultrafine kaolinite particles can reduce the surface tension of the suspension,weaken the bubble coalescence,and stabilize the structure of the froth layer.In addition,the ultrafine kaolinite particles increase the apparent viscosity of the flotation pulp slightly.It is concluded that the role of ultrafine kaolinite particles on the positive effect of froth properties conceals the negative effect on the liquid film drainage rate between coal particles and bubbles caused by the kaolinite particles,which ultimately leads to an increasing yield of clean coal with an increasing content of kaolinite particles.This study is important for understanding the influence of ultrafine kaolinite on coal particle flotation.
文摘Influences of different superplasticizers ( STP. KSJSTO and LMS-P) on rheological behavior of low-cement castables and the mechanisms were analyzed. The shear stress and viscosity under different shear rates of matrix slurry were determined using a NXS-I IA rotary viscometer. Effects of different admixtures on the rheological properties of slurry was analyzed theoretically. Sodium tripolyphosphate and poly'carboxylate superplasticizers KS-JSTO and LMS-P) can improve the fluidity and initial setting time. With STP. the slurry is plastic flow. With KS-JS70 or LMS-P increasing, the slurrv changes from plastic.flow, pseudoplastic flow to dilatant flow successively. Th, e optimum dosages of STP. KS-JSTO and LMS-P are 0. 15%. 0. 25% and 0. 40%, respectively. KS-JS70 and LMS-P can significantly reduce the slurry viscosity and shear stress to improve the workability of construction. Both shear stress and viscosity shall be taken into account for on-site construction.
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Received on July 6th,2020revised on September 14th,2020.This project is sponsored by the National Natural Science Foundation of China(U1939209,51778590)the Spark Program(XH20057).
文摘Based on the dynamic triaxial liquefaction test of the loess samples which are taken from Shibei tableland,Guyuan City,Ningxia,China,the characteristics of dynamic strain,dynamic stress and pore water pressure are studied under cyclic loading.Triaxial shear test is conducted immediately after the sample reaches liquefaction point.During the test,the property of the liquefied soil is analyzed through fluid mechanics method,whereby the fluidity of the liquefied soil is represented by apparent viscosity.The results show that the fluidity of liquefied loess changes from“shear thickening”to“shear thinning”as the shear force continues,and the fluidity of liquefied loess is closely related to its structure.In addition,in the process of forming a new stable state,the apparent viscosity and deviant stress change with axial strain in a similar approach.When the sample reaches its stable state,it meanwhile shows a relatively stable apparent viscosity.According to the fluid mechanics and the law of conservation of energy,the slip distance of the liquefied soil is estimated,and the results are in good agreement with the field investigation results.
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.