The hydrodynamics of the capillary flow of a viscous-plastic liquid in cylindrical rectilinear pores is considered, as a result of which the structural velocity distribution over the pore cross section is obtained. An...The hydrodynamics of the capillary flow of a viscous-plastic liquid in cylindrical rectilinear pores is considered, as a result of which the structural velocity distribution over the pore cross section is obtained. Analytical solutions are proposed for the equations of hydraulic diffusion and nonlinear filtration for a non-Newtonian fluid in a cylindrical porous medium. It is noted that when a non-Newtonian fluid flows in a porous medium, the filtration equations take a nonlinear form due to the effective viscosity, shear, and yield stresses taken into account in its structure. The proposed solutions make it possible to evaluate the state of the porous medium and its main parameters (permeability, hydraulic diffusion, and effective viscosity coefficients). The obtained solutions are compared with existing experimental data for non-Newtonian oils.展开更多
The rapeseed oil extracted from the mature seeds was purified by refining processing,and the rheological characteristic analysis of the viscosity and dynamic shear rate at gradient temperatures was made.The result sho...The rapeseed oil extracted from the mature seeds was purified by refining processing,and the rheological characteristic analysis of the viscosity and dynamic shear rate at gradient temperatures was made.The result shows that at 20,40,60 and 80 ℃ respectively,when the shear rate gradually rises,the torque increases accordingly but its viscosity does not vary distinctly.The result suggests that when rapeseed oil is used as the raw of edible oils and industries,the working procedures at high temperature will not influence its rheological characteristic distinctly.展开更多
The sinkage of a moving tracked mining vehicle is greatly af fected by the combined compression-shear rheological properties of soft deep-sea sediments. For test purposes, the best sediment simulant is prepared based ...The sinkage of a moving tracked mining vehicle is greatly af fected by the combined compression-shear rheological properties of soft deep-sea sediments. For test purposes, the best sediment simulant is prepared based on soft deep-sea sediment from a C-C poly-metallic nodule mining area in the Pacific Ocean. Compressive creep tests and shear creep tests are combined to obtain compressive and shear rheological parameters to establish a combined compressive-shear rheological constitutive model and a compression-sinkage rheological constitutive model. The combined compression-shear rheological sinkage of the tracked mining vehicle at dif ferent speeds is calculated using the Recur Dyn software with a selfprogrammed subroutine to implement the combined compression-shear rheological constitutive model. The model results are compared with shear rheological sinkage and ordinary sinkage(without consideration of rheological properties). These results show that the combined compression-shear rheological constitutive model must be taken into account when calculating the sinkage of a tracked mining vehicle. The combined compression-shear rheological sinkage decrease with vehicle speed and is the largest among the three types of sinkage. The developed subroutine in the Recur Dyn software can be used to study the performance and structural optimization of moving tracked mining vehicles.展开更多
Methylene bis(thiocyanate)(MBT) is insoluble in water, so suspension concentrate(SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of sur...Methylene bis(thiocyanate)(MBT) is insoluble in water, so suspension concentrate(SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of surfactants,such as Morwet D425(D425) and Morwet EFW(EFW)(two kinds of dispersant), on the Zeta potential and rheology behavior of MBT SC were investigated. The results showed that the Zeta potential absolute value of MBT SC increased with the increasing content of D425, and it decreased with the increasing content of EFW at acidic solution(pH = 4.5). In the combination system of D425 and EFW, Zeta potential of MBT SC decreased first and then increased with the increasing content of EFW. The relationship between shear rate(γ) and viscosity(η) was studied according to Herschel–Bulkley model: η = η0+ k/γ, and the relationship between shear rate(γ) and shear force(τ) was investigated according to:τ = τ0+Kγ~n. It was revealed that the mixed fluid belonged to Yield Pseudoplastic Fluid.展开更多
The rheological analysis on dynamic shear rate-viscosity relationship of tea-oil extracted from tea-oil tree seeds by supercritical extraction method was carried out at gradient temperatures and constant shear rate,re...The rheological analysis on dynamic shear rate-viscosity relationship of tea-oil extracted from tea-oil tree seeds by supercritical extraction method was carried out at gradient temperatures and constant shear rate,respectively.The results show that at 20,40,60 and 80 ℃,once the shear rate increases gradually,the torque enlarges correspondingly,while the viscosity shows little difference.However,at the constant shear rate,the rising temperature results in a steady downtrend on tea-oil viscosity.This results reveal that tea-oil viscosity is not closely correlated with shear rate at constant temperature,yet negatively correlated with temperature at constant shear rate.展开更多
The rheological behavior of the semi-solid Ti B2 reinforced Al-Mg alloy composite slurry was investigated,which is required for the mould filling simulations during the semi-solid processing.Ti B2 reinforced in-situ A...The rheological behavior of the semi-solid Ti B2 reinforced Al-Mg alloy composite slurry was investigated,which is required for the mould filling simulations during the semi-solid processing.Ti B2 reinforced in-situ Al-Mg alloy composite samples were remelted and subsequently brought to the semi-solid temperature regime within the heating chamber of a Searle type rheometer.In order to understand the rheological behavior of composites,three different types of experiment were carried out,namely,steady state test,continuous cooling test and isothermal test.Apart from that,the thixotropic nature of the slurry was confirmed from the obtained hysteresis loops during the experimentation.The results indicate that when isothermally held,the composite slurry exhibits pseudo-plasticity and shows shear-thinning behavior up to the shear rate of 1300 s^-1,and at higher shear rates（1300 s^-1）,it shows a shear thickening tendency,which is probably due to the agglomeration of non-deformable nano-Ti B2 particles.The pseudo-plastic behavior of the slurry was also estimated employing intermittent step changes of shear rate（shear jump test）.展开更多
Rheological characterization of tomato products is important not only for design of unit operations, but also to optimizeprocesses and guarantee high quality of food products. Time dependence is related with structura...Rheological characterization of tomato products is important not only for design of unit operations, but also to optimizeprocesses and guarantee high quality of food products. Time dependence is related with structural changes due to shear rate. Thus,rheological characterization as a function of time is extremely important to understand the changes that occurred in food productsduring commercial processes. However, these characterizations are rare in the literature for tomato products. Those rheologicalproperties depend of several parameters, such as agronomic, structural and process parameters. In this study, the effect of shear rateon the viscosity at room temperature （22 ~C） of two kinds of tomato sauce （homemade and commercial） is analyzed; using aBrookfield viscometer model 4535, Lab-Line Instruments. Homemade sauce was prepared with fresh saladette tomatoes from a localmarket. Rheological analysis was performed at shear rates from 0.05 to 10.47 sl; using all the spindles available. Statistical analysiswas made using LSD and Duncan tests with a confidence interval of 95% （p-value of 0.05）. It was demonstrated that homemade andcommercial tomato sauce behaved as a thixotropic fluid, due to the typical decrease on viscosity samples observed when testing timewas increased. When tomato sauce is at rest, it has a gelled tridimensional structure; and, as soon as a shear stress is applied, themovement generates an alignment of tomato constituent chains in flow direction, breaking physic entanglements and thus causing adecrease in viscosity as a function of time. Furthermore, it was discovered that the viscosity of homemade sauce was higher than theviscosity of commercial sauce. The latter may be due to the pre-thermal treatment. During this unit operation, polymeric chains oflycopene most likely break into smaller chains of isoprene, causing the observed decrease in viscosity. Besides, commercial saucecontains additives, seasonings, preservatives and thickeners that are not in a homemade sauce.展开更多
The main objective of this study was the analysis of physicochemical and rheological behavior of a drinkable beverage prepared with different concentrations (5%, 10% and 20% w/w) of Kefir. Several rheological models w...The main objective of this study was the analysis of physicochemical and rheological behavior of a drinkable beverage prepared with different concentrations (5%, 10% and 20% w/w) of Kefir. Several rheological models were also evaluated to determine the model that better fit experimental data. Apparent viscosity was measured with a Brookfield Viscometer within shear rates of 0.26 rad/s to 2.09 rad/s; and with an Ar-2000ex TA Instruments Rheometer within shear rates of 0.01 rad/s to 1,000 rad/s. Physicochemical tests, such as titratable acidity, chloride percent, fat concentration, color, humidity, syneresis, and total solids, were determined using laboratory equipment. The main result observed in all samples tested with Brookfield viscometer was that Kefir drink behaved as a Newtonian Fluid within shorter strain rates (0.26 rad/s to 2.09 rad/s). However, when the same samples were tested with Ar-2000ex Rheometer, a different behavior was observed: Over a wider range of shear rates, the fully non-Newtonian behavior of Kefir samples was discovered. Besides, additional variables such as shear and normal stresses, and loss and storage modulus, were analyzed with Ar-2000ex Rheometer. The rheological model that better fitted the experimental data was Cross model, followed by Power Law Model. Statistical analysis of viscosity data acquired with Brookfield Viscometer from all Kefir concentrations was not significant (p values greater than 0.05); which demonstrated that the effect of Kefir concentration over shorter strain rates was not significant, and thus, the samples behave as a Newtonian fluid. On the other hand, p values lower than 0.05 were observed in most of the different Kefir concentration samples tested with Ar-2000ex Rheometer; which indicates that a statistical significant effect was observed and thus a non-Newtonian behavior of Kefir samples. All statistical analysis was performed with SPSS v.16 software, selecting a Duncan Test with a confident interval of 95% to accept or reject the variances compared of the different Kefir concentration samples.展开更多
文摘The hydrodynamics of the capillary flow of a viscous-plastic liquid in cylindrical rectilinear pores is considered, as a result of which the structural velocity distribution over the pore cross section is obtained. Analytical solutions are proposed for the equations of hydraulic diffusion and nonlinear filtration for a non-Newtonian fluid in a cylindrical porous medium. It is noted that when a non-Newtonian fluid flows in a porous medium, the filtration equations take a nonlinear form due to the effective viscosity, shear, and yield stresses taken into account in its structure. The proposed solutions make it possible to evaluate the state of the porous medium and its main parameters (permeability, hydraulic diffusion, and effective viscosity coefficients). The obtained solutions are compared with existing experimental data for non-Newtonian oils.
基金Project(2007CB210201) supported by Major State Basic Research Development Program of ChinaProject(07JJ6053) supported by Hunan Provincial Natural Science Foundation of China
文摘The rapeseed oil extracted from the mature seeds was purified by refining processing,and the rheological characteristic analysis of the viscosity and dynamic shear rate at gradient temperatures was made.The result shows that at 20,40,60 and 80 ℃ respectively,when the shear rate gradually rises,the torque increases accordingly but its viscosity does not vary distinctly.The result suggests that when rapeseed oil is used as the raw of edible oils and industries,the working procedures at high temperature will not influence its rheological characteristic distinctly.
基金Supported by the National Natural Science Foundation of China(Nos.51274251,11502226)
文摘The sinkage of a moving tracked mining vehicle is greatly af fected by the combined compression-shear rheological properties of soft deep-sea sediments. For test purposes, the best sediment simulant is prepared based on soft deep-sea sediment from a C-C poly-metallic nodule mining area in the Pacific Ocean. Compressive creep tests and shear creep tests are combined to obtain compressive and shear rheological parameters to establish a combined compressive-shear rheological constitutive model and a compression-sinkage rheological constitutive model. The combined compression-shear rheological sinkage of the tracked mining vehicle at dif ferent speeds is calculated using the Recur Dyn software with a selfprogrammed subroutine to implement the combined compression-shear rheological constitutive model. The model results are compared with shear rheological sinkage and ordinary sinkage(without consideration of rheological properties). These results show that the combined compression-shear rheological constitutive model must be taken into account when calculating the sinkage of a tracked mining vehicle. The combined compression-shear rheological sinkage decrease with vehicle speed and is the largest among the three types of sinkage. The developed subroutine in the Recur Dyn software can be used to study the performance and structural optimization of moving tracked mining vehicles.
基金Supported by Guangzhou Science Technology and Innovation Commission(201508030019)China Scholarship Council(201506155073)National Undergraduate Innovative and Entrepreneurial Training Program(201610561089)
文摘Methylene bis(thiocyanate)(MBT) is insoluble in water, so suspension concentrate(SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of surfactants,such as Morwet D425(D425) and Morwet EFW(EFW)(two kinds of dispersant), on the Zeta potential and rheology behavior of MBT SC were investigated. The results showed that the Zeta potential absolute value of MBT SC increased with the increasing content of D425, and it decreased with the increasing content of EFW at acidic solution(pH = 4.5). In the combination system of D425 and EFW, Zeta potential of MBT SC decreased first and then increased with the increasing content of EFW. The relationship between shear rate(γ) and viscosity(η) was studied according to Herschel–Bulkley model: η = η0+ k/γ, and the relationship between shear rate(γ) and shear force(τ) was investigated according to:τ = τ0+Kγ~n. It was revealed that the mixed fluid belonged to Yield Pseudoplastic Fluid.
基金Projects(2007CB210201) supported by the Major State Basic Research Development Program of China
文摘The rheological analysis on dynamic shear rate-viscosity relationship of tea-oil extracted from tea-oil tree seeds by supercritical extraction method was carried out at gradient temperatures and constant shear rate,respectively.The results show that at 20,40,60 and 80 ℃,once the shear rate increases gradually,the torque enlarges correspondingly,while the viscosity shows little difference.However,at the constant shear rate,the rising temperature results in a steady downtrend on tea-oil viscosity.This results reveal that tea-oil viscosity is not closely correlated with shear rate at constant temperature,yet negatively correlated with temperature at constant shear rate.
文摘The rheological behavior of the semi-solid Ti B2 reinforced Al-Mg alloy composite slurry was investigated,which is required for the mould filling simulations during the semi-solid processing.Ti B2 reinforced in-situ Al-Mg alloy composite samples were remelted and subsequently brought to the semi-solid temperature regime within the heating chamber of a Searle type rheometer.In order to understand the rheological behavior of composites,three different types of experiment were carried out,namely,steady state test,continuous cooling test and isothermal test.Apart from that,the thixotropic nature of the slurry was confirmed from the obtained hysteresis loops during the experimentation.The results indicate that when isothermally held,the composite slurry exhibits pseudo-plasticity and shows shear-thinning behavior up to the shear rate of 1300 s^-1,and at higher shear rates（1300 s^-1）,it shows a shear thickening tendency,which is probably due to the agglomeration of non-deformable nano-Ti B2 particles.The pseudo-plastic behavior of the slurry was also estimated employing intermittent step changes of shear rate（shear jump test）.
文摘Rheological characterization of tomato products is important not only for design of unit operations, but also to optimizeprocesses and guarantee high quality of food products. Time dependence is related with structural changes due to shear rate. Thus,rheological characterization as a function of time is extremely important to understand the changes that occurred in food productsduring commercial processes. However, these characterizations are rare in the literature for tomato products. Those rheologicalproperties depend of several parameters, such as agronomic, structural and process parameters. In this study, the effect of shear rateon the viscosity at room temperature （22 ~C） of two kinds of tomato sauce （homemade and commercial） is analyzed; using aBrookfield viscometer model 4535, Lab-Line Instruments. Homemade sauce was prepared with fresh saladette tomatoes from a localmarket. Rheological analysis was performed at shear rates from 0.05 to 10.47 sl; using all the spindles available. Statistical analysiswas made using LSD and Duncan tests with a confidence interval of 95% （p-value of 0.05）. It was demonstrated that homemade andcommercial tomato sauce behaved as a thixotropic fluid, due to the typical decrease on viscosity samples observed when testing timewas increased. When tomato sauce is at rest, it has a gelled tridimensional structure; and, as soon as a shear stress is applied, themovement generates an alignment of tomato constituent chains in flow direction, breaking physic entanglements and thus causing adecrease in viscosity as a function of time. Furthermore, it was discovered that the viscosity of homemade sauce was higher than theviscosity of commercial sauce. The latter may be due to the pre-thermal treatment. During this unit operation, polymeric chains oflycopene most likely break into smaller chains of isoprene, causing the observed decrease in viscosity. Besides, commercial saucecontains additives, seasonings, preservatives and thickeners that are not in a homemade sauce.
文摘The main objective of this study was the analysis of physicochemical and rheological behavior of a drinkable beverage prepared with different concentrations (5%, 10% and 20% w/w) of Kefir. Several rheological models were also evaluated to determine the model that better fit experimental data. Apparent viscosity was measured with a Brookfield Viscometer within shear rates of 0.26 rad/s to 2.09 rad/s; and with an Ar-2000ex TA Instruments Rheometer within shear rates of 0.01 rad/s to 1,000 rad/s. Physicochemical tests, such as titratable acidity, chloride percent, fat concentration, color, humidity, syneresis, and total solids, were determined using laboratory equipment. The main result observed in all samples tested with Brookfield viscometer was that Kefir drink behaved as a Newtonian Fluid within shorter strain rates (0.26 rad/s to 2.09 rad/s). However, when the same samples were tested with Ar-2000ex Rheometer, a different behavior was observed: Over a wider range of shear rates, the fully non-Newtonian behavior of Kefir samples was discovered. Besides, additional variables such as shear and normal stresses, and loss and storage modulus, were analyzed with Ar-2000ex Rheometer. The rheological model that better fitted the experimental data was Cross model, followed by Power Law Model. Statistical analysis of viscosity data acquired with Brookfield Viscometer from all Kefir concentrations was not significant (p values greater than 0.05); which demonstrated that the effect of Kefir concentration over shorter strain rates was not significant, and thus, the samples behave as a Newtonian fluid. On the other hand, p values lower than 0.05 were observed in most of the different Kefir concentration samples tested with Ar-2000ex Rheometer; which indicates that a statistical significant effect was observed and thus a non-Newtonian behavior of Kefir samples. All statistical analysis was performed with SPSS v.16 software, selecting a Duncan Test with a confident interval of 95% to accept or reject the variances compared of the different Kefir concentration samples.
