A NEW TYPE LOW SHEAR RATE VISCOMETER FOR HIGH MOLECULAR WEIGHT POLYMER

In this paper, the effects of shear rate on the intrinsic viscosity measurement of partially Hydrolysed Polyacrylamide (HPAM) in salt solution were studied with homemade multibulb viscometer and low shear rate rheometer. The critical shear rate of HPAM in salt solution for high molecular weight HPAM was determined. A low shear rate capillary viscometer was designed in which the [eta] approached to value at zero shear rate can be obtained for HPAM -salt system. The effect of molecular weight on shear rate dependence of viscosity was also studied.

Effect of Thermal Convection on Viscosity Measurement in Vibrational Viscometer

This paper describes the experimental study of viscosity measurement error in the vibrational type viscometer, which measures viscous damping of the oscillating circular plate in a fluid in continuously increasing temperatures. The experiments are carried out to measure non-uniformity of the temperature field in the test cup of the vibrational viscometer in continuously increasing temperatures, while changing the viscosity of the target fluids. Experimental outcomes show that non-uniformity of the temperature grows in the cup and results in viscosity measurement error, when the viscosity of the fluid increases. In order to understand this phenomenon, velocity measurement by particle image velocimetry is conducted in the test cup for fluids of varying viscosity. The results indicate that mixing is enhanced in the low-viscosity fluid by the occurrence of unsteady thermal convection, while weaker convection appears in the high-viscosity fluid.

Ultra-High Sensitivity Viscometer Based on a Torsion Pendulum

Based on a conventional torsion pendulum,we develop a forced oscillation viscometer with ultra-high viscosity sensitivity of 2×10^（-7）Pa·s working at frequencies near the resonance.The viscosity is achieved by exploiting the phase lag for the angle displacement behind the torque,instead of the resonant curve,i.e.,the variation of angle displacement amplitude versus frequency.The general formula for the measurement of the visco-elasticit.y of complex fluids is also presented.With such precision it is easy to measure tiny change in viscosity result from circumstantial influences.Deionized water and two kinds of NaCl aqueous solutions are chosen to demonstrate the performance of our home-made torsion pendulum-based viscometer.

THE APPARENT VISCOSITY OF SEMI-SOLID AZ91D ALLOY AT STEADY STATE

The rheological behavior of semi-solid AZ91D at steady state is studied usinga Couette type viscometer in the present paper. The results show that the apparent viscosity ofsemi-solid AZ91D at the steady state increases with the solid fraction increasing, and goes upsharply when the solid fraction reaches a certain value, which is called critical fraction. Inaddition, the apparent viscosity of semi-solid AZ91D at the steady state takes on a distinctdowntrend with the shearing rate increasing, which indicates a strong shear thinning property. Inaddition, the critical solid fraction becomes higher under larger shearing rate, owing to the moreglobular shape of the solid particles. Based on the present experiment results, an empiricalequation is built as that, relating the steady state apparent viscosity of semi-solid AZ91D with thesolid fraction f_s and shearing rate gamma at the same time: eta_(app)=10.74 exp (6.95 f_s)gamma^(-0.86).

A new and reliable model for predicting methane viscosity at high pressures and high temperatures

In recent years, there has been an increase of interest in the flow of gases at relatively high pressures and high temperatures. Hydrodynamic calculation of the energy losses in the flow of gases in conduits, as well as through the porous media constituting natural petroleum reservoirs, requires knowledge of the viscosity of the fluid at the pressure and temperature involved. Although there are numerous publications concerning the viscosity of methane at atmospheric pressure, there appears to be little information available relating to the effect of pressure and temperature upon the viscosity. A survey of the literature reveals that the disagreements between published data on the viscosity of methane are common and that most investigations have been conducted over restricted temperature and pressure ranges. Experimental viscosity data for methane are presented for temperatures from 320 to 400 K and pressures from 3000 to 140000 kPa by using falling body viscometer. A summary is given to evaluate the available data for methane, and a comparison is presented for that data common to the experimental range reported in this paper. A new and reliable correlation for methane gas viscosity is presented. Predicted values are given for temperatures up to 400 K and pressures up to 140000 kPa with Average Absolute Percent Relative Error （EABS） of 0.794.

Experimental Investigation on Viscosity of Cu-H_2O Nanofluids

A procedure for preparing a nanofluid that a solid-liquid composite material consists of solid nanoparticles with sizes typically of 1-100 nm suspended in liquid was proposed. By means of the procedure, Cu-H2O nanofluids with and without dispersant were prepared, whose sediment pho-tographs and particle size distribution were given to illustrate the stability and evenness of suspension with dispersant. The viscosity of Cu-H2O nanofluid was measured using capillary viscometers. The mass fractions（w） of copper nanoparticles in the experiment varied between 0.04% and 0.16% with the temperature range of 30-70 ℃. The experimental results show that the temperature and SDBS concentration are the major factors affecting the viscosity of the nano-copper suspensions, while the effect of the mass fraction of Cu on the viscosity is not as obvious as that of the temperature and SDBS dispersant for the mass fraction chosen in the experiment. The apparent viscosity of the copper nano-suspensions decreases with the temperature increase, and increases slightly with the increase of the mass fraction of SDBS dispersant, and almost keeps invariability with increasing the mass fraction of Cu. The influence of SDBS concentration on the viscosity of nano-suspension was relatively large comparing with that of the nanoparticle concentration.

Dependence of viscosity of Cu_9In_4 intermetallics melt on thermal history

The temperature dependence of the dynamic viscosity of Cu9In4 intermetallics melt has been investigated in five kinds of different heating and cooling processes with a torsional oscillation viscometer, It has been found that the viscosity of all Cu9In4 intermetallics decreases with increasing temperature in five kinds of different thermal processes. Thermal history has considerable effect on the viscosity. The viscosity in the cooling process with high superheating is greater than that in the cooling process with low superheating. The viscosity in the heating process is greater than that in the cooling process. No anomalous change in viscosity is measured in three kinds of cooling processes with low superheating. The anomalous change occurs at about 1050℃ in cooling with high superheating and at 800℃ in heating. Furthermore, the structural variation in different thermal processes has also been discussed on the basis of the change in viscosity and DSC analysis.

润滑油低温表观粘度测定及影响因素

在低温下测定润滑油布式粘度的影响因素。分析差异的原因并对实验现象做出了解释。

粘度法测定驱油用聚丙烯酰胺分子量常见问题分析

论述了测量聚丙烯酰胺产品特性粘数及分子量的影响因素。确定了粘度计常数的选取范围,明确稀释溶液浓度的配制要求。分析了不同分子量聚丙烯酰胺在数据处理过程中可能出现的问题。建议取Huggins方程外推截距作为特性粘数值。

Experimental Viscosity Measurements for Copper Oxide Nanoparticle Suspensions

The viscosity of water with copper oxide nanoparticle suspensions was measured using capillary viscometers. The mass fractions of copper oxide nanoparticles in the experiment, w , varied between 0.02 and 0.10, and the temperature range was 30℃ to 80℃. The experimental results show that the temperature was the major factor affecting the viscosity of the nanoparticle suspensions, while the effect of the mass fraction on the viscosity was not so obvious as that of the temperature for the mass fractions chosen in the experiment. The effect of the capillary tube size on the viscosity was also found to be relatively important at higher mass fractions.

Lifetime Evaluation of Medium and Small Size Power Transformers —— Part 2 : Experimental Study

This paper is the experimental verification of the theoretical analysis in Part 1 of a new method to evaluate the lifetime of power transformers. A new experimental method is proposed to detect the degree of polymerization (D P) values during the paper aging process. Experiments show that the aging process of insulating paper is related to the temperature, the oxygen and the water content. If the oxygen and the water content are low, the D P value decreases logarithmically with time. At the same temperature level, D P values are submitted to normal distribution. Applying the presented methodology, expected lifetime of new type of power transformer SBS9 is evaluated.