• Title/Summary/Keyword: Capillary viscometer

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Continuous Viscosity Measurement of Non-Newtonian Fluids over a Range of Shear Rates Using a Mass-Detecting Capillary Viscometer

  • Sehyun Shin;Keum, Do-Young
    • Journal of Mechanical Science and Technology
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    • v.16 no.2
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    • pp.255-261
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    • 2002
  • A newly designed mass-detecting capillary viscometer uses a novel concept to continuously measure non-Newtonian fluids viscosity over a range of shear rates. A single measurement of liquid-mass variation with time replaces the now rate and pressure drop measurements that are usually required by capillary tube viscometers. Using a load cell and a capillary, we measured change in the mass flow rate through a capillary tube with respect to the time, m(t), from which viscosity and shear rate were mathematically calculated. For aqueous polymer solutions, excellent agreement was found between the results from the mass-detecting capillary viscometer and those from a commercially available rotating viscometer. This new method overcomes the drawbacks of conventional capillary viscometers meassuring non-Newtonian fluid viscosity. First, the mass-detecting capillary viscometer can accurately and consistently measure non -Newtonian viscosity over a wide range of shear rate extending as low as 1 s$\^$-1/. Second, this design provides simplicity (i. e., ease of operation, no moving parts), and low cost.

Blood Viscosity Measurements Using a Pressure-Scanning Capillary Viscometer

  • Sehyun Shin;Keum, Do-Young;Ku, Yun-Hee
    • Journal of Mechanical Science and Technology
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    • v.16 no.12
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    • pp.1719-1724
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    • 2002
  • A previously designed capillary viscometer with measuring differential pressure was modified to measure the viscosity of non-Newtonian fluids including unadulterated blood continuously over numerous shear rates in a single measurement. Because of unavoidable experimental noise and a limited number of data, the previous capillary viscometer experienced an inaccuracy and could not directly determine a viscosity without an iterative calculation. However, in the present measurement there are numerous data available near the point of interest so that the numeric value of the derivative, d(In Q)/d(In Q$\sub$w/), is no longer sensitive to the method of differentiation. In addition, relatively low and wide shear rate viscosity measurements were possible because of the present precision pressure-scanning method with respect to time. For aqueous polymer solutions, excellent agreement was found between the results from the pressure-scanning capillary viscometer and those from a commercially available rotating viscometer. In addition, the pressure-scanning capillary viscometer measured the viscosity of unadulterated whole blood without adding any anticoagulants.

Viscosity Measurement in the Capillary Tube Viscometer under Unsteady Flow (비정상유동장에서 모세관점도계의 점도측정)

  • Park, Heung-Jun;Yoo, Sang-Sin;Suh, Sang-Ho
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.825-828
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    • 2000
  • The objective of the present study is to develop a new device that the viscous characteristics of fluids are determined by applying the unsteady flow concept to the traditional capillary tube viscometer. The capillary tube viscometer consists of a small cylindrical reservoir, capillary tube, a load celt system oat measures the mass flow rate, interfacers, and computer. Due to the small size of the reservoir the height of liquid in the reservoir decreases as soon as the liquid in the reservoir drains out through the capillary and the mass flow rate in the capillary decreases as the hydrostatic pressure in the reservoir decreases resulting in a decrease of the shear rate in the capillary tube. The instantaneous shear rate and. driving force in the capillary tube are determined by measuring the mass flow rate through the capillary, and the fluid viscosity is determined from the measured flow rate and the driving force.

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Measurement of the Viscosity of Semi-Soild Foods by Extrusion Capillary Viscometer (Extrusion Capillary Viscometer를 이용한 반고체 식품의 점도 측정 방법)

  • 김길환;이부용;김동만
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.20 no.5
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    • pp.509-512
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    • 1991
  • Rheological property and apparent viscosity(η)of several semi-solid foods were measured with extrusion capillary viscometer. Apparent viscosities of several semi-solid foods ranged from 0.2714 Pa.s to 2.6453 Pa.s Rheological property of spread type semi-solid foods was pseudoplastic (with yield value). Especially, as the moisture content and temperature of Chungkook-jang spread increased, apparent viscosity decreased. On the contrary, as the added soybean oil content of Chungkook-jang spread increased, apparent viscosity also increased.

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Measurements of Blood Viscosity Using a Pressure-Scanning Slit Viscometer

  • Sehyun Shin;Lee, Sung-Woo;Ku, Yun-Hee
    • Journal of Mechanical Science and Technology
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    • v.18 no.6
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    • pp.1036-1041
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    • 2004
  • A newly designed pressure-scanning slit viscometer is developed to combine an optical device without refraction while measuring blood viscosity over a range of shear rates. The capillary tube in a previously designed capillary viscometer was replaced with a transparent slit, which is affordable to mount optical measurement of flowing blood cells. Using a pressure transducer, we measured the change of pressure in a collecting chamber with respect to the time, p(t), from which the viscosity and shear rate were mathematically calculated. For water, standard oil and whole blood, excellent agreement was found between the results from the pressure-scanning slit viscometer and those from a commercially available rotating viscometer. This new viscometer overcomes the drawbacks of the previously designed capillary viscometer in the measuring whole blood viscosity. First, the pressure-scanning slit viscometer can combine an optical instrument such as a microscope. Second, this design is low cost and simple (i.e., ease of operation, no moving parts, and disposable).

Development and Application Capillary Tube Viscometer Transient Flow Concept (과도유동현상을 이용한 모세관점도계 개발 및 적용)

  • Suh, Sang-Ho;Cho, Min-Tae;Kim, Dong-Joo;Roh, Hyung-Woon
    • 유체기계공업학회:학술대회논문집
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    • 2002.12a
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    • pp.489-492
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    • 2002
  • The objective of the present study were to measure the viscosities of non-Newtonian fluids by the transient flow concept in a capillary tube and to apply to hemodynamic studies and pump performance evaluations. The developed capillary tube viscometer could be used to measure the viscosities of the non-Newtonian fluids for a wide range of the shear rate by a run of experiment in a very short time interval. The measured viscosities of water and blood fur different shear rates were good agreement with those of the well established data. The measured viscosities for muddy water varied with the shear rates.

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Viscosity Measurement of Non-Newtonian Fluids Using the Transient Flow Phenomena in the Capillary Tube (모세관내 과도유동현상을 이용한 비뉴턴유체의 점도측정)

  • Cho, Min-Tae;Suh, Sang-Ho;Yoo, Sang-Sin
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.738-741
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    • 2001
  • The purpose of the present study is to measure the viscosity of liquid in the capillary tube viscometer using the unsteady flow concept. The capillary tube viscometer is consisted of a small cylindrical reservoir, capillary tubes, and the mass flow rate measuring system interfaced with computer. Two capillary tubes with 1.152 and 3.002 mm I.D. are used to determine the diameter effects on the viscosity measurements. The instantaneous shear rate and gravitational driving force in the capillary tube are determined by measuring the mass flow rate through the capillary tube instantaneously. The measured viscosities of water and aqueous Separan solution are in good agreement with the reported experimental data.

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Characteristics of Shear-Thinning Fluid Viscosity under Traversal Vibration (진동장에서의 전단박화 유체 점도의 특성 연구)

  • Ku Yun-Hee;Lee Ji-Hyung;Shin Sehyun
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.317-320
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    • 2002
  • The effect of vibration on the viscosity of a shear-thinning fluid was investigated with a newly designed pressure-scanning capillary viscometer. The viscometer was designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time. Low frequency vibration was applied perpendicularly to the direction of the flow. The effect of the transversal vibration was investigated for both Newtonian fluids and non-Newtonian fluids. The experimental results showed that the vibration had no effect on the viscosity of the Newtonian fluids. However, the vibration caused a significant reduction of the shear-thinning fluid viscosity. The viscosity reduction was strongly dependent on both vibration frequency and shear rate. In addition, the viscosity reduction was affected by the amplitude of vibration, and, the bigger amplitude applied, the more viscosity reduction occurred.

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An experimental study on the characteristic times of viscoelastic fluids by falling ball viscometer (낙구식 점도계를 이용한 점탄성 유체의 특성시간에 관한 실험적 연구)

  • 전찬열;유상신
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.241-250
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    • 1990
  • Characteristic relaxation time and characteristic diffusion time of viscoelastic fluids are determined experimentally by measuring the zero-shear-rate viscosity by falling ball viscometer and the infinite-shear-rate viscosity by capillary tube viscometer. Fluids used in experiments are aqueous solutions of polyacrylamide Separan AP-273 and the polymer concentrations range from 300 to 2000 wppm. A newly designed laser beam and timer system is employed to overcome the difficulty in measuring terminal velocities of the low concentration solutions. Ball removal device is prepared to remove the dropped ball from the bottom of cylinder without disturbing the testing fluid. In order to measure the zero-shear-rate viscosity, densities of hollow aluminium balls are adjusted very close to the densities of testing fluids. Characteristic diffusion time, which is ball viscometer. However, terminal velocity of a needle by falling ball viscometer is not affected by the time interval of dropping needles and characteristic diffusion time is not measured with a dropping needle. Powell-Eyring model predicts the highest values of the characteristic relaxation times among models used for heat transfer experimental works for a given polymer solution. As degradation of a polymer solution continues, the zero-shear-rate viscosity decreases more seriously than the infinite-shear-rate viscosity. Characteristic relaxation times of polymer solutions decreases as degradation continues.

Flow Properties of Doenjang (시판된장의 리올로지(Rheology) 특성에 관한 연구)

  • 양신철;김선화
    • Journal of Applied Tourism Food and Beverage Management and Research
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    • v.13 no.1
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    • pp.55-68
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    • 2002
  • Flow properties of doenjang samples at various total solid contents (30, 32, 34, 36, 38, 40%) were evaluated in this study. Flow properties of doenjang samples was determined by using Haake concentric cylinderical viscometer and Instron testing machine with capillary extrusion viscometer, and consistency index(K), and flow behavior index(n) was also determined from power models, and yield stress was derived form Casson models and vanes methods. Doenjang samples showed shear-thinning (pseudoplastic) fluid with small magnitude of flow behavior index(n) (n=0.30-0.55). Casson yield stress was from 2.11 to 64.02(Pa). Vane yield stress was more effective than casson yield stress in property of reactivation. Apparent viscosity was decreased with the increase in temperature and activation energy was in the range of 6.58 to 10.70 kJ/mole. From the capillary extrusion method, K and n was increased with the increase in solid content with good correlation with. The result revealed that capillary extrusion method is useful for measuring the flow properties of doenjang.

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