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Measurement of properties of flowing yield stress fluids

A yield stress, fluid technology, applied in the field of measuring fluid properties

Active Publication Date: 2020-03-24
HYDRAMOTION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

While traditional methods using captured static samples can be used to make periodic measurements, measurement lags are unavoidable

Method used

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  • Measurement of properties of flowing yield stress fluids
  • Measurement of properties of flowing yield stress fluids
  • Measurement of properties of flowing yield stress fluids

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Experimental program
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Embodiment Construction

[0103] A yield stress fluid effectively behaves like a solid when the shear stress in the fluid is lower than the yield stress. This can happen, for example, when the fluid is at rest or when a large volume of fluid is moving at a uniform velocity. When a flowing material with a yield stress encounters a surface, a velocity gradient is created in a region of the material close to the surface. This gradient results in the development of shear stress within the fluid. Liquified regions will form where these stresses exceed the yield stress of the material. The region of the liquefied layer that results from velocity gradients in the material close to the surface is the boundary layer (BL).

[0104] figure 1 Shows the yield stress fluid in the pipe. There is no flow, so the fluid is at rest. Therefore, there is no velocity gradient in the fluid, so it is unyielded, i.e. solid, at all locations.

[0105] figure 2 Shows a yield stress fluid flowing in a pipe where solid mat...

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Abstract

A model of the viscoplastic boundary layer of a yield stress fluid is described and, based on which, there is provided a method of estimating the yield stress of a flowing yield stress fluid using oneor more vibratory transducers having a vibratory surface in contact with the yield stress fluid, the method comprising: vibrating a vibratory surface of a vibratory transducer to transmit a wave froma vibrating surface into a viscoplastic boundary layer of the flowing yield stress fluid, the wave propagating a distance into the viscoplastic boundary layer; making, using the vibrations of the vibratory transducer, one or more measurements of the degree of damping of vibration; and estimating the yield stress of the flowing yield stress fluid based on the one or more measurements of the degreeof damping of vibration. There are disclosed single-frequency, dual-frequency and triple- frequency modes of operation.

Description

Background technique [0001] The present disclosure relates to techniques and devices for measuring properties of fluids, in particular to determining the yield stress of non-Newtonian fluids. [0002] In a Newtonian fluid, the shear stress is proportional to the shear rate, and the constant of proportionality is the viscosity of the fluid. Thus, viscosity as a single parameter can be used to model or define the relationship between the shear stress and the shear rate of a fluid, and thus the flow behavior of a Newtonian fluid. Water is an example of a Newtonian fluid. [0003] In non-Newtonian fluids, the relationship between shear stress and shear rate is not so simple. The apparent viscosity of a fluid is found to vary with eg shear stress or shear rate. Fluids that exhibit non-Newtonian behavior include ketchup, mayonnaise, and paints. The study of these types of fluid flows is the field of "rheology". [0004] A rheological model has been generated for non-Newtonian f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N11/16G01N11/00
CPCG01N11/162G01N2011/0033G01N2011/0026
Inventor 约汉·加拉格尔
Owner HYDRAMOTION