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Method for measuring fluid shear stress in capillary and device

A technology of fluid shearing and measurement methods, which is applied in the direction of direct current flow characteristics measurement, etc., can solve problems such as capillary effects that cannot be completely eliminated, achieve the effects of eliminating pressure correction links, simplifying rheological test operations, and improving test accuracy

Inactive Publication Date: 2012-01-18
HUNAN UNIV OF TECH +1
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Problems solved by technology

More importantly, the two processing methods can only reduce the error of the measurement results, and cannot completely eliminate the influence of the pressure drop in the capillary inlet area and the outlet area on the measurement of the shear stress of the fluid in the tube.

Method used

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  • Method for measuring fluid shear stress in capillary and device
  • Method for measuring fluid shear stress in capillary and device
  • Method for measuring fluid shear stress in capillary and device

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Embodiment Construction

[0014] The flow field of the sample fluid near the capillary is as follows: figure 1 shown. The sample is squeezed out of the capillary in the large-diameter barrel 13, and there is an obvious streamline convergence behavior near the capillary inlet, so that the sample can only develop into a stable streamline-parallel laminar flow after flowing into the capillary for a certain distance; the capillary Near the outlet, because of the sudden disappearance of the pipe wall constraints, the sample streamline changes accordingly. Therefore, the flow of the sample in the capillary can be divided into three zones: the inlet zone 6 , the laminar flow zone 7 , and the outlet zone 8 .

[0015] The existing capillary rheometer measures the pressure of the sample by installing the pressure sensor 1 at the position A above the capillary inlet zone 6, so as to estimate the shear stress in the capillary tube, which will inevitably introduce the pressure drop from the inlet zone 6 and the ou...

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Abstract

The invention discloses a method for measuring the fluid shear stress in a capillary and an implementing device thereof, and belongs to the field of material testing. The method comprises the following steps of: slicing a capillary die into at least three sections, i.e. an inlet section, a middle section and an outlet section, along the axial direction according to differences of test sample fluid in the capillary in the flow condition; and only measuring the stress of a test sample at the position of the middle section so as to calculate the shear stress of the test sample in the capillary. The measuring device for implementing the method comprises a charging barrel, a plunger rod, the capillary die and a force measuring element. The force measuring element is arranged in the middle section of the die and can be used for measuring an acting force between the middle section and the outlet section. In the testing process, the test sample in the charging barrel outflows through the capillary under the squeezing action of the plunger rod. The change of a force value measured in the middle section of the die corresponds to the shear force applied to the capillary wall of the middle section of the die. Due to the adoption of the method and the implementing device thereof, the influence of a pressure drop of an inlet region and an outlet region in a capillary rheometer on the measurement of the fluid shear stress in the capillary is completely eliminated, and the testing accuracy of the capillary rheometer is promoted.

Description

technical field [0001] The invention relates to the field of material testing, in particular to a capillary rheological property testing system. Background technique [0002] The rheometer is a key instrument for measuring the viscoelasticity index of materials, analyzing the microstructure and macroscopic processing properties of materials, and is a common tool for studying material formula and processing parameters. Rheometers mainly include capillary rheometers, rotational rheometers, and torque rheometers. Among them, capillary rheometers are widely used because of their wide measurement range and similar material flow to typical processing and molding processes. [0003] In a capillary rheometer, the shear stress of the sample fluid in the capillary is one of the core physical quantities for solving the shear viscosity of the sample. The existing capillary rheometer measures the fluid pressure at the capillary inlet through a pressure sensor installed above the capilla...

Claims

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Application Information

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IPC IPC(8): G01N11/04
Inventor 黄宇刚刘跃军李祥刚赵素华
Owner HUNAN UNIV OF TECH
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