Stepping-Motor-Driven Constant-Shear-Rate Rotating Viscometer

We present a novel, non-contact, and non-optical approach to actuation and sensing. In the developed method, both functions are based only on the alternating magnetic field and take place simultaneously. The article demonstrates the technique in one of its potential applications, i.e. rheometry. The developed device uses two orthogonal pairs of inductor coils to generate a rotating magnetic field. The field actuates a rotor with an embedded NdFeB ring magnet. The angular displacement is simultaneously monitored with an angular AMR sensor, placed underneath the rotor. The device is used to study aqueous solutions at different concentrations of glycerol (10-95%). The accuracy of the angular sensing is verified using machine vision and pattern recognition, which is a technique widely used in the existing viscometers. A new approach to viscosity probing and phase slipping detection is introduced. So far, in non-contact rotational viscometers the dynamic viscosity was related to a critical frequency, determined by altering the frequency of the rotating magnetic field. However, we propose to alter the magnitude of the field, by changing the current in the inductor coils. The frequency is kept constant and the viscosity is proportional to the amplitude of current, for which the phase slipping occurs. The applied rate of rotation can be optimized for a particular measurement scenario. The results suggest a great potential of the technique in a variety of scenarios. Simultaneous magnetic actuation and sensing enables application in a broad frequency band, from dc to tens of kilohertz. Moreover, the design of a measurement device is simplified, so that its cost can be significantly lower than that of a conventional system. Furthermore, presented method is non-contact, does not require a clear optical path, and could be less susceptible to the environmental conditions (e.g. poor illumination, or full immersion in the studied solution).

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“…to enable high shear rate viscometry [13]. The existing devices employ dc, ac, and stepper motors for the actuation purpose [14].…”

Section: Rheometrymentioning

confidence: 99%

Simultaneous magnetic actuation and observation with ferromagnetic sensors

Czajkowski

Kinnunen

Haapanen

et al. 2015

Meas. Sci. Technol.

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“…The method of measuring magnetoresistance would also bring frictional resistance to the inner cylinder, resulting in low accuracy of the system. De Lucena and Kaiser 11 designed a stepping-motor-driven rotating viscometer and studied the effect of the step size of the stepping motor on the measurement data. But at the same time they ignored the influence of friction resistance of the inner cylinder.…”

Section: Introductionmentioning

confidence: 99%

Designing of a double-cylinder viscometer for high-pressure liquids

Liu

et al. 2020

Measurement and Control

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In this work, a double-cylinder viscometer is designed to measure dynamic viscosity over a pressure range from atmospheric pressure up to 150 MPa and a temperature range of 278.15–333.15 K. A high-pressure closed cavity is designed innovatively and the magnetic coupling is adopted to transfer the torque to reduce the friction; the inner cylinder with ruby bearing is designed to reduce the friction torque, thus the accuracy of the viscosity measurement is improved. The experiment of measuring the standard viscosity liquid (N10 and N35) under normal pressure and measuring the viscosity of methylbenzene under the pressure of 0.1–150 MPa were carried out, and considering all the experimental data, the uncertainty of the viscosity measurements is approximately ±3%.

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