This paper describes an experimental procedure using ultrasonic waves propagating in a rod to simultaneously measure the viscosity and temperature of melts at high temperatures using a very small amount of sample and without any mechanical rotating equipment. This method has applications in laboratory tests as well as for process monitoring in industries. A refractory material is used as buffer rod in the experiment to transfer the ultrasonic vibrations from a piezoelectric transducer into the melt, which is water cooled to protect the transducer from high temperatures. The sensor is based on the effect of melt viscosity on ultrasonic guided wave reflections from the solid-fluid interface. The difference in the time of flight of the ultrasonic wave in the buffer rod at two different temperatures is used to measure the temperature. The results from the measurement of melt viscosity using the proposed method, on three different glass samples, are in agreement with the values provided by the National Institute of Standards and Technology, USA. This method offers advantages in reduction in the amount of sample, cost, complexity in experiments, experimental time. © 2008 Elsevier B.V. All rights reserved.

Krishnan Balasubramaniam

Department of Mechanical Engineering

Veena Sastha K. Prasad

Elankumaran Kannan

Acoustic waves

Chlorine compounds

Computer networks

Experiments

Guided electromagnetic wave propagation

Hydrodynamics

Offshore oil well production

Piezoelectric transducers

Process engineering

Process monitoring

REFRACTORY MATERIALS

transducers

Ultrasonic waves

Viscosity

Viscosity measurement

BUFFER ROD

Glass

High temperatures

REFLECTION FACTOR

ultrasonic guided wave

Ultrasonics

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Materials Processing Technology

This paper reports on an ultrasonic waveguide sensor for liquid level measurements using three guided wave modes simultaneously. The fundamental wave modes longitudinal L(0,1), torsional T(0,1), and flexural F(1,1) were simultaneously transmitted/received in a thin stainless steel wire-like waveguide using a standard shear wave transducer when oriented at an angle of 45° to the axis of the waveguide. Experiments were conducted in non-viscous fluid (water) and viscous fluid (castor oil). It was observed that the flexural F(1,1) wave mode showed a change in both time of flight (due to the change in velocity and dispersion effects) and amplitude (due to leakage) for different levels (0-9 cm) of immersion of the waveguide in a fluid medium. For the same level of immersion in the fluid, the L(0,1) and the T(0,1) modes show only a relatively smaller change in amplitude and no change in time of flight. The experimental results were validated using finite element model studies. The measured change in time of flight and/or the shift in central frequency of F(1,1) was related to the liquid level measurements. Multiple trials show repeatability with a maximum error of 2.5% in level measurement. Also, by monitoring all three wave modes simultaneously, a more versatile and redundancy in measurements of the fluid level inside critical enclosures of processing industries can be achieved by compensating for changes in the fluid temperature using one mode, while the level is measured using another. This ultrasonic waveguide technique will be helpful for remote measurements in physically inaccessible areas in hostile environments. © 2019 Author(s).

Fulltext

Review of Scientific Instruments

Ultrasonic waveguide based level measurement using flexural mode F(1,1) in addition to the fundamental modes

This paper reports the feasibility of using an ultrasonic waveguide sensor for distributed temperature measurement in two different case studies, that is: 1) skin temperature of a solid structure (pipe) and 2) fluid (water). This technique improves upon the conventional multiple thermocouples approach for multi-level temperature measurements. The range of temperatures is from room temperature to maximum utility temperature for the two case studies (85 °C for water and 200 °C for pipe). Using the interaction of the propagating ultrasonic waves in a thin rodlike waveguide with intentionally designed geometric discontinuities (bends, axisymmetric, non-axisymmetric notches, and so on), the localized information on the temperature is extracted. An ultrasonic technique for accurate temperature measurement by tracking the time-of-flight of reflected guided wave modes from appropriately spaced notch reflectors is therefore proposed here, while using the reflection from a bend is used as a reference. Using a finite element model approach, the notch size and/or the bend radius were selected in order to reduce mode conversion effects as well as to obtain uniform amplitudes of the reflected signals from these designed discontinuities. The numerical results were experimentally validated for the L(0,1) wave mode using a stainless steel waveguide sensor. This paper is of interest to industrial applications including mould cooling jacket temperature monitoring during the steel manufacturing process as well as for furnace wall temperature measurements in petrochemical industries. © 2001-2012 IEEE.

IEEE Sensors Journal

Ultrasonic waveguide-based multi-level temperature sensor for confined space measurements

Ultrasonic waveguide-based sensing, that permit robust measurements and sensing, is discussed in this paper. The use of ultrasonic guided waves has several advantages including remote measurements, multi-modal nature allowing for measurement of different parameters, small footprint, low cost, multi-point measurements on the same waveguide and most importantly robustness. These inherent qualities of ultrasonic waveguide-based sensing are particularly useful in industrial applications. One of the key applications that will be described will be the measurement of E and G moduli of materials as a function of temperature over a wide range of materials will be demonstrated. Knowing the moduli as a function of temperature, the measurement of physical properties such as temperature, rheology, fluid level, etc. of the surrounding fluid material can be accomplished using several embodiments of the waveguides using the fundamental wave modes such as L(0,1), T(0,1) and F(1.1). In addition, it will be shown that under sodium imaging in large plant conditions can be performed using ultrasonic waveguides using the A0 modes. © 2018 IEEE.

Proceedings of IEEE Sensors

Ultrasonic Waveguide Sensors for Measurements in Process Industries

This paper studies the propagation of ultrasound in spiral waveguides, towards distributed temperature measurements on a plane. Finite Element (FE) approach was used for understanding the velocity behaviour and consequently designing the spiral waveguide. Temperature measurements were experimentally carried out on planar surface inside a hot chamber. Transduction was performed using a piezo-electric crystal that is attached to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes L(0,1) and T(0,1) were employed. Notches were introduced along the waveguide to obtain ultrasonic wave reflections. Time of fight (TOF) differences between the pre-defined reflectors (notches) located on the waveguides were used to infer local temperatures. The ultrasonic temperature measurements were compared with commercially available thermocouples. © 2017 Author(s).

AIP Advances

Multiple temperature sensors embedded in an ultrasonic “spiral-like” waveguide

This paper describes novel techniques for simultaneous measurement of temperatures at multiple locations using two configurations (a) a single transducer attached to multiple waveguides of different lengths (each with a single bend) and (b) single waveguide with multiple bends connected to single transducer. These techniques improve upon the earlier reported studies using straight waveguides, where the non-consideration of the effect of temperature gradients was found to be a major limitation. The range of temperature measurement is from room temperature to maximum utility temperature of the waveguide material. The time of flight difference of reflected ultrasonic longitudinal guided wave modes (L(0, 1)) from the bend, which is the reference signal, and another signal from the end of the waveguide, is utilized to measure the local temperature of the surrounding media. Finite element simulations were employed to obtain the appropriate dimensions and other design features of the multiple bent waveguide. This work is of interest to several industrial applications involving melters and furnaces. © 2016

Ultrasonic bent waveguides approach for distributed temperature measurement

Viscosity measurements of melts at high temperatures using ultrasonic guided waves

Journal	Journal of Materials Processing Technology
ISSN	09240136
Open Access	No