title: Ultrasonic bent waveguides approach for distributed temperature measurement.
abstract: 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.
authors.affiliation: Centre for Non Destructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.
authors.forename: Suresh
authors.initials: S
authors.lastname: Periyannan
authors.affiliation: Centre for Non Destructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.
authors.forename: Prabhu
authors.initials: P
authors.lastname: Rajagopal
authors.affiliation: Centre for Non Destructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India. Electronic address: balas@iitm.ac.in.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Balasubramaniam
keywords: Elevated temperatures at different depths; FEM; Multiple bent waveguide; Sensors; Single bent waveguide; Temperature measurements; Ultrasonic transducers