Distributed temperature sensors development using an stepped-helical ultrasonic waveguide
20 Apr 2018-Vol. 1949, Iss: 1, pp 090010
TL;DR: In this article, a multi-location measurement wave-guide, with a measurement capability of 18 locations in a single wire, has been fabricated using a stepped-helical spring configuration.
Abstract: This paper presents the design and development of the distributed ultrasonic waveguide temperature sensors using some stepped-helical structures. Distributed sensing has several applications in various industries (oil, glass, steel) for measurement of physical parameters such as level, temperature, viscosity, etc. This waveguide incorporates a special notch or bend for obtaining ultrasonic wave reflections from the desired locations (Gage-lengths) where local measurements are desired. In this paper, a multi-location measurement wave-guide, with a measurement capability of 18 locations in a single wire, has been fabricated. The distribution of these sensors is both in the axial as well as radial directions using a stepped-helical spring configuration. Also, different high temperature materials have been chosen for the wave-guide. Both lower order axi-symmetric guided ultrasonic modes (L(0,1) and T(0,1)) were employed. These wave modes were generated/received (pulse-echo approach) using conventional longitu...
TL;DR: In this article , an ultrasonic waveguide technique using U-shaped configurations to measure the fluid level was reported. But the level measurement experiments were performed based on the drop in amplitude and change in time of flight of the received sensor signals.
Abstract: This paper reports an ultrasonic waveguide technique using U-shaped configurations to measure the fluid level. The longitudinal L(0,1) wave mode was propagated in the waveguide using through-transmission (TT) and pulse-echo (PE) techniques simultaneously using a single shear transducer. Initially, we used the Finite Element Method (FEM) to study the waveguide's wave propagation behavior while immersed in various fluids. Develop the level sensor using the waveguide’s first and second pass signals, corresponding to TT and PE. We have performed the level measurement experiments based on the drop in amplitude and change in time of flight of the received sensor signals. Studied the sensor’s sensitivity using TT1, PE1, TT2, and PE2 signals (1 and 2 represent first and second pass signals, respectively) with different fluid levels (petrol, water, castor oil, and glycerin). A comparison study was performed between straight waveguides using PE and U-shaped waveguides using TT techniques to find the limitations of waveguide sensors. During level-sensing experiments, the average error for U-shaped and straight waveguides was identified as 3.5% and 5.6%, respectively. We studied signal attenuation from straight and U-shaped waveguide sensors based on the sensor surface and dead-end region. In the designed U-shape waveguide, only the wave leakage effect was considered, avoiding the dead-end reflection during the immersion of the sensor in liquid and allowing for more fluid depth measurements. In addition, the U-shaped waveguide was further used for fluid-level sensing using three wave modes [L(0,1), T(0,1), and F(1,1)] simultaneously. This sensor can monitor fluid levels in hostile environments and inaccessible regions of power plants, oil, and petrochemical industries.
01 Jan 1997
TL;DR: In this article, a general-purpose program that can create dispersion curves for a very wide range of systems and then effectively communicate the information contained within those curves is presented, using the global matrix method to handle multi-layered Cartesian and cylindrical systems.
Abstract: The application of guided waves in NDT can be hampered by the lack of readily available dispersion curves for complex structures. To overcome this hindrance, we have developed a general purpose program that can create dispersion curves for a very wide range of systems and then effectively communicate the information contained within those curves. The program uses the global matrix method to handle multi-layered Cartesian and cylindrical systems. The solution routines cover both leaky and non-leaky cases and remain robust for systems which are known to be difficult, such as large frequency-thicknesses and thin layers embedded in much thicker layers. Elastic and visco-elastic isotropic materials are fully supported; anisotropic materials are also covered, but are currently limited to the elastic, non-leaky, Cartesian case.
19 Jul 2013
TL;DR: This chapter discusses applications of Interface Measurement, Proximity Sensing, and Gaging Applications, and Theory and Measurement Techniques, as well as special Topics, including Elastic Moduli Applications.
Abstract: Introduction. Scope of Applications. Theory and Measurement Techniques. Flow Applications. Temperature Applications. Density Applications. Interface Measurement, Proximity Sensing, and Gaging Applications. Elastic Moduli Applications. Other Parameters--Special Topics. Historical Notes and Anecdotes. References. Index.
TL;DR: In this paper, a non-orthogonal curvilinear coordinate system that is translationally invariant along the helix centerline is proposed, so that a Fourier transform is explicitly performed and the problem is reduced to two dimensions.
Abstract: The goal of this paper is to theoretically investigate the propagation of elastic waves in helical waveguides. In the context of non-destructive evaluation for structural health monitoring, this study is motivated by the need for inspecting helical structures such as cables or springs. A numerical method is chosen based on a semi-analytical finite element technique. The proposed method relies on a non-orthogonal curvilinear coordinate system that is translationally invariant along the helix centreline, so that a Fourier transform is explicitly performed and the problem is reduced to two dimensions. Some useful expressions are also derived for the averaged energy and flux in order to directly compute the energy velocity. The convergence and accuracy of the proposed method are then assessed by comparing finite element results with reference solutions. A dispersion analysis inside a 7.5° helical wire, typically encountered in civil engineering cables, is realised including attenuation due to material damping. Some dispersion curves are finally presented for a wide range of lay angles and for several centreline radii. Significant differences with the infinite cylinder are observed.
TL;DR: In this paper, the authors proposed a helical coordinate system that preserves translational invariance along the helix centerline to explicitly perform a spatial Fourier transform and showed that for the analysis of multi-wire helical strands a twisting system is translationally invariant.
Abstract: Elastic guided waves have some potential for non-destructive inspection of civil engineering multi-wire steel cables. However, wave propagation inside such structures is not yet fully understood. This paper investigates multi-wire helical waveguides with special attention to the common seven-wire strand configuration (one straight core surrounded by one layer of six helical wires). A helical coordinate system is first proposed. Though non-orthogonal, this system preserves translational invariance along the helix centreline to explicitly perform a spatial Fourier transform. Then, it is shown that for the analysis of multi-wire helical strands a twisting system—which is a special case of helical systems—is translationally invariant. A semi-analytical finite element method is developed reducing the problem on the cross-section only. A straightforward computation of energy velocity is proposed. Dispersion curves for a single straight wire and a helical wire are first computed to verify the adequacy of the twisting system. Finally the seven-wire strand is analysed using simplified contact conditions. Theoretical dispersion curves are compared to low-frequency magnetostrictive measurements. Good agreement is found for the first compressional-like mode and its associated veering central frequency (‘notch frequency’).
TL;DR: In this article, an ultrasonic sensor that simultaneously measures temperature and viscosity of molten materials at very high temperature is described, based on ultrasonic shear reflectance at the solid-melt interface.
Abstract: An ultrasonic sensor that simultaneously measures temperature and viscosity of molten materials at very high temperature is described. This sensor has applications as a process monitor in melters. The sensor is based on ultrasonic shear reflectance at the solid–melt interface. A delay line probe is constructed using refractory materials. A change in the time of flight within the delay line is used to measure the temperature. The results obtained from this sensor on various calibration glass samples demonstrate a measurement range of 100–20 000 P for the viscosity and 25–1500 °C for the temperature.