Time domain numerical modelling of guided wave excitation in fluid-filled pipes

© 2022 The Author. Published by Elsevier B.V. This is an open access article under the CC BY licence. https://creativecommons.org/licenses/by/4.0/Acoustic waves have been widely used to inspect pipeline defects, including leakage, blockage and corrosion etc. The time-domain excitation of guided waves in the fluid/solid coupled pipeline system has rarely been studied theoretically. This requires the incorporation of a source term in the coupled system. This article introduces a finite element based numerical model to study the excitation of guided waves in the coupled system with a sound source either in the fluid or on the pipe wall. A compatible pair of time-domain Perfectly Matched Layers (PMLs) have been proposed to absorb pipe end reflections in the elastic wall and in the fluid respectively. These fluid/solid PML numerical formulations are coupled and the implementation of the coupling is introduced. The numerical model is validated against an enlarged model without PML, and excellent agreement has been achieved. The numerical model shows that the dominant excited wave mode is a fluid type wave mode when the sound source is a fluid source or a radial elastic line source. However, the dominant excited wave mode is a structure type wave mode when the sound source is an axial elastic line source.Peer reviewe

A hybrid finite element approach to modeling sound radiation from circular and rectangular ducts

This is the post-print version of the Article - Copyright @ 2012 Acoustical Society of AmericaA numerical model based on a hybrid finite element method is developed that seeks to join sound pressure fields in interior and exterior regions. The hybrid method is applied to the analysis of sound radiation from open pipes, or ducts, and uses mode matching to couple a finite element discretization of the region surrounding the open end of the duct to wave based modal expansions for adjoining interior and exterior regions. The hybrid method facilitates the analysis of ducts of arbitrary but uniform cross section as well the study of conical flanges and here a modal expansion based on spherical harmonics is applied. Predictions are benchmarked against analytic solutions for the limiting cases of flanged and unflanged circular ducts and excellent agreement between the two methods is observed. Predictions are also presented for flanged and unflanged rectangular ducts, and because the hybrid method retains the sparse banded and symmetric matrices of the traditional finite element method, it is shown that predictions can be obtained within an acceptable time frame even for a three dimensional problem.This study is supported by the U.K. Engineering and Physical Sciences Research Council (EPSRC)

ANALYSIS OF LEAKAGE FLOW AND DYNAMIC CHARACTERISTICS IN FLOATING RING SEALS FOR HIGH PRESSURE TURBOPUMP

ABSTRAC

On the scattering of elastic waves from a non-axisymmetric defect in a coated pipe

Viscoelastic coatings are often used to protect pipelines in the oil and gas industry. However, over time defects and areas of corrosion often form in these pipelines and so it is desirable to monitor the structural integrity of these coated pipes using techniques similar to those used on uncoated pipelines. A common approach is to use ultrasonic guided waves that work on the pulse-echo principle; however, the energy in the guided waves can be heavily attenuated by the coating and so significantly reduce the effective range of these techniques. Accordingly, it is desirable to develop a better understanding of how these waves propagate in coated pipes with a view to optimising test methodologies, and so this article uses a hybrid SAFE-finite element approach to model scattering from non-axisymmetric defects in coated pipes. Predictions are generated in the time and frequency domain and it is shown that the longitudinal family of modes is likely to have a longer range in coated pipes when compared to torsional modes. Moreover, it is observed that the energy velocity of modes in a coated pipe is very similar to the group velocity of equivalent modes in uncoated pipes. It is also observed that the coating does not induce any additional mode conversion over and above that seen for an uncoated pipe when an incident wave is scattered by a defect. Accordingly, it is shown that when studying coated pipes one need account only for the attenuation imparted by the coating so that one may normally neglect the effect of coating on modal dispersion and scattering

Development and research trends of a polypropylene material in electrical engineering: A bibliometric mapping analysis and systematical review

In order to explore the development and research trends of polypropylene (PP) in electrical engineering, the research literature is quantitatively analyzed using a bibliometric method with the VOSviewer and CiteSpace software. First, the research literature about PP material in electrical engineering applications is collected, from 1990 to 2022. Then, by analyzing the keyword co-occurrence, keyword co-occurrence timezone, author cooperation network, and national cooperation network, the research hotspots of the PP field and its time evolutionary path and development direction are introduced. It is found that the nano-modification, mechanical, and electrical properties are the most popular research hotspots in this field. Most research studies were completed by few specific researchers. A stable cooperative group has not been formed in this field yet, indicating the necessity of further integration. Most articles about PP were published in dielectric and material journals. It is suggested that more open access journals are required to popularize the existing research results among the public and to promote the development of PP. Although the most published country is China, the United States publishes the most cited papers on average

Upconversion NIR-II fluorophores for mitochondria-targeted cancer imaging and photothermal therapy

Acknowledgements: The work was supported by the National Key R&D Program of China (2020YFA0908800), NSFC (81773674, 81573383), Shenzhen Science and Technology Research Grant (JCYJ20190808152019182), Hubei Province Scientific and Technical Innovation Key Project, National Natural Science Foundation of Hubei Province (2017CFA024, 2017CFB711), the Applied Basic Research Program of Wuhan Municipal Bureau of Science and Technology (2019020701011429), Tibet Autonomous Region Science and Technology Plan Project Key Project (XZ201901-GB-11), the Local Development Funds of Science and Technology Department of Tibet (XZ202001YD0028C), Project First-Class Disciplines Development Supported by Chengdu University of Traditional Chinese Medicine (CZYJC1903), Health Commission of Hubei Province Scientific Research Project (WJ2019M177, WJ2019M178), the China Scholarship Council, and the Fundamental Research Funds for the Central Universities.Peer reviewedPublisher PD