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You searched for subject:(sound pressure calculation). Showing records 1 – 3 of 3 total matches.

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University of Manchester

1. Li, Qi. Acoustic noise emitted from overhead line conductors.

Degree: PhD, 2013, University of Manchester

The developments of new types of conductors and increase of voltage level have driven the need to carry out research on evaluating overhead line acoustic noise. The surface potential gradient of a conductor is a critical design parameter for planning overhead lines, as it determines the level of corona loss (CL), radio interference (RI), and audible noise (AN). The majority of existing models for surface gradient calculation are based on analytical methods which restrict their application in simulating complex surface geometries. This thesis proposes a novel method which utilizes both analytical and numerical procedures to predict the surface gradient. Stranding shape, proximity of tower, protrusions and bundle arrangements are considered within this model. One of UK National Grid's transmission line configurations has been selected as an example to compare the results for different methods. The different stranding shapes are a key variable in determining dry surface fields. The dynamic behaviour of water droplets subject to AC electric fields is investigated by experiment and finite element modelling. The motion of a water droplet is considered on the surface of a metallic sphere. To understand the consequences of vibration, the FEA model is introduced to study the dynamics of a single droplet in terms of phase shift between vibration and exciting voltage. Moreover, the evolution of electric field within the whole cycle of vibration is investigated. The profile of the electric field and the characteristics of mechanical vibration are evaluated. Surprisingly the phase shift between these characteristics results in the maximum field occurring when the droplet is in a flattened profile rather than when it is ‘pointed’.Research work on audible noise emitted from overhead line conductors is reviewed, and a unique experimental set up employing a semi-anechoic chamber and corona cage is described. Acoustically, this facility isolates undesirable background noise and provides a free-field test space inside the anechoic chamber. Electrically, the corona cage simulates a 3 m section of 400 kV overhead line conductors by achieving the equivalent surface gradient. UV imaging, acoustic measurements and a partial discharge detection system are employed as instrumentation. The acoustic and electrical performance is demonstrated through a series of experiments. Results are discussed, and the mechanisms for acoustic noise are considered. A strategy for evaluating the noise emission level for overhead line conductors is developed. Comments are made on predicting acoustic noise from overhead lines. The technical achievements of this thesis are summarized in three aspects. First of all, an FEA model is developed to calculate the surface electric field for overhead line conductors and this has been demonstrated as an efficient tool for power utilities in computing surface electric field especially for dry condition. The second achievement is the droplet vibration study which describes the droplets' behaviour under rain conditions, such…

Subjects/Keywords: 620.2; audible noise; overhead line conductor; surface potential gradient; electric field calculation; transmission line; conductor bundle; successive image method; charge simulation method; finite element method; high speed camera; droplet vibration; cage experiment; anechoic chamber; hum noise; sound pressure level; free field microphone; partial discharge measurement; UV camera; corona inception; spray system; FFT; A-weighted sound pressure level; overall sound pressure level; hydrophobicity; contact angle

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Li, Q. (2013). Acoustic noise emitted from overhead line conductors. (Doctoral Dissertation). University of Manchester. Retrieved from https://www.research.manchester.ac.uk/portal/en/theses/acoustic-noise-emitted-from-overhead-line-conductors(90a5c23c-a7fc-4230-bbab-16b8737b2af2).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607107

Chicago Manual of Style (16th Edition):

Li, Qi. “Acoustic noise emitted from overhead line conductors.” 2013. Doctoral Dissertation, University of Manchester. Accessed October 14, 2019. https://www.research.manchester.ac.uk/portal/en/theses/acoustic-noise-emitted-from-overhead-line-conductors(90a5c23c-a7fc-4230-bbab-16b8737b2af2).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607107.

MLA Handbook (7th Edition):

Li, Qi. “Acoustic noise emitted from overhead line conductors.” 2013. Web. 14 Oct 2019.

Vancouver:

Li Q. Acoustic noise emitted from overhead line conductors. [Internet] [Doctoral dissertation]. University of Manchester; 2013. [cited 2019 Oct 14]. Available from: https://www.research.manchester.ac.uk/portal/en/theses/acoustic-noise-emitted-from-overhead-line-conductors(90a5c23c-a7fc-4230-bbab-16b8737b2af2).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607107.

Council of Science Editors:

Li Q. Acoustic noise emitted from overhead line conductors. [Doctoral Dissertation]. University of Manchester; 2013. Available from: https://www.research.manchester.ac.uk/portal/en/theses/acoustic-noise-emitted-from-overhead-line-conductors(90a5c23c-a7fc-4230-bbab-16b8737b2af2).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607107

2. Hohenburg, Rainer. Ein Beitrag zur Auslegung von Ultraschallwandlern für Abstandsmessungen.

Degree: 2001, Universität Dortmund

Das Frequenz- und Abstrahlverhalten von Ultraschallwandlern beeinflusst den Einsatz und die Ansteuerung der Systeme für die Abstandsmessung. Verlässliche Aussagen über ihr Verhalten werden durch eine umfassende, realitätsnahe und verifizierte Simulation der Ultraschallwandler ermöglicht. Wesentlicher Bestandteil der Simulation ist die Anwendung der Finite-Elemente-Methode, die durch weitere Berechnungsverfahren unterstützt wird. Die modular aufgebaute Simulationsrech-nung besteht aus den Phasen Spektrogramm-, Verschiebungsprofil- und Schallfeldberechnung. Die Schalldruckverteilung im Fernfeld und deren Druckmaxima in Abhängigkeit von der Frequenz werden mithilfe der Näherungslösung nach dem Huygen-Fresnelschen-Integral berechnet. Die Verifikation der Teilergebnisse wird durch die experimentellen Untersuchungen Schallpegelmessung, Laserinterferometrie und Schallfeldmessung möglich. Die Da-tenbasis wird durch bereits publizierte Kennwerte sowie durch Experimente mit selbst gefertigten Ultraschallwandlern ergänzt. Die ersten Vergleiche der Ergebnisse aus Simulation und Experiment weisen in eine erfolgversprechende Richtung. In der Weiterführung dieser Arbeit wäre eine anwendungsspezifische, kurzfristige und preisgünstige Wandlerherstellung denkbar, bei der Dank zuverlässiger Simula-tionsergebnisse auf umfangreiche experimentelle Untersuchungen verzichtet werden könnte.

The frequency and radiation behaviour of ultrasonic transducers affects the employment and the control of the systems for the distance measurement. Reliable statements about their behaviour are made possible by a comprehensive, close-to-reality and verified simulation of the ultrasonic transducers. A substantial component of the simulation is the application of the finite element method, which is supported by further computation methods. The modularly designed simulation calculation consists of the following phases: spectrogram, displacement field, sound field computation. The sound pressure distribution in the far field and their pressure maxima as a function of the frequency are calculated by means of the approximation solution after the Huygen Fresnel integral. The verification of the partial results is made possible by the experimental investigations of sound level measurement, laser interferometry and sound field measurement. The database is supplemented by characteristic values already published as well as by experiments with self-manufactured ultrasonic transducers. The first comparisons of the results of simulation and experiment are promising. In the continuation of this work a user-specific, short-term and low-priced transducer production might be conceivable even without extensive experimental investigations thanks to reliable simulation results.

Advisors/Committee Members: Schüler, Udo.

Subjects/Keywords: Abstandsmessung; Abstrahlverhalten; distance measurement; dynamic response; far field; Fernfeld; Finite-Elemente-Methode; finite element method; Frequenzverhalten; Laserinterferometrie; laser interferometry; radiation behavior; Schalldruckverteilung; Schallfeldberechnug; Simulation; Simulation; sound pressure calculation; sound pressure distribution; Ultraschallwandler; Ultrasonic transducer; 620

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hohenburg, R. (2001). Ein Beitrag zur Auslegung von Ultraschallwandlern für Abstandsmessungen. (Thesis). Universität Dortmund. Retrieved from http://hdl.handle.net/2003/2813

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hohenburg, Rainer. “Ein Beitrag zur Auslegung von Ultraschallwandlern für Abstandsmessungen.” 2001. Thesis, Universität Dortmund. Accessed October 14, 2019. http://hdl.handle.net/2003/2813.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hohenburg, Rainer. “Ein Beitrag zur Auslegung von Ultraschallwandlern für Abstandsmessungen.” 2001. Web. 14 Oct 2019.

Vancouver:

Hohenburg R. Ein Beitrag zur Auslegung von Ultraschallwandlern für Abstandsmessungen. [Internet] [Thesis]. Universität Dortmund; 2001. [cited 2019 Oct 14]. Available from: http://hdl.handle.net/2003/2813.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hohenburg R. Ein Beitrag zur Auslegung von Ultraschallwandlern für Abstandsmessungen. [Thesis]. Universität Dortmund; 2001. Available from: http://hdl.handle.net/2003/2813

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. Li, Qi. Acoustic Noise Emitted from Overhead Line Conductors.

Degree: 2013, University of Manchester

The developments of new types of conductors and increase of voltage level have driven the need to carry out research on evaluating overhead line acoustic noise.The surface potential gradient of a conductor is a critical design parameter for planning overhead lines, as it determines the level of corona loss (CL), radio interference (RI), and audible noise (AN). The majority of existing models for surface gradient calculation are based on analytical methods which restrict their application in simulating complex surface geometries. This thesis proposes a novel method which utilizes both analytical and numerical procedures to predict the surface gradient. Stranding shape, proximity of tower, protrusions and bundle arrangements are considered within this model. One of UK National Grid's transmission line configurations has been selected as an example to compare the results for different methods. The different stranding shapes are a key variable in determining dry surface fields.The dynamic behaviour of water droplets subject to AC electric fields is investigated by experiment and finite element modelling. The motion of a water droplet is considered on the surface of a metallic sphere. To understand the consequences of vibration, the FEA model is introduced to study the dynamics of a single droplet in terms of phase shift between vibration and exciting voltage. Moreover, the evolution of electric field within the whole cycle of vibration is investigated. The profile of the electric field and the characteristics of mechanical vibration are evaluated. Surprisingly the phase shift between these characteristics results in the maximum field occurring when the droplet is in a flattened profile rather than when it is ‘pointed’.Research work on audible noise emitted from overhead line conductors is reviewed, and a unique experimental set up employing a semi-anechoic chamber and corona cage is described. Acoustically, this facility isolates undesirable background noise and provides a free-field test space inside the anechoic chamber. Electrically, the corona cage simulates a 3 m section of 400 kV overhead line conductors by achieving the equivalent surface gradient. UV imaging, acoustic measurements and a partial discharge detection system are employed as instrumentation. The acoustic and electrical performance is demonstrated through a series of experiments. Results are discussed, and the mechanisms for acoustic noise are considered. A strategy for evaluating the noise emission level for overhead line conductors is developed. Comments are made on predicting acoustic noise from overhead lines.The technical achievements of this thesis are summarized in three aspects. First of all, an FEA model is developed to calculate the surface electric field for overhead line conductors and this has been demonstrated as an efficient tool for power utilities in computing surface electric field especially for dry condition. The second achievement is the droplet vibration study which describes the droplets' behaviour under rain conditions, such as… Advisors/Committee Members: Rowland, Simon, Shuttleworth, Roger.

Subjects/Keywords: audible noise; overhead line conductor; surface potential gradient; electric field calculation; transmission line; conductor bundle; successive image method; charge simulation method; finite element method; high speed camera; droplet vibration; cage experiment; anechoic chamber; hum noise; sound pressure level; free field microphone; partial discharge measurement; UV camera; corona inception; spray system; FFT; A-weighted sound pressure level; overall sound pressure level; hydrophobicity; contact angle

…Figure 6-4 100 Hz Sound Pressure Level at 18 kV/cm Stress for Light Spray Tests ....... 143… …76 Figure 3-41 Sensitivities of Factors for Surface Gradient Calculation… …133 Figure 6-1 FFT Analyzer for Post-processing Sound Signals… …AN). The majority of existing models for surface gradient calculation are based on… …is likely to increase as pressure for compacted tower designs increases. Two new technical… 

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Li, Q. (2013). Acoustic Noise Emitted from Overhead Line Conductors. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:215521

Chicago Manual of Style (16th Edition):

Li, Qi. “Acoustic Noise Emitted from Overhead Line Conductors.” 2013. Doctoral Dissertation, University of Manchester. Accessed October 14, 2019. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:215521.

MLA Handbook (7th Edition):

Li, Qi. “Acoustic Noise Emitted from Overhead Line Conductors.” 2013. Web. 14 Oct 2019.

Vancouver:

Li Q. Acoustic Noise Emitted from Overhead Line Conductors. [Internet] [Doctoral dissertation]. University of Manchester; 2013. [cited 2019 Oct 14]. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:215521.

Council of Science Editors:

Li Q. Acoustic Noise Emitted from Overhead Line Conductors. [Doctoral Dissertation]. University of Manchester; 2013. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:215521

.