Directional Properties of Ultrasonic Antenna Array
Proper using of long-range ultrasonic (LRUT) technique for different test pipe configuration, and test conditions according to the technical task requires comprehensive knowledge of ultrasonic field generated by ultrasonic phased antenna array. This chapter shows results calculated for ultrasonic beam spreading by antenna array in pipe and receiving its reflection from the pipe wall edge. The results show influence of antenna array with different characteristics to directional properties of ultrasonic field. The calculations of the ultrasonic fields are carried out using numerical method based on principles of Huygens and Fermat. In any point of interest in researched area, it is calculated interference of waves emitted from all elements of the phased antenna array. The results are present in type of distance and circumference amplitude curves for point source located at the center of the active group replacing the antenna array. Any point of interest on pipe wall edge is also present as secondary source of spherical waves by point spread function. Directional properties of active focused and unfocused ultrasonic antenna array are studied for torsional mode T(0, 1) emitted in pipe. Possibilities to use the antenna array focusing technology in pipeline testing by LRUT technique are discussed.
KeywordsLong-range ultrasonic technique (LRUT) Torsional mode Active and synthetic focusing techniques Dynamic distance focusing (DDF) Phased antenna array Focal law Distance and circumferential amplitude curves Full width at half maximum (FWHM)
- 1.G. Kino, Acoustic Waves: Devices, Imaging and Analogue Signal Processing (Prentice-Hall, New Jersey, 1987)Google Scholar
- 2.J. Davies, Inspection of Pipes Using Low Frequency Focused Guided Waves, Ph.D. thesis. Imperial College, University of London (2008)Google Scholar
- 4.I. Ermolov, A. Vopilkin, V. Badalyan, Calculations in Ultrasonic Testing (Echo+, Moscow, 2000). (In Russian)Google Scholar
- 5.J. Davies, F. Simonetti, M. Lowe, P. Cawley, Review of synthetically focused guided wave imaging techniques with application to defect sizing, in Review of Progress in Quantitative NDE, vol. 25, ed. by D.O. Thompson, D.E. Chimenti (American Institute of Physics, Melville, New York, 2006), p. 142Google Scholar