Title :
3J-3 Reciprocal Operation of Ultrasonic Transducers: Experimental Results
Author :
Borg, Johan ; Johansson, Jonny ; Van Deventer, Jan ; Delsing, Jerker
Author_Institution :
EISLAB, Lulea Univ. of Technol.
Abstract :
Ultrasonic transit-time flow-meters estimate fluid or gas flows from the difference in times of flight of upstream and downstream acoustic pulses. However, any delay differences arising from sources other than the flow to be measured will cause a troublesome "zero flow" offset error. In theory, the transducers used in the measurement system should not influence the zero flow error, as electroacoustic systems based on piezoelectric transducers have been shown to be reciprocal (when the media is stationary). However, care is required when designing the electrical interfaces for the piezoelectric transducers, if reciprocity in the system is to be utilized. This work presents technique and measurements that apply reciprocity to an ultrasonic transit-time flow-meter. Specialized electrical transducer interfaces with options to drive the transducers from either low or high impedance sources were used. Combined with a high-impedance receive mode these options made it possible to change the conditions for reciprocity in the system. We show reduced delay difference in 9 cases out of 10 when trying to utilize the reciprocal property compared to when we disregard it in favor for larger excitation energy. The delay improvements were accompanied by reduced differences between the center frequencies of the signals from the two paths
Keywords :
flowmeters; piezoelectric transducers; ultrasonic transducers; electrical transducer interfaces; electroacoustic systems; fluid flow; gas flow; impedance sources; piezoelectric transducers; ultrasonic transducers; ultrasonic transit-time flow-meters; Acoustic measurements; Acoustic pulses; Acoustic transducers; Delay; Fluid flow; Fluid flow measurement; Impedance; Piezoelectric transducers; Ultrasonic transducers; Ultrasonic variables measurement;
Conference_Titel :
Ultrasonics Symposium, 2006. IEEE
Conference_Location :
Vancouver, BC
Print_ISBN :
1-4244-0201-8
Electronic_ISBN :
1051-0117
DOI :
10.1109/ULTSYM.2006.263