Ultrasonic flowmeters for liquids and gases are well-established, but the majority use piezoelectric ultrasonic transducers. Whilst very efficient in liquids, piezoelectric transducers tend to be very inefficient in gases and are usually manufactured to be highly resonant to improve transduction efficiency.
Capacitive ultrasonic transducers (CUTs) are highly efficient at generating ultrasound in both liquids and gases, and one of the research areas of the Ultrasonics Research Group in UCC is the application of CUTs to ultrasonic flowmetering in gases. Due to the inherent broadband nature of these transducers, they can operate efficiently over a wide frequency range allowing accurate flowmetering of different gases, and over a range of flow regimes.
The Ultrasonics Research Group has a number of different test facilities with flowmeter test pipes up to 100mm in diameter that allow flow rates of up to 20m/s and the use of different liquids and gases to be studied.
Tomography of pipe flow
Work carried out by the Ultrasonics Research Group has included investigating gas flow in pipes using tomographic imaging. An array of divergent capacitive ultrasonic transducers was constructed for reconstructing images using fan-beam tomography of the lateral flow components in the air flow through a pipe. The image on the left shows simulations of the air flow over a bluff body upstream of the transducer array.
- W. M. D. Wright and S. A. O'Riordan, "Characterization of capacitive ultrasonic transducer gas flow meters", Proc. 26th International Manufacturing Conference (IMC26), Dublin, Ireland, 2nd – 4th September 2009, pp. 207-214 (2009)
- T. M. Dolan and W. M. D. Wright, "Ultrasonic transducers for gas and liquid flow metering", Proc. 24th International Manufacturing Conference (IMC24), Waterford, Ireland, 29th – 31st August 2007, Vol. 1, pp. 301-308 (2007)
- W. M. D. Wright and S. K. Brini, "Capacitive Ultrasonic Transducers for gas flow metering applications", FLOMEKO 2005, Peebles Hotel Hydro, Scotland, 6th - 9th June 2005, paper 1.2 (2005)
- W. M. D. Wright and I. J. O’Sullivan, "Fan-Beam Tomography of Air Flow in Pipes using an Electrostatic Ultrasonic Transducer Array", Proc. 2002 IEEE Ultrasonics Symposium, pp. 696-699 (2003)
- I. J. O’Sullivan and W. M. D. Wright, "Ultrasonic tomographic imaging of air flow in pipes using an electrostatic transducer array", Review of Progress In Quantitative NonDestructive Evaluation, Vol. 22A, Bellingham, Washington 2002, pp. 666-673 (2003)
- I. J. O’Sullivan and W. M. D. Wright, "Ultrasonic measurement of gas flow using electrostatic transducers", Ultrasonics, Vol. 40, No. 1-8, pp. 407-411 (2002)