Abstract: Ultrasonic flowmeters can be achieved dry calibraiton in principle. However, dry calibration technology has not been implemented widespread because of an important factor influencing measurement performance to be further studied. The flow field is disturbed by acoustic transducers in ultrasonic flowmeter. This effect is more sever especially for the medium or small diameter, which perturbation effect on measurement accuracy is more serious. The disturbance mechanism was studied in computational fluid dynamics numerical simulation method which had been verified by experiments. Six acoustic path arrangement types for DN100 flowmeter were compared to research on flow distribution and measurement error caused by different transducer positions, including 1-path, 2-path, 4-path in single and cross measurement planes. It is showed that best measurement performance can be achieved when transducers with cross arrangement are fully inserted into pipe because of throttle effect on flow. Besides, negative measurement error is larger when more acoustic paths are arranged.

Key words: ultrasonic flowmeter;numerical simulation;acoustic transducer;acoustic path arrangement