METHODS FOR IMPROVING THE ACCURACY OF ULTRASONIC GAS FLOWMETERS BASED ON CLAMP-ON SENSORS SHEAR AND LAMB WAVES

The use of clamp-on ultrasonic gas flow meters offers reduced maintenance costs, increased safety and applicability to high pressure or corrosive gas systems. Clamp-on ultrasonic gas flow meters, although offering significant advantages such as non-invasiveness, ease of installation and operational flexibility, often face difficulties in achieving the same accuracy as in-line flow meters. This is especially true for gas applications due to the high acoustic impedance mismatch between the transducer, pipe wall and gas. However, advances in ultrasonic wave propagation techniques, especially with respect to shear waves and Lamb waves, along with improved signal processing and installation techniques, offer real promise for improving their measurement accuracy. The objective of this study is to select and analyze methods to overcome these limitations, with a special emphasis on the different roles of shear wave and Lamb wave technologies. This paper discusses key strategies for improving the accuracy of clamp-on ultrasonic flowmeters, including optimized transducer designs; advanced digital signal processing algorithms such as cross-correlation and variational mode decomposition; the use of computational fluid dynamics for real-time flow profile correction; and complex real-time compensation for dynamic changes in temperature, pressure, and gas composition. Lamb wave-specific accuracy improvement techniques such as dispersion compensation and temperature sensitivity mitigation are also discussed. The integration of advanced diagnostics and the exploration of new technologies such as machine learning and new piezoelectric materials represent a cutting-edge path to achieving highly accurate, reliable clamp-on gas flow measurement.