Ultrasonic probes and echo time algorithms in ultrasonic gas flow measurement systems: Progress and perspectives.

This article provides a comprehensive review of ultrasonic gas flowmeters, focusing on their measurement principles, key components, and recent technological advancements aimed at improving accuracy and stability. It emphasizes the widely used transit-time method for flow measurement, discusses the development and modeling of piezoelectric ultrasonic transducers—including innovations in materials and array structures—and details hardware circuit designs incorporating high-precision time-to-digital converters (TDCs). The review also covers advanced echo signal processing techniques, such as envelope fitting, cross-correlation, and Kalman filtering, which enhance signal detection and measurement reliability. Future research directions highlighted include improving transducer performance under extreme conditions, optimizing excitation circuits with integrated and adaptive designs, and integrating artificial intelligence and big data for enhanced data analysis and fault diagnosis in complex gas flow scenarios.