Abstract:The effects of nonlinear ultrasonic propagation on high-speed ultrasonic gas flow measurement are analyzed based on the sound line equation derived from Snell's geometric acoustic law. A mathematical model for the ultrasonic propagation path in ultrasonic flowmeter pipe is built, and the relationship between x and r is calculated by MATLAB programming and ode45 simulating. The ultrasonic propagation path at the flow rate of 3∼30m/s is simulated in the assumed boundary conditions of the pipeline, transducer installation and fluid state. It shows that the nonlinear propagation characteristics cause the large deviations of the position of received ultrasonic waves in conditions of different flow rates, which strongly affects the stability and accuracy of flow measurement. The simulated offset data of the receiving position are useful for the high-speed gas ultrasonic flowmeter installation and dry calibration on clamp-on ultrasonic flowmeters.