Effect of Transducer Shadowing of Ultrasonic Anemometers on Wind Velocity Measurement

An ultrasonic anemometer is a sensor that measures wind velocity based on the principle of time-difference method. However, shadowing effect generated by its transducers is one of the main causes of its measurement error. Therefore, how to obtain the measurement error caused by the shadowing effect has become a problem to be solved. There is a lack of quantitative research on the shadowing effect at different environments. Numerical analysis method for ultrasonic anemometers has been becoming an economical and effective method. To further study the shadowing effect of ultrasonic anemometers, this paper simulates ultrasonic anemometers on the fluid dynamics software FLUENT under the conditions of different wind speeds and directions. Velocity nephograms, vorticity maps and wind speeds along the wind path are obtained and analyzed. Results show that the shadowing at different wind speeds and directions has different effects on the wind measurement accuracy of ultrasonic anemometers. To verify the accuracy of the numerical results, they are compared with those of wind tunnel experiments, which proved that the numerical analysis provides accurate and reliable prediction for the quantitative measurement of wind velocities. Therefore, the numerical method can provide a theoretical basis for reducing the measurement error of ultrasonic anemometers.