Anemometer – Combined Calibration of Zero-Flow Timing and Residual Flow-Dependent Positioning Error

Anemometer – Combined Calibration of Zero-Flow Timing and Residual Flow-Dependent Positioning Error

Ultrasonic anemometry and calibration

August 2026

Jacky So

This project investigates calibration methods for an ultrasonic anemometer affected by receiver-positioning error and differences in the dynamic response of flexural ultrasonic transducers (FUTs). Receiver positioning produces both a zero-flow timing offset and a residual flow-dependent error that cannot be removed by zero-flow calibration alone. A combined calibration procedure is developed in which the temperature-dependent FUT response is first characterised, followed by zero-flow calibration and known-flow calibration to determine the remaining positioning response. A mass–spring–damper model is used to relate FUT ring-down behaviour to the steady-state phase during continuous-wave operation. Numerical simulations show that the proposed calibration can recover the flow velocity with very small residual error under the assumed models. The positioning-error calibration is derived from the existing receiver-positioning model, while the proposed FUT phase correction remains to be experimentally validated.

ultrasonic anemometry, ultrasonic sensing, calibration, flexural ultrasonic transducers, FUT, flow measurement, positioning error, zero-flow offset, transit-time difference, temperature compensation, phase response, numerical modelling