Modeling of temperature dependency of structural waves in an ultrasonic flow measurement system

Structural waves transmitted solely through the pipe wall influence the accuracy in a clamp-on ultrasonic flow measurement system because of the superposition with the signals of interest. To improve the measurement against temperature variations, an algorithmic compensation of the structural waves using a temperature model is required. This paper proposes a temperature model for structural waves, using the Matching Pursuit method. In the first section, a sparse signal representation is presented to approximate the structural wave signals. The resulting signal coefficients are used to describe the temperature dependency in a linear model. The method is validated using measurements of structural waves in a circular pipe over a temperature range between 20 degrees C and 80 degrees C. Based on these measurements, the accuracy of the approximated temperature model is evaluated and compared against the baseline signal-stretch method.