Abstract: Flow velocity measurement, as an important part of flood warning, is significant, but the accuracy of conventional instrument is poor, therefore, a polarity correlation algorithm is present for flow velocity measurement. This paper summarizes the basic principle of correlation method in the flow velocity measurement, and then advances an improved algorithm of polarity correlation method. Then the algorithm analysis and circuit implementation are carried out. The simulation experiments based on the Monte Carlo method show that the polarity correlation algorithm can replace common correlation algorithms on peak point determination. It has good anti-interference function due to the particularity of the algorithm. The comparison of experimental measurement speed with the speed setting by the Monte Carlo method shows that if the two sampling sensor spacing meet certain conditions, the measurement speed and its fitted curve could have a better Goodness of Fit, and the measurement speed can accurately response the speed set by the Monte Carlo method. Which can validate the feasibility of the algorithm and have an accurate measurement on flow velocity.

Key words: flow velocity measurement, polarity correlation algorithm, peak point, correlation function