Parameter Selection in Cross-Correlation-Based Velocimetry Using Circular Electrostatic Sensors

Cross-correlation methods combined with electrostatic sensing technology offer a promising solution to the online continuous measurement of velocity of particulate solids in pneumatic pipelines. To obtain accurate velocity, the selections of sampling frequency and integral time are critical. The selection of sampling frequency is strongly influenced by the frequency characteristic of the signal. By using finite-element modeling (FEM), the frequency characteristic of the electrostatic sensor was analyzed. To illustrate the particle distribution and the velocity profiles´ influence on the frequency characteristic of the electrostatic signal, an electrostatic velocimetry calibration apparatus was built. Based on the foregoing analysis and taking the measurement error of the transit time and the real application requirement into account, the principles of the selection of sampling frequency and integral time were described.