Measurement of pressure fluctuation characteristics during hydraulic lifting of spherical particles in vertical pipe

In order to reveal the pressure fluctuation induced by particle movement in hydraulic lifting processes, experiments were carried out in a vertical pipe with water as circulating working medium and circular glass beads as particles. The pressure signals at different positions in the experimental section were measured by several pressure transmitters, and the particle motion in the transparent experimental section was observed directly with high speed photographer. The representative pressure signal was determined by analyzing the correlation coefficients of the differential pressure signals and the particle motion images. Using statistical analysis and fast Fourier transform, the average differential pressure pv, average amplitude of differential pressure Av, peak frequency fp, peak frequency amplitude Afp and time-frequency entropy S were extracted. The results show that the characteristics of the particle flow can be detected more accurately and sensitively by the pressure port at 0.5 times of the inner diameter of the pipe. There is no obvious regularity between the characteristic parameters extracted and the pressure fluctuation in the pipe. The experimental correlations based on AvS and Afp/S have the correlation coefficients up to 0.982 and 0.952, and the relative errors between the fitting value and the experimental value are 0.36%-1.68% and 1.05%-5.02%, respectively. © 2019, Central South University Press. All right reserved.