Experimental study of installing a dune model in a 90° bend of the horizontal-vertical pneumatic conveying system based on wavelet multi-resolution analysis

In the pneumatic conveying process, the particles move to the bend under the influence of inertia to form a particle rope, which will cause a serious collision between the pipe wall and the particles. In order to reduce energy consumption, three sizes of dune models were designed according to the bend structure and blockage ratio. The system pressure drops, particle flow pattern, particle velocity distribution, and pulsation velocity intensity are studied in this research, and the wavelet multi-resolution analysis is used to perform the particle velocity. The findings indicate that the dune model effectively reduces the ideal conveying gas velocity and pressure drop, and the maximum reduction rate of ideal conveying gas velocity is 10.26%. The dispersion of particles is fully in the vertical pipe in the condition of dune model and the axial velocity is larger than the condition of no model. Moreover, the large-scale low-frequency motion dominates the movement of particles in the pipe, while the appearance of small-scale high-frequency motion breaks the pattern of low-frequency motion.