CFD-DEM Investigation of Lattice-Induced Oscillatory Structures in Horizontal Gas–Solid Two-Phase Flow

Abstract

Low-velocity pneumatic conveying can reduce energy consumption, but particle deposition, pressure fluctuations, and unstable transport remain major challenges in horizontal gas–solid two-phase flow. In this study, a square-section lattice was installed upstream of the particle inlet to generate wake-induced velocity fluctuations and enhance particle suspension. A two-way coupled CFD–DEM method was used to compare the gas–solid flow characteristics of non-lattice and lattice models under an inlet gas velocity of 15 m/s and a solid mass flow rate of 0.24 kg/s. The reliability of the numerical model was first evaluated by comparing the simulated pressure drop per unit length with experimental data, and the maximum relative error was approximately 5.91%. The effects of the lattice on gas-phase velocity distribution, particle trajectories, particle dispersion, collision behavior, pressure loss, and power-consumption-related performance were then investigated. The results show that the lattice generates an asymmetric disturbed wake in the particle acceleration region, redistributes the gas-phase velocity, and enhances transverse velocity fluctuations near the lower part of the pipe. These changes strengthen gas–solid momentum exchange and promote earlier particle suspension. Compared with the non-lattice model, the lattice model reduced the particle dispersion coefficient in the upstream and middle regions by approximately 15.7% on average, indicating a more uniform particle distribution. The total number of particle–particle collisions decreased by approximately 44.3%, whereas particle–wall collisions increased by approximately 27.2% because of the enhanced cross-sectional particle redistribution. In addition, the inlet–outlet pressure drop decreased by approximately 4.8%, and the experimental power-consumption coefficient indicated lower pressure-loss-related power consumption in the low-velocity range. These results demonstrate that, under the investigated operating condition, the square-section lattice can improve particle suspension, weaken dense particle accumulation near the bottom wall, reduce particle–particle collision activity, and provide a mechanically simple passive flow-control method for improving the conveying stability and pressure-loss-related performance of horizontal pneumatic conveying.