This study investigates the motion and fragmentation of non-spherical particles in pipeline pneumatic conveying, using gangue particles as the research object. The effects of airflow velocity and particle shape on the picking characteristics, as well as the influence of elbow angle, airflow velocity, particle size, and air pressure on particle crushing, were analyzed through a combination of Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) coupled simulations and experiments. Orthogonal experiments were conducted to determine the optimal combination of parameters for minimizing particle breakage rates and pipeline pressure drops. The results show that the airflow velocity significantly affects the pick-up rate of particles, while particle shape also plays a key role, with higher sphericity resulting in lower pick-up rates. Among the factors influencing particle breakage, airflow velocity has the most pronounced effect, followed by elbow angle and particle size, whereas air pressure has a relatively minor impact. In terms of the pressure drop inside the pipeline, all factors—airflow velocity, elbow angle, particle size, and air pressure—exert considerable influence, with air pressure being the most critical factor. The optimal configuration for minimizing both particle breakage and pressure drop was determined to be an elbow angle of 150°, particle size ranging from 7 to 11 mm, airflow velocity of 20 m/s, and air pressure of 0.4 MPa.

In this paper, the Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) coupling method was used to simulate the pneumatic transport of pebble particles in a three-blade spiral tube. The results showed that the flow field distribution rotated along the circumference after loading. The maximum velocity of the flow field after loading was manifested as rotation along the circumference. In addition, the swirl intensity decreased exponentially with the increase in conveying distance, and the maximum swirl intensity had a saturation value. After reaching the saturation value, it is not evident that increasing the initial air velocity significantly affected swirl variation. The smaller the pitch, the greater the initial swirl intensity. The swirling flow was conducive to the fluidization of particles, but it would bring a significant energy loss. Increasing the swirl can increase the degree of particle dispersion. There is an optimal tangential airflow velocity, which allows the particles to fully spin and stay in the suspension zone without being thrown onto the pipe wall by excessive centrifugal force. At this time, the energy efficiency reaches the highest level. A 5.87 m/s velocity was deemed the optimal tangential airflow velocity for conveying 3 mm particles.

This article studies the influence of structural parameters of the optimization model for the gas–liquid mixing device of a fire truck (compressed air foam lift fire truck, model JP21/G2, made in China) on the liquid phase volume fraction, static pressure, velocity streamline, and the influence of smaller flow rates on the mixing effect. By using the computational fluid dynamics (CFD) software FLUENT 2021 R2, numerical simulations were conducted on the fluid domain model of the gas–liquid mixing device of the JP21/G2 fire truck. The changes in the mixing effect time dimension, liquid phase volume fraction, static pressure, and velocity streamline inside the gas–liquid mixing device were obtained. The optimal mixer structure combination in practical applications was inferred through orthogonal experiments, and the influence of flow rate on the optimal pipe diameter and shortest mixing distance was obtained through variable flow rate simulation experiments. The numerical simulation results show that the presence of bent pipes in the JP21/G2 real vehicle model hinders the gas–liquid mixing process. A straight pipe section of at least 8 m was added after the bent pipe to ensure the mixing effect. The optimal parameter combination for orthogonal experiments had an accurate value of 50°-50°-220 mm. Under the same pipe diameter, using a larger flow rate can achieve better mixing effects.