Simulation and analysis of movement trajectories of fresh tea leaf particles based on CFD-EDEM coupling

To study the air-suction separation mechanism of fresh tea leaves, this article adopts the coupling simulation method of discrete elements and computational fluid dynamics to conduct numerical simulation and experimental research on the movement of fresh tea leaves adsorbed by negative pressure air flow. In the gas–solid coupling model, three-dimensional scanning technology is applied to establish a three-dimensional model of fresh tea leaves with one bud and two leaves. Through the Fluent module in CFD, the negative pressure adsorption gas phase of the simulation process was established, bench tests were established, and parameters of the coupling model were optimized. Finally, the minimum error between the simulated value and the test value was 2.85% and the maximum error was 7.43%, indicating that the coupling model established had certain accuracy and could be theoretically analyzed according to the coupling model established. It is found that when the static pressure values of the adsorption surface are −120 Pa, −340 Pa, and −500 Pa respectively, the initial distance from the adsorption surface is 250–550 mm. It is found that fresh tea leaves with one bud and two leaves all fall to the pipe before adsorption, and then move to the adsorption surface. Under the same static pressure value of the adsorption surface, the initial falling distance of tea particles from the adsorption surface (250–550 mm) has a linear function relationship with the distance between the turning point and the adsorption surface. When the initial distance between falling tea particles and the adsorption surface is the same, the distance between the turning point and the adsorption surface is an exponential function when the initial position is 250–350 mm from the adsorption surface, and the distance between the turning point and the adsorption surface is a linear function when the initial position is 400–550 mm from the adsorption surface.