Mathematical Model And Dynamic Characteristics Study Upon Bulk Materials Flow

The surge bin is an important component of accurate, rapid and intelligent loading system. Conducting the thorough research to the coal flow state within the surge bin is of great significance to control the loading accuracy and improve the loading efficiency. According to the special nature of the bulk material flow state, this paper simulates the whole loading and unloading process from the microscopic point using the Particle Flow Code (PFC3D), which is based on the theory of discrete element method, analyzes the flow state of the coal and the changes of velocity field and force field during the discrete process, and analyzes the effects of friction coefficient, particle size, cone inclination and other factors on the mass flow-rate.By the triaxial-text and drop text, the microscopic parameters required for the model and macroscopic mechanical parameters are calibrated. The microscopic parameters established can reflect the expected macro-physical and mechanical behavior.Particle flow code (PFC3D) is used to establish a microscopic model of discrete element of the material flow in the surge bin, we can obtain the changes of the flow state, the velocity field and the force field of coal throughout the discharge process. There is a research that the flow of coal particles within the surge bin belongs to the mass flow, it can ensure the continuous discharge. The particles in the same horizontal plane are rendered uneven settlement, velocity of particles closed to the axis is much larger. It forms dynamically changing pressure arch near the discharge port, the entire discharge process is the formation and destruction of the pressure arch process.In the discharge process, the relationship between mass flow and time is near the linear. The mass flow-rate has a short-term acceleration when the gate is open, then the mass flow-rate is in the stable flow period, it basically revolves around a constant value. The constant value is said to be the slope of the line, which is the relationship between mass flow and time. This paper also gives the computational formula of the mass flow-rate in each discharge state.Through the numerical simulation, this paper analyzes the influencing factors of the particle flow. The mass flow-rate decreases with the increase of the friction coefficient of the particles and bin walls; When the particle size is uniform, the larger the particle size is, the smaller the mass flow-rate is; When the particle size is a certain distribution width, the wider the distribution is, the faster the mass flow-rate is; When the other situations are the same, the larger the cone inclination is, the faster the mass flow-rate is.