Research On The Screening Mechanism And Performance Optimization Of Particle Swarms In Microgravity

The global "moon fever" is heating up again,and human engineering construction such as lunar base construction and mineral resource development has become an important task and an inevitable trend in deep space exploration at this stage.However,the dynamic performance of particulate matter in lunar microgravity is quite different from that in conventional gravity field.Many researchers have discussed the screening mechanism of different vibration modes and structural modes of vibrating screen under conventional gravity.There are few studies on the sieving mechanism of particle groups in lunar microgravity.Therefore,in order to improve the existing functional screen model,it is not suitable for sieving in lunar microgravity.In this study,a functional sieve model with double-layer reverse linear motion in the form of intermediate feeding was established based on the discrete element method,and the screening efficiency and screening time were used as two key indicators to evaluate the performance of the sieve.The screening mechanism of particle swarms under lunar microgravity is preliminarily explored,and an evaluation model for screening machine parameters and comprehensive screening performance is established.The specific research contents and conclusions are as follows:(1)Based on the discrete element method,the numerical simulation of the screening process of the traditional single-screen functional screen was carried out,and the motion characteristics and screening behavior of the particle group on the screen surface were comprehensively analyzed.Aiming at the problem of poor comprehensive screening performance of single screen plate sieve under the lunar gravity field,a functional screen model with double-layer auxiliary screening which can improve the uniform screening of particle groups is established.(2)For the six main screen parameters of the double-layer auxiliary screening function screen machine: vibration frequency,amplitude,vibration direction angle,screen surface inclination angle and plate spacing are the six main parameters for screening performance research.Among them,the three factors of vibration frequency,amplitude and vibration direction angle include two attributes,namely the proportional change of the upper screen plate and the lower screen plate and the proportional change of the lower screen plate and the upper screen plate.The single factor experiment was used to further reveal the influence of the values of various screen parameters on the screening performance,which provided parameter guidance for exploring the performance optimization and optimal parameter combination of the functional screen.(3)Valid screening data based on discrete element method numerical simulations.After the BP neural network based on genetic algorithm establishes the prediction model of screening efficiency and screening time with high accuracy,the screening performance of the functional screening machine is optimized by using multiobjective genetic algorithm.The reliability of the optimization results is verified by numerical simulation experiments.(4)Through the magnetic gravity compensation method,the Helmholtz-Maxwell coil is used to simulate the force of particles in the lunar microgravity field.Based on the principle of binocular stereo vision,the vibration parameters of the pneumatic vibrator are obtained,and then the discrete element method is used for simulation verification.The experimental results show that the numerical simulation of the particle swarm screening mechanism in lunar microgravity based on the discrete element method has certain reliability.