# Optimization of Screen-Hole-Clearing Devices for Mechanized Residual Film-Impurity Separation  
[PERSON]  
1 College of Mechanical and Electronic Engineering, Shandong Agricultural University, Taian 2 The mechanism of airflow blockage clearing has been investigated by previous studies. Various studies have developed methods to evaluate the impact of airflow in solving the blockage problem; these methods have been useful in various fields. [PERSON] et al. analyzed the fluidization and transport characteristics of particles by varying the frequency, speed, and flow rate of airflow pulsation, and obtained a suitable sorting medium for fine-grained coal [8]. [PERSON] proposed a variable-diameter pulsating airflow sorting technique for sorting pulverized coal and demonstrated the effects of the air volume and handling capacity on the flow field and sorting effect through numerical simulations and experiments [9]. [PERSON] used high-speed airflow, which had a strong impact and expansion force that destroyed the original static equilibrium of the ore in the bin, eliminated the phenomena of bonding and blockage, and caused a smooth flow of the material in the lower ore opening and the lower ore hopper [10]. [PERSON] simulated the grain cleaning process and analyzed the movement state and movement law of grains in the airflow using a mathematical model of the material and airflow; they also determined the optimal combination of parameters for the cleaning device [11]. [PERSON] performed three-dimensional numerical simulations to analyze the influence of each factor of the vibrating screen surface on the grains in the airflow field, to optimize the influence of an uneven airflow field in the screening device on the grain during the screening process, and to improve cleaning quality [12]. The method of airflow impact dredging is extensively used to alter ores, silos, material tubes, and other static conditions to eliminate granular material blockage. However, the residual film-impurity wind separator of the trommel screen has a rotating state, airflow direction, and screen hole blockage position, and the changes in these characteristics are always relative. The motion of the residual film-impurity mixture is not only constant but also nonlinear. To assess the impact on the performance of blockage clearing, the motion of the mixture should be investigated theoretically and by evaluating the airflow size, distance between the nozzle and the screen surface, airflow pipe arrangement form, etc.  
In the screen hole blockage clearing device for the residual film-impurity wind separator, the airflow pipe arrangement and nozzle end distance from the trommel sieve are unreasonable and cause low airflow speeds in part of the nozzle, ineffective clearing of blockages, and other problems. In the present study, through theoretical analysis, numerical simulations, three-factor three-level quadratic regression orthogonal combination tests, etc., to optimize the structural parameters of the screen hole cleaning device and to determine the optimum number of airflow pipes, distance between the nozzle and screen surface, and fan wind speed. Consequently, the blockage clearing effect of the screen hole blockage clearing device improved, thereby ensuring the reliability of the residual film-impurity wind separator. This study can serve as a theoretical framework for the optimization of screen hole cleaning devices.