A tumbler screen-type residual film–impurity mixture wind separator is the key equipment for the secondary utilization of farmland residual film. During its operation, the proportion of impurities in the separated waste mulch film intermittently increases, resulting in poor working stability of the device, which may hamper long-term operation. To address the above issues, the material inside the separation unit was continuously monitored, and the main factor affecting separator performance was determined to be the challenges in the effective depolymerization of some residual film-impurity mixtures. The principles of agglomeration and depolymerization of the residual film-impurity mixtures were analyzed using computational fluid dynamics (CFD) and discrete element method (DEM) flow-solid coupling simulation methods. The key factor affecting the disaggregation of the mixture was the collision force between the residual film–impurity mixture and the trommel screen. The collision force was maximum when the residual film–impurity mixture first collided with the trommel screen when it was fed into the separation device. Furthermore, simulations were carried out for different inlet structure forms; the evaluation index was the maximum collision force of the residual film–impurity mixture agglomerate on the trommel screen. The best disaggregation effect was obtained with a square feed inlet and at a feeding rate of 202 kg/h. A prototype was built using these specifications for verification. The average value of the ratio of impurities in the residual film was 6.966%, the coefficient of variation was 7.38%, and the dispersion of statistical results was small. The ratio of impurities in the residual film was kept constant during the continuous operation of the wind separator. Thus, in this study, we analyzed the agglomerate disaggregation process and provided theoretical insights for determining the optimal structures of the inlets of various cleaning devices and the feeding volumes.

The airflow velocity in some nozzles is low, and the clearing of the nozzle is ineffective because of unreasonable airflow pipe arrangements and the distance from the nozzle to the screen surface of screen-hole-clearing devices for trommel-sieve-type residual film–impurity wind separators. In the present study, the main structure and working parameters affecting the screen hole clogging situation were determined through theoretical analysis and computational fluid dynamics simulations. In addition, a three-factor, three-level quadratic regression orthogonal center of rotation combination test was performed. The distance from the nozzle to the screen surface, fan wind speed, and the number of airflow pipes were selected as test factors, and the ratio of impurities in the residual film and the blockage ratio of the screen holes were selected as the evaluation indexes. The results indicated that the ratio of impurities in the residual film was reduced by 2.42% and the blockage ratio of the screen holes was reduced by 1.92% at a nozzle-to-screen distance of 102 mm, a fan wind speed of 24 m/s, and with four air pipes. The resulting impurity ratio in the film was 5.86%, and the blockage ratio of screen pores was 5.41%. The minimum airflow velocity of 15.8 m/s at each nozzle position of the optimized screen-hole-clearing device satisfied the requirements of screen hole clearing and blockage. Furthermore, the ratio of impurities in the residual film and the blockage ratio of the screen holes remained unchanged during the continuous operation of the device. This indicated that the optimized screen-hole-clearing device had a stable working performance. This study may provide a theoretical framework for the future development of screen-hole--clearing devices.

A tumbler screen type residual film–impurity mixture wind separator as a key equipment for secondary utilization of farmland residual film. During the working process, the proportion of impurities in the separated waste mulch film intermittently increases, resulting in poor working stability of the device, which may hamper long-term operation. In this study, the material inside the separation unit was continuously monitored, and the main factor affecting separator per-formance was determined to be the challenges in the effective depolymerization of some residual film–impurity mixtures. The principles of agglomeration and depolymerization of the residual film–impurity mixtures were analyzed using computational fluid dynamics (CFD) and discrete element method (DEM) flow-solid coupling simulation methods. The key factor affecting the disaggregation of the mixture was the collision force between the residual film–impurity mixture and the trommel screen. The collision force was maximum when the residual film–impurity mixture first collided with the trommel screen when it was fed into the separation device. As determined by force analyses, the key factors affecting the collision force of the process were the material feeding amount and the structure of the inlet. Furthermore, simulations were carried out for different inlet structure forms; the evaluation index was the maximum collision force of the residual film–impurity mixture agglomerate on the trommel screen. The best disaggregation effect was obtained with a square feed inlet and at a feeding rate of 202 kg/h. A prototype was built using these specifications for verification. The average value of the ratio of impurities in the re-sidual film was 6.966%, the coefficient of variation was 7.38%, and the dispersion of statistical results was small. The ratio of impurities in the residual film was kept constant during the con-tinuous operation of the wind separator. Thus, this study analyzed the agglomerate disaggregation process and provided theoretical insights for deter-mining the optimal structures of the inlets of various cleaning devices and the feeding volumes.

Aiming at the problem that rotary tiller knife rollers are prone to entanglement with straw in the wet and sticky soil environment of rice fields in the middle and lower reaches of the Yangtze River in China, an antitangling and sticking cutter was designed. The cutter reduces knife roller entanglement in order to reduce rotary tiller energy consumption and improve work efficiency, and its effectiveness was verified through theoretical analysis, discrete element simulation, and field trials. The design’s validity was verified through theoretical analysis, discrete element simulation, and field tests. The blade inclination design was completed through motion force analysis, and the tool geometry was optimized with a 36.87° inclination baffle and staggered arrangement. A simulation model of the soil–straw–rotary tillage knife interaction was established and we used the discrete element method to analyze the variation in torque between the antisticking knife and the China standard rotary tillage knife (IT245) at four different cutter shaft rotational speeds. In the simulation, the average torque for the antisticking knives was smaller than that of the national standard rotary tillage knives, with reductions of 37.1%, 52.1%, 52.8%, and 50.0%, respectively, demonstrating a remarkable effect. Field tests showed that the average operational efficiency of the antisticking knife was 0.57 hm²/h, with an operation qualification rate of 95.72%. The average torque results from simulation (with and without the antisticking knife) and field tests were analyzed, yielding correlation coefficients of 0.994 and 0.973 for the change curves of average torque between the antisticking knife and the national standard rotary tillage knife. This result confirms the accuracy of the simulation model and the consistency between the simulation and field test results. This study can provide some references for the design and test of antisticking of rotary tillers.