The Flow Field Numerical Simulation And Test And Structure Optimization Of Main Grain Cleaning Equipments

With the increase of grain harvest mechanization in China, the impurities in grain especially wheat straw segment, corn cob fragments, etc. increased seriously. After grain harvest is no effective supporting clean technology and equipment, resulting in a substantial grain of impurity rate rise. After harvest without valid supporting clean technology and equipment, commodity grain impurity rate increased significantly. As grain contains a lot of straw and chaff, it is extremely easy to fever, pollution, mildew and pest during storage, which directly caused grain losses even reached around 6%, great impact on downstream grain processing and the quality of products, increases the cost of processing enterprises. Solving the problem of grain harvest clean-up lag safely and efficiently, cleaning up the harvest grain directly, removing impurities, and making grain impurities(large, medium and miscellaneous) content in line with the current requirements of the relevant national standards are very urgent.This paper was based on my responsible part in the project, cereal winnowing sieve theory and fluid dynamics, and focused on different aerodynamics of different materials. I use FLUENT software for numerical simulation of the internal flow field of grain cleaning equipment. The results of simulation studies have been carried out and eventually the equipment was improved. The equipment of different air speed optimization parameters corresponding to the field, velocity vector, the airflow velocity contours, streamline and pressure field were compared by single factor method, in order to determine the optimal parameters. And the reliability of the result is verified by experiment. finally the equipmen was designed and drew again.TFDZ-100 vibrating aspiration channel internal flow field was investigated through numerical simulation. The simulation results of 64 monitoring points of measured wind speed in comparison with the results. The absolute error up 1m/s accounted for more than 6.25% among the monitoring points, monitoring point of absolute error up 0.5m/s accounted for 37.35%, the rest were less than 0.5m/s. To verify the simulation model, set the boundary conditions, the numerical algorithm, calculation model, the correctness of the solution and analysis results In the left side of the winnowing stable region, there was a winnowing blind, where its airflow speed was 0 m/s or even reverse. The thickness of vibrating aspiration channel winnowing room has the most important influence on flow field distribution and screening efficiency. In the case of appropriate amount of wind, the winnowing room thickness of 120 mm is an optimum result. The length of feed inlet is also an important factor which influences the flow field distribution of stable winnowing region. Analysis indicates that inlet length is smaller, winnowing flow field distribution is more reasonable. The optimum length of inlet is 70 mm with the consideration of actual working conditions. In winnowing room separation area,there is a large scale scroll area. Adding a board under the air inlet will eliminate eddy current conditions, increase airflow working thickness of separation area, improve separation efficiency and reduce energy consumption.To TQLZ100×200.0 Linear Vibrating Screen, analysis shows that its internal air flow motion is more complicated and air speed is lower. Feed bins and wheat exports are the main parts where producing pressure loss. As the air inlet the angle of linear vibrating screen and complicated structure, screen exists in a wide range of eddy current, we propose to eliminate a wide range of eddy current and reduce the pressure losing.To TSCY85X150 single cylinder cleaning sieve, the air outlet is the main part of producing pressure drop. This research studies the influence of different size of air outlet to partial pressure loss of equipment. Optimization the air outlet nozzle diameter to the present equipment, To the present equipment, De=200mm is a better result. the partial pressure P could be reduced by 103.4Pa.