Simulation Analysis And Optimization Of Wheat Harvester Cleaning Device Based On CFD-DEM Coupling

The combine harvester cleaning unit is an important part of the harvester,and the efficiency of the cleaning directly affects the working performance of the combine harvester.The function of the combine harvester cleaning system separation system is to remove the impurities from the material that has been pressed out of the roll to remove the harvesters.The study of the cleaning device is mainly to analyze the distribution law of the indoor flow field,the law of the movement of the material on the screen surface,and provide the basis for the design and optimization of the cleaning device.The theory and simulation of the cleaning device are carried out by the theory of computational fluid dynamics,discrete element method and gas-solid two-phase flow.The main contents of this paper are as follows:(1)The main components of the material in the wheat removal device include: wheat grain,short stalk,short grass,the main effect of the cleaning effect in the material is short stalk.The morphological characteristics of wheat grain and the mechanical parameters such as density,friction coefficient and recovery coefficient were measured by experiment.Three-dimensional model was established.And the suspension velocity of the main components in the selected materials was measured by the suspension velocity measuring device.The obtained data provided the basis for the subsequent numerical simulation.(2)FLUEN and EDEM software were coupled by API,coupled with Eulerian mathematical model,EDEM using Hertz-Mindlin contact model to simulate the interaction between particles and particles and the screen surface,FLUENT R-NG flow field model simulation The law of airflow velocity and air pressure in the device.The coupling simulation shows that the wind speed of the fan outlet has a large influence on the longitudinal velocity of the airflow on the surface of the fan,and the grain density of the wheat is larger than that of the wheat The effect of the vertical velocity of the stalk is very small.With the increase of the wind speed,the backward speed of the material is improved,which is helpful to improve the processing capacity of the wind sieve cleaning device,but it will increase the grain loss.The grain size of wheat is mainly distributed in the front of the screen surface.With the increase ofthe wind speed of the fan outlet,the grain is distributed after the screen,and the number of grains is very small after the front of the screen surface.(3)The cross-flow fan speed is divided into four variable factors by the inclination of the cross-flow fan,the frequency of the vibrating screen and the amplitude of the vibrating screen.Four orthogonal factors are designed to design an orthogonal test table L16(4 * 4)The CFD-EDEM simulation experiment was carried out to obtain the experimental results.The experimental results show that the speed of the cross-flow fan,the inclination of the cross-flow fan,the amplitude of the vibrating screen and the frequency of the vibrating screen have the same The main influencing factors were wind speed> fan inclination> frequency>amplitude.The parameters were optimized according to the size of the influencing factors and the influencing factors.