Experimental Study And Numercial Simulation Of Air Flow Field In The Cleaning Device Of A Rape's Combine Harvester

The thrashed materials in a Rapeseed Combine Harvester contain many things, andmost of them are impurities, such as long and short stern and stalk, hulls mud and sand.The separation and cleaning of rapeseeds is a very important task for a RapeseedCombine Harvester. The strong or weak strength of the wind and the direction of thewind's entering play a key role in the cleaning and the separation of the rapeseed. If thewind is weak, it will result in some impurities in the seed; if the wind is to strong, it willblow some rapeseeds out of the machine and cause some waste. Therefore, it is highlyimportant and meaningful to do the research on the air flow of the machine. On the basisof the characteristics of the hulls of the Cleaning device of a rapeseed combine harvester,with numerical simulation, the condition of the air current of the selecting machine aremainly studied by using ANSYS in this thesis.According to the experiments, we may know the features of the seed and theimpurities, such as the size of the seed, the impurities' float speed. The conclusion is thatthe differences among the hulls' float speed is obvious on the condition that they containthe same moisture content. Comparatively speaking, the rapeseeds' critical float speed ismuch greater, which gives us the basic theory and practical experiences for the principleof selection device's separation.The Cleaning Device of a Rape's Combine Harvester of 4LZ(Y)——1.5A is taken asstudy object, with the aim at building a math-physics model for its air flow, getting theequation about the controlling air current, scattering them via calculating the flowdifferential equation's limitation. The finite element ANSYS' FLOTRAN model isapplied to the air current with the purpose of numeric simulation. While on the research,the boundary conditions are got from testing, and the distributing information about thespeed are inferred by calculating in the computation domain. Using the model comparingthe simulated results with the experimented data, under believable degree of 0.01 to, it isfound that there is no evident slight difference between the simulative results and theexperiment result, that is to say, the simulative result is valid.In this thesis the related parameters of the air current is studied by using the builtmodel. Through changing the speed of the wind and the wind's entering angle, we getdifferent combined group's flow speed from the calculation under the help of the model.And we use SPSS to analyze some relation ships, among these parameters. And it is found,the wind speed and the wind's entering angle, have great influence on the cleaning device's inner flow speed. (The believable degree is 0.01). The correlated coefficients are0.622 and 0.458; the wind speed does have the greater influence. Meanwhile, using thismodel, the numerical simulation is done for the parameters of this machine. A full arrayedtest of numerical simulation is done for the angle of entrance wind with three factors andwind speed with four levels. Test results show that when the angle of the entrance windβ=25°and the wind speed v=35m/s, on the defined path, velocity component along the ydirection can better meet the requirements of separation.