Dissertation > Agricultural Sciences > Agricultural Engineering > Agricultural machinery and implements > Harvesting machinery > Grain,wheat combine harvester ( Awn )

On the Simulant Research of the Pneumatic Cleaning Mechanism of Mini-combine Harvester

Author LiYinHai
Tutor DingQiShuo
School Nanjing Agricultural College
Course Agricultural Engineering
Keywords pneumatic cleaning Mechanism the flow field of cleaning Multiphase numerical simulation
CLC S225.3
Type Master's thesis
Year 2008
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China is a main agricultural country, and combine harvester is widely used in agricultural production. Mini-combine harvesters are the most suitable farm machines for the wide regions of south China, and its’marketing demand is prospective. But due to the restriction of size and construction, most mini-combine harvesters are not equipped with, grain cleaning mechanisms, which results into high ingredients in harvested grain. Therefore, depending on the real demand from the south China agricultural production, a new type of pneumatic cleaning mechanism is designed for the mini-combine harvester for the improvement of grain cleaning performance.Various type of grain cleaning methods and mechanisms were first analyzed and compared, and the construction and performance of each mechanism were identified. The benefit of pneumatic cleaning is then proposed. By further studying the basic physical characteristics of grain seed and pneumatic cleaning, the grain cleaning mechanism and the technologies for the mini-combine harvester is decided.Second, combining the designing demand of pneumatic cleaning mechanism, the reasonability of applying FLUENT software for the simulation on pneumatic grain cleaning mechanism is analyzed, and then explained the details of the FLUENT software, such as its construction, steps of calculation, the network separation, pressure-velocity coupling, RNG k-εmodel, volumetric integration of multi-phase pneumatic flow, and the construction of based on Euler model of the balancing function of pneumatic cleaning.The third part of this work include the construction of 2D and 3D parametric model based on UG, transferring of 2D model into GAMBIT module, transferring the network into FLUENT and performing checking, setting the boundary condition, discrete mode and the pressure-velocity coupling mode, and the construction of the flowing field of cleaning, which realized the separation of grain seed from ingredient and getting related data of simulation.The static iso-pressure tomography, phase picture of grain, velocity tomography, scalar speed diagram, exit distribution of ingredient and the exit distribution of grain seed picture were calculated for the pneumatic cleaning mechanism, which proved the expected performance of the pneumatic cleaning mechanism for the mini-combine harvester.

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