Design And Test Of A Pneumatic Precision Metering Device For Wheat

In attempt to avoid the shortcomings of the traditional metering devices used for wheat metering over years, the objective of this study comes in framework of applying the precision seeding approach on wheat metering which can overcome seed damage, seed loss and non-uniform distribution. Accordingly, a prototype of a pneumatic precision metering device for wheat was designed, manufactured and tested under laboratory and field conditions. The performance of the device, including quality of feed index (QFI), multiple index (MULI), miss index (MISI) and seed rate expressed in number of kernels per meter length (KPM), was investigated under laboratory conditions using a test stand with camera system on different working conditions. The laboratory testing was then confirmed by a field experiment.To correlate the theory with the practical findings the factors affecting the seed motion during picks-up, transporting and releasing stages were dynamically analysed. ANSYS-CFX software was also involved to simulate some parameters in order to optimize the structure of the metering deviceThe results revealed that the rotating speed (RS) and negative pressure (NP) and their interaction have a significant effect on variables at1%and5%level of significance. The highest QFI (92.98%) was obtained at rotating speed of19.0rpm and negative pressures of2.5kPa with MULI and MISI of2.01%and5.09%respectively; however, the seed rate (KPM) was less than the recommended, the best seed rate was53KPM yielding QFI of89.11%with MULI and MISI of9.00%and1.88%respectively at rotating speed of34rpm and negative pressure of4.5kPa. The study demonstrated that wheat could be seeding within an acceptable precisely range by pneumatic precision metering device.The results from dynamic analysis were found to be corresponding with that of the laboratory testing. The findings revealed that the performance indices (quality of feed index QFI, multiple index MULI and miss index MISI) were obviously influenced by changing the negative pressure force FQ and rotating speed ω.The result from test stand highlighted that when the negative pressure increased the QFI increased, MULI increased and MISI decreased, however, the QFI decreased and MISI increased with increasing the rotating speedThe dynamic analysis likewise revealed that increasing the friction index tan αg by choosing a suitable material with high friction angle αg for seed plate as well as enlarging the seed hole diameter could improve the efficiency of the negative pressure force FQ.The field experiment exposed a uniform seedling emergence, the average seed spacing (62mm) was almost equal to the real one (64mm) under field operational parameters. The average QFI%was72.25while in some replications85.7%was achieved. The simulation results were found to be in agreement with that obtained from the laboratory test; the most homogeneous pressure was observed to be realized by2.5,3.5and4.0kPa negative pressure while the highest values of QFI%were found to be given by the same levels of negative pressure under laboratory conditions within different range of rotating speed.