| Tef is the main traditional grain crops in Ethiopia.At present,the cultivation of Tef mainly relies on human and animal in Ethiopia.In this way,the labour intensity is large,the work efficiency is low,meanwhile the quality of sowing is poor that effect the yield.it is difficult to meet the growing demand for Tef.A kind of pneumatic conveying Tef seeder is going to be designed to solve the problems in the process of planting Tef.The pneumatic conveying seed-metering system is the core component of the seeder.This paper mainly focuses on the pneumatic conveying seed-metering system of the seeder.The main research contents and conclusions are as follows:1 The physical properties of the Tef seeds were measured through the measurement test.Some parameters were obtain that:the average of the long axis of the seeds was 1.14mm,the average of the short axis was 0.73mm,equal volume equivalent diameter was about 0.85 mm,mass of 1000 seeds was 0.34 g,bulk density was 863.57 g/L,seed bulk density was 1242.71 g/L,angle of repose was 38.7°,roll stability angle was 22.07°.2?The important components of the pneumatic conveying seed-metering system were identified basing on the research status and actual demand,which including the fan,the seed box,the centralized seed metering device,the injector,the elbow,the honeycomb duct and the distributor,etc.The structural parameters and working parameters of each component of the pneumatic conveying seed-metering system were obtained by calculating the physical properties parameters of the Tef seeds.3?Based on ANSYS-Fluent software,the simulation of the internal multi-phase flow motion of the pneumatic conveying seed-metering system was carried out.With some structural parameters are adjusted and improved,the results showed that the variability coefficient of evenness of feeding rate between rows was 4.71%.According to the national standard of no-tillage seeding drill for the grass,it can meet the requirement of consistency of the row seed quantity,we preliminarily determined that the design of each component part of the pneumatic conveying seed-metering system is determined was reasonable.4?Completed the manufacture of all parts by using machining,3D printing and other technical means.After some adjustment and improvement,the construction of the test bench was completed.By using the test bench to complete the verification test of simulation,the results showed that the variability coefficient of evenness of feeding rate between rows was 5.37%,which proved that the simulation results were credible and it is feasible to study the pneumatic conveying seed-metering system by using the CFD simulation method..5?Box-Benhnken Design(BBD)response surface method was used to design the tests.An orthogonal rotary combination experiment was conducted with the airflow velocity in blower outlet and seed count of centralized air-seed metering device as two independent factors,as well as stability of total flow rate and consistency of each-line flow rate as two dependent indices.Design-Expert software was employed to analyze the test results.The results indicated that at a airflow velocity of 24.19m/s and a flow rate of 5.59g/s,the variability coefficient of seeding stability of sums rows was 0.99%,and the variability coefficient of evenness of feeding rate between rows was 4.98%.Experiments was carried out with the optimal parameters,and the results showed that the variability coefficient of seeding stability of sums rows and the variability coefficient of evenness of feeding rate between rows were 1.02%and 4.87%,respectively,which were basically in accordance with the optimized prediction results,it proved that the optimization process and results were correct.6?The Tef seeder was designed and developmented based on the pneumatic conveying seed-metering system.The results of field testing showed that the variability coefficient of seeding stability of sums rows was 1.27%,and the variability coefficient of evenness of feeding rate between rows was 4.91%. |
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