Flow Field Analysis And Structure Optimization Of Ventilation Pipe Of Suspension Tea Picker

China is a large agricultural country,and the area planted with tea is expanding,However,the picking operations are mostly based on backward manual operations,and the realization of harvest mechanization has become more and more urgent.In recent decades,the introduction of tea pickers from abroad and the self-developed tea picking machines in China have more or less problems such as low picking efficiency,high vibration and low automation,which has hindered the large-scale promotion of the mechanical picking tea market.Therefore,there is an urgent need in the market for a tea picking machine with high picking efficiency,low cost and automation.As the main structure of the tea picking machine,the ventilation duct is used to send out the air volume generated by the fan,so that the tea leaves cut out by the tea pot are blown into the leaf bag.If the outlet speed of the ventilation duct is too small,the tea cut from the samovar cannot be blown into the collection bag;if the exit speed is too large,the tea bud on the samovar will oscillate,and the quality of the tea cut by the blade will be seriously degraded.The motor power increases and wastes resources.Therefore,the research on the internal flow field and structural optimization of the ventilation duct is of great significance to improve the quality and efficiency on tea harvesting.In this paper,the ventilation duct of tea-picking machine is selected as the research object.Use relevant fluid mechanics theory knowledge and FLUNET software to get vector diagram of the internal velocity of the ventilation duct on simulation study.With the goal of minimizing the unevenness of the outlet wind speed of each branch pipe,the parameters of the ventilation duct structure of the tea-picking machine are optimized,which provides a reliable theoretical basis for the optimization design of other parameters of the tea-making machine ventilation duct.The main work of this paper is as follows:1.Based on the analysis of the existing tea harvesting methods,the growth characteristics of machine-harvested tea plants and the technology of machine-harvesting,a single-track suspended tea harvester is designed through research and design.It adopts track structure,motor-driven,automatic walking,and has the characteristics of low cost and low labor intensity.Using the principle of uniform air supply,the overall structure,main pipe and branch pipe of the ventilation duct of tea harvester are studied and designed.The design is carried out and the air pressure and resistance of the ventilation duct are calculated.2.Wheeled anemometer and two-handed tea picker were used as experimental instruments to test the uniformity of wind speed in the ventilation duct of tea picker.Through collecting and analyzing the test data,the unevenness of the branch pipe of the ventilation pipe is 14.09%,which indicates that the velocity of each branch pipe of the ventilation pipe is uneven,so it is necessary to optimize the existing structure of the ventilation pipe.3.Using SolidWorks three-dimensional software to establish the geometric model of ventilation duct,using FLUENT simulation software,the ventilation duct model was meshed,the reasonable turbulence model and solution parameters were selected,and the three-dimensional numerical simulation of the flow field inside the ventilation duct was completed.At the same time,the validity of the three-dimensional numerical simulation of ventilation duct is verified by comparing with the experimental results of evaluating the uniformity of duct wind speed.4.Through single factor test,the influence degree and sensitivity of main wind speed,main taper,branch diameter and branch spacing on the flow field inside the ventilation duct are analyzed,and then the reason of each parameter producing this result is theoretically analyzed.According to the principle and method of orthogonal test,the optimization test table of L₁₆?4⁴?is designed,and the structural parameters of ventilation duct are optimized with the aim of velocity uniformity.After optimization,the structural parameters of the ventilation duct are as follows:the main inlet wind speed is 22 m/s,the main taper is 1:80,the number of branches is10,and the diameter of branches is 15 mm.After optimization,the non-uniformity of branch velocity of ventilation pipeline is 4.32%,which is 9.77%lower than that of original ventilation pipeline,and the optimization effect is very obvious.