Design And Experiment Of Hydraulic System Based On Direct Step Rooting Machine

Aquatic vegetables are one of the important agricultural crops in China,among which lotus root has the widest planting area and a large consumer population.At present,the development of the lotus root industry is constrained by mechanized production,and the bottleneck of mechanized production of lotus roots is harvesting.This article focuses on the problems of strong labor,low work efficiency,and heavy harvesting machinery during manual harvesting,and develops a direct linked stepper lotus root digging machine.The specific research content includes:(1)Design of the overall structure of the direct step type lotus root digging machine..A systematic analysis was conducted on the current research status of lotus root harvesters and water jet technology at home and abroad.In response to the harvesting requirements of shallow lotus roots in small plots,a general design scheme for a direct step type lotus root digging machine based on engines,sewage submersible pumps,spiral lifting devices,nozzles,etc.was proposed.The working process and principle were explained,and the working width of the entire machine was determined to be 1200 mm and the length was 1525 mm.(2)Conduct selection,structural design,and parameter analysis of key components of the lotus root digging machine,and determine that the engine power is17.1 k W,the sewage pump power is 15 k W,the head is 60 m,and the flow rate is 80m3/h.Calculate the energy loss of the hydraulic erosion system of the lotus root digging machine.Establish an energy loss model for the hydraulic system of the lotus root digging machine,calculate the energy losses along the route and in the local area.Through calculation,it is found that the total hydraulic loss of the hydraulic erosion system of the direct stepping lotus root digging machine is 3.49583 meters,which meets the design requirements.The calculation of the jet strike force and impact pressure of the direct step type lotus root digging machine shows that the jet strike force is 32.7548 N,and the impact pressure is 0.03911 MPa.Both results are far less than the lotus root bearing limit and will not cause damage to the lotus root.(3)Simulation test of key components of the direct step type lotus root digging machine.Using FLUENT software to simulate and analyze the structural parameters of the nozzle,it was found through simulation experiments that the internal fluid velocity of fan-shaped nozzles with different inlet diameters changes rapidly after the inflection point.The larger the inlet diameter,the greater the amplitude of flow velocity change,but the final flow velocity difference is not significant;The internal fluid axis pressure drops rapidly after the inflection point,and finally reaches the minimum value at similar positions.The smaller the inner diameter of the water inlet,the greater the pressure change.Finally,the inner diameter of the rotating nozzle water inlet is 40 mm.Using FLUENT software,simulation analysis was conducted on the cutting angle and depth of the fan-shaped nozzle.Through simulation experiments,it was found that as the cutting angle of the nozzle continued to increase,the flow rate loss rate of the nozzle continued to decrease,and the jet width first increased and then decreased;As the depth of the nozzle groove increases,the trend of flow rate loss rate and jet width change is the same as the groove angle.Considering the actual operational requirements,the final choice of nozzle groove angle is 60 °,and the groove depth is 10 mm.Based on the coupled simulation analysis of EDEM fluent software,the working performance of the nozzle under different working parameters was analyzed.Through orthogonal experiments,it was found that the nozzle erosion angle has a significant impact on the nozzle erosion depth,and the height of the nozzle from the soil surface has a very significant impact on the nozzle erosion depth.The number of nozzle operations has no significant impact on the nozzle erosion.Considering the actual working environment and agricultural requirements,the number of nozzle operations is 6,and the nozzle erosion angle is 45 ° The height of the nozzle from the mud surface is 125 mm.Based on the FLUENT software,three different structures of water separators are simulated and analyzed.Through the simulation,it is found that the shower head type water separator has a good uniformity of water flow division,and its internal fluid stability is also good.(4)Conduct verification tests on the performance of the nozzle.Through experiments,it was found that there is no leakage area when the nozzle spacing is within 200 mm.A three factor and three level Box Behnken center combination design experiment was conducted using the number of nozzle operations,nozzle erosion angle,and nozzle height from the soil surface as experimental factors,and erosion depth as experimental indicators.Through the experiment,the optimal working parameters of the nozzle were determined to be 6 nozzle operations,45 °nozzle brushing angle,and 120 mm nozzle height from the soil surface.The gasoline engine of the lotus root digging machine has poor working stability,and the scouring depth is only applicable to shallow lotus roots.Further improvement is still needed in the future.