Design And Experiment Of Pneumatic Double-side Fertilizer Devices For Ratoon Rice

Fertilization is an indispensable link to increase the yield of food crops,and it is an important guarantee for achieving high yield,high efficiency and food security in agriculture.However,unreasonable fertilization will lead to crop yield reduction and environmental pollution.Ratooning rice is one of the food crops to improve the multiple cropping index and increase farmers'income.At present,there are some problems in the top dressing of ratooning rice,such as low uniformity of fertilization and unstable fertilization rate in top dressing,which cause fertilizer waste and affect the yield of ratooning rice.Therefore,in order to improve the uniformity of fertilization and the stability of fertilization rate,a kind of pneumatic double-side fertilizer device was designed.The key components of fertilizer device were studied by theoretical analysis,simulation analysis,experimental research and other methods.The research contents are as follows:?1?Determination of the material characteristics on fertilizer.The length,width and thickness of granular compound fertilizer were measured.And the size distribution rule of granular compound fertilizer was analyzed.The sphericity of fertilizer was calculated.The moisture content,1000 grain weight,natural angle of repose,real density and bulk density of fertilizer were obtained.The coefficient of sliding friction and the collision recovery coefficients between fertilizer particles and fertilizer particles,plastics and steel plates were obtained.This study provides the basis for the structure design,simulation parameter setting and experiment of the double-side fertilizer device.?2?The design of the pneumatic double-side fertilizer device for ratooning rice.The fertilizer feed system consists of fertilizer box,fertilizer apparatus and motor,and the pneumatic fertilizer conveying system consists of fan,air inlet pipe,fertilizer mixing pipe and fertilizer distributor.?1?The improvement of fertilizer feed device in fertilizer feed system.This paper designs a fertilizer aparatus of staggered spiral adjustable outer grooved wheel,and determines the key parameters of the fertilizer aparatus:the radius r of the fertilizer aparatus grooved wheel is 35 mm,the maximum working length L of the grooved wheel is 50 mm;the number Z of grooves is 8,and the radius r of the end circle of the grooved is 10 mm;the theoretical single circle fertilizer exhausting amount under different working length is calculated;the spiral rising angle is obtained by using MATLAB software analysis;the software concludes that 34.4°?80.2°is a suitable range;the mechanical analysis of the filling process of fertilizer particles was carried out,and the functional relationship between the time t required for the filling of fertilizer particles into the fertilizer groove and the mass m of the fertilizer particles,the friction coefficient?₁between the fertilizer particles and the angular velocity?of the fertilizer groove wheel was obtained.?2?The design and analysis of key components in pneumatic fertilizer conveying system.Through analysis and calculation,the key parameters of the fertilizer mixing device are obtained:the inlet wind speed is 25 m/s,the inlet pipe diameter D₁is 45 mm,the contraction angle?of the contraction pipe is 21°,the diameter D₃of the gas fertilizer mixing chamber is 31.5 mm,the length L is 31.5 mm,the expansion angle?of the expansion pipe is 8°,and the diameter D₂of the fertilizer transmission pipe is 38mm.Through the structural design and analysis of the fertilizer distributor,it is concluded that the angle?of the fertilizer distributor will affect the air flow and the uniformity of fertilization on both sides,and the distance between the two rows of fertilizer outlets should be less than 20 cm.?3?FLUENT-EDEM coupling simulation.Combined with the characteristics of fertilizer particles,the key components of pneumatic fertilizer conveying system are simulated by FLUENT-EDEM.Fluent software is used to analyze the gas-phase flow field,edem software to analyze the force status of fertilizer particles in the gas-phase flow field.The continuous equation,momentum conservation equation and motion balance equation of the solid phase are established.Euler-Lagrange method is used to simulate the coupling of the fertilizer mixing device.The pressure nephogram and velocity vector distribution diagram of the fertilizer mixing device are obtained.It is concluded that inlet velocity of air flow has little effect on the distribution of static pressure.When the inlet velocity of air flow is 15 m/s,20 m/s,25 m/s,30 m/s,the maximum velocity of air flow in the fertilizer mixing device is 42.94 m/s,58.28 m/s,62.96 m/s,107.34 m/s,respectively;the venturi structure of the fertilizer mixing device can promote the mixing of fertilizer particles and air flow.The location and track distribution of granular fertilizer in the fertilizer mixing device were analyzed.It was found that with the increase of the inlet wind speed,the impact between the fertilizer and the wall of the expansion chamber decreased,and the transport of fertilizer particles was more stable.The optimal inlet air velocity was determined to be 25m/s by combining with the design part.It provides the basis for the next part of the test.?4?Experimental study.In order to explore the main influencing factors and the changing law of the fertilization performance of the pneumatic double-side device for ratoon rice,and to provide the experimental basis for the field test of the fertilizer device,the bench test,the orthogonal combination test of the fertilizer feed device and the air delivery device were carried out.?1?In the performance test of the fertilizer feed device,when the working length of the groove wheel is kept constant and the rotating speed is 10 r/min,20 r/min,30 r/min,40 r/min and 50 r/min respectively,the fertilizer discharging performance of the fertilizer discharging device will change.The variation coefficient of the single circle fertilizer discharge of the grooved is 3.18%at the maximum and 1.02%at the minimum;the theoretical value is close to the actual value of the single lap fertilizer;the regression equation between the working length and the amount of fertilizer discharged in a single circle is established.By conducting comparative tests,it is shown that the staggered spiral groove fertilizer apparatus has better uniformity of fertilizer discharge than the traditional fertilizer apparatus.?2?The single factor test of the fertilizer distributor in the pneumatic fertilizer conveying system shows that with the increase of the angle of the fertilizer distributor total quantity of the fertilizer discharging stability coefficient of variation and row fertilizer quantity consistently coefficient of variations decrease first and then increase;when the angle of the fertilizer distributor is 180°,there is no diversion of the angle of the fertilizer distributor,and the fertilizer particles are detained,and the uniformity of fertilizer discharge is greatly affected.?3?The quadratic regression orthogonal rotation combination experiment shows that the factors affecting total quantity of the fertilizer discharging stability coefficient of variation were the rotation speed,the working length,and the angle in sequence.The factors affecting row fertilizer quantity consistently coefficient of variations were the rotation speed,the angle,and the working length in sequence.The optimal parameter combination is determined by Design-Expert software with the rotation speed of 16 r/min,the working length of 22 mm,and the angle of 114°.Under the optimal parameter,the total quantity of the fertilizer discharging stability coefficient of variation and the row fertilizer quantity consistently coefficient of variations were 1%and 2.45%,respectively.The fertilizer device could met the requirements of ratoon rice dressing.