Design And Simulation Of Stirring Device Of A Food Waste Sorting Machine Using Computational Fluid Dynamics

The food waste sorting machine can separate the organic matters from food waste by using biological treatment methods.The food waste and microorganism are mixed by the stirring device,and thus the design parameters of the stirring device is a crucial component for the food waste sorting machine.Moreover,the stress of the stirring device should be considered to maintain the machine performance.Therefore,this study focuses on the stirring device of a horizontal low-speed singleshaft food waste sorting machine.Firstly,CFD simulations were adopted to investigate the effects of different parameter of the stirring device on the distribution of turbulent kinetic energy,shear rate,and shear force.Furthermore,considered with turbulent kinetic energy and shear force as the indicators of mixing efficiency,an orthogonal array experiment of four factors and four levels was conducted.The simulation data analysis was carried out through the range analysis in order to evaluate the importance of the factors and determine the optimal combination of the stirring device.Finally,based on the optimization results,the applicable scenarios of the stirring device were determined by fluid-structure interaction simulations and experimental studies.The research findings of this paper are as follow:(1)During the range of the low speeds(0-90 r/min),the average error of the simulation and experimental results is lower than 5%.That means the standard Euler-VOF formulation of the 6)- turbulence model with the sliding mesh method(SMM)can be used to analyze the flow field of the food waste sorting machines.The simulation results are reliable.(2)The single-factor analysis reveals that the number of stirring blades increases to 4and the length of the stirring blade is increased with the larger area of well-distributed turbulent kinetic energy.Moreover,the shear rate and shear force also raise.The decreasing blade angle and blade aspect ratio lead to larger area of well-distribution of turbulent kinetic energy.Furthermore,the shear rate and shear force also increase.(3)Based on the results of range analysis,the ranking of the significance of factors for turbulent kinetic energy and shear force is determined to be as follows: length of the stirring blade(B)> number of stirring blades(A)> blade angle(C)> blade aspect ratio(D).The optimal combination of the stirring device for turbulent kinetic energy is A4B4C2D3 and the optimal combination of the stirring device for shear force is A4B4C2D2.(4)According to the results of fluid-solid coupling simulations and experimental studies,the optimal combination of the stirring device for shear force is suitable for the mixing materials with the high viscosity.The optimal combination of the stirring device for turbulent kinetic energy is appropriate for dealing with a large volume of mixing materials or a high rotational speed of the machine.