Simulation Analysis And Experiment Of Airflow Field Characteristics Of Alfalfa Mower Conditioner

In order to improve the auxiliary harvesting role of airflow field of alfalfa mowerflattening machine and the quality of alfalfa harvesting,the airflow field simulation model of cutter and flattening roller was built by using CFX fluid simulation software based on the study of the aerodynamic characteristics of alfalfa plant.Simulation analysis and optimization of alfalfa mower-flattening machine airflow field characteristics were carried out,and a test stand was built to study the effect of mower-flattening machine airflow field on the movement of alfalfa plants,the main research work and conclusions are as follows.(1)Aerodynamic tests on alfalfa were conducted,and the results showed that the suspension velocity of all components of alfalfa decreased with the decrease of water content,and there was a linear relationship between suspension velocity and water content;With the variation of water content between 10% and 70%,the suspension velocity of alfalfa leaves varied in the range of 1.34-2.21 m/s,alfalfa stalks in the range of 4.01-6.85 m/s,and alfalfa plants in the range of 3.72-6.69 m/s.(2)The orthogonal simulation tests were carried out by constructing a simulation model of the airflow field around the cutter.The results showed that the optimal airflow field parameters were 7.5814 m/s lifting air velocity,11.4379 m/s feeding air velocity,and 4.1857m/s gathering air velocity when the structure and operating parameters of the cutter were 2000r/min,8° blade twist angle,4° cutting table tilt angle,and 4 pieces of grass guide plates.The mathematical regression model of the airflow filed parameters was built,which could predict the simulated and measured results of the airflow field around the cutter well.(3)The effects of the flattening roller type,rotational speed and flattening roller gap on the characteristic parameters of the airflow field around the flattening roller were studied by constructing a simulation model of the airflow field around the flattening roller.A regression model of the airflow velocity was constructed based on the simulation test results.Compared with the measured values of the prototype,the errors of the regression model in predicting the average airflow velocity around the single-roll,the maximum airflow velocity and the forward airflow velocity the two-roll were 6.35%,4.56% and 5.86%,respectively.(4)The effect of the airflow field on the movement of alfalfa plants was studied by building an alfalfa mower-flattening machine airflow field test stand.The results showed that the airflow field of the mower-flattening machine has the effects such as gathering,lifting and feeding on alfalfa plants,which can assist in harvesting and reduce re-cutting,and the force of the feeding airflow and the gathering airflow on the alfalfa plants were 0.0215 N and 0.04354 N,respectively.