一、前言 农业物料的空气动力学特性与脱出物的清选和分离,物料的气流输送和谷粒的气流播种等问题密切相关。为了脱出物的清选和分离,必须根据这些混杂物各自的临界速度和清粮室的结构来确定所需的风速。而在气流输送或气流播种中,物料的空气动力学特性也是决定机器性能的主要依据。 I. INTRODUCTION The aerodynamic characteristics of agricultural materials are closely related to such issues as the removal and separation of extrusions, the air transport of materials and the sowing of air currents in cereals. For the removal and separation of effluents, the required wind speed must be determined based on the respective critical velocities of these admixtures and the structure of the grain storage compartment. In the air flow or air sowing, the aerodynamic characteristics of the material is also the main basis for determining the performance of the machine.