负压差散体颗粒无约束屈服强度实验测量方法

AN IMPROVED METHOD FOR MEASURING THE UNCONFINED YIELD STRENGTH OF POWDERS AGAINST NEGATIVE PRESSURE DROP

根据Ｇｅｌｄａｒｔ－Ａ类散体颗粒在移动床充气条件下气体均匀分布的特点，结合散体力学和两相流理论，提出理论模型并导出散体颗粒的无约束屈服强度与静态拱宽度的关系式，通过实验测量在负压差条件下与移动床立管联接的料斗中Ｇｅｌｄａｒｔ－Ａ类散体颗粒的静态拱宽度来计算其无约束屈服强度．对于Ｇｅｌｄａｒｔ－Ａ类散体颗粒，此方法的测量结果比Ｊｅｎｉｋｅ测量结果能更准确地描述散体颗粒的无约束屈服强度．

For Geldart-A powders featuring uniform gas distribution, a model is presented to delineate the relation between the width of static arching and unconfined yield strength of powders based on the theories ofparticulate media mechanics and non fluidized gas-solids flow. The unconfined yield strength of powders was calculated through measuring the width of static particle arching in the hopper connected to the moving bed under negative pressure drop. The method is especially advantageous for the Geldart-A type particles, whose shear stress under very low normal stress is not large enough to be determined by the Jenike method.