In order to reveal the flow characteristics of fluid in rectangular tapered pulp distributor,the velocity and pressure distributions in the rectangular tapered header as well as the mass flowrate distribution out of manifold tubes were investigated based on computational fluid dynamics.Then,three kinds of rectangular tapered headers respectively in simplified type,piecewise approximated type and modified type were comparatively investigated.The results show that there are distinct velocity nonuniformity and pressure gradient along the flow direction in the widely-used simplified header,which results in nonuniform mass flowrate out of the manifold tubes,and that the pressure and the mass flowrate in both the approximated the modified headers are also obviously nonuniform.It is also found that and the mass flowrate distributions in the three headers,which has notable deviation from the expected ones,increase in the order of simplified typepiecewise approximated typemodified type,and that the back wall shape of the rectangular tapered header designed based on the Baines method is greatly different from the expected one.