孔板布浆器广泛用于中高速纸机流浆箱,为使其布浆流动更高效均一,需将分布元件内的涡流效应进行最小化设计。利用UG建立局部流场模型并利用CFD进行模型网格划分,然后导入FLUENT软件进行流体分析; 比较了台座式和无台座式两种孔板孔结构下的流体特征,获得流场的压力、湍流动能以及速度的分布云图等数据图。结果表明:在选取布浆口流速3 m/s、孔口直径14 mm、相邻孔间距40 mm条件下,台座式以及单孔入口处的有倒圆角的孔板孔口涡流效应明显减弱,而浆流动效率相对提高,且随着倒圆角半径增大,这种作用更加明显; 对于多孔板而言,当倒角半径增至1.5 mm时,相邻孔之间的影响较小,纸浆流体形态最好,浆料分布最均匀,较结构改进前的流动效率提高了125.78%。
Abstract
The tapered distributor with orifice plate is widely used in high speed paper machines. In order to make uniform and efficient fiber flow from the distributor into the head box, the vortex near the entrance of the orifice must be eliminated or reduced. The local flow field model of the tapered distributor was firstly drawn with UG software. The grid division was then established with computational fluid dynamics(CFD)method, and the flow field was subsequently simulated with the FLUENT software. Flow characteristics of the tapered distributor with a pedestal shape hole and a straight shape hole were obtained and compared with respect to the distribution contours of the pressure, turbulent kinetic energy, and velocity magnitude in the orifice model. The simulation results showed that, under the experimental condition of 3 m/s pulp flow velocity in distributor, 14 mm diameter of entrance hole and 40 mm diameter of pitch of holes, the vorticity of the flow decreased significantly and slurry flow efficiency increased relatively for the tapered distributor with a pedestal shape hole and round chamfering at the entrance. As the chamfering radius increased, the flow quality improved accordingly. For the multi-hole plate, when the chamfering radius increased up to 1.5 mm, the flow interference between the adjacent holes was the smallest and the most uniform pulp flow distribution was obtained. The pulp fluid condition was the best in this case and the flow efficiency increased by 125.78% compared with that of the straight hole structure. The simulation results of the flow field distribution contour can provide a numerical basis for the improvement of the performance of the tapered distributor with the orifice plate.
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基金
基金项目:江苏省制浆造纸科学与技术重点实验室开放基金项目(201522); 江苏高校优势学科建设工程资助项目(PAPD)
第一作者:杨帅(952633368@qq.com)。
*通信作者:张辉(zhnjfu@163.com),教授。
引文格式:杨帅,刘钰,何晶,等. 孔板式锥形布浆器孔口均一性布浆的结构优化[J]. 南京林业大学学报(自然科学版),2016,40(6):141-147.
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