搅拌釜的多场协同以及摩擦熵产率分析

Analysis of Multi-Field Synergy and Frictional Entropy Generation in Stirred Kettles

化工搅拌釜是化工工业中广泛使用的重要设备之一,主要用于混合、搅拌、加热和冷却各种液体和粉状物料,以满足生产过程的需求.当前研究使用计算流体力学方法对搅拌釜内的流场进行了三维数值仿真,分析了搅拌桨旋转导致的流动特性;通过压力场与速度场的夹角,探究了化工搅拌釜内的压力场和速度场的协同关系;通过摩擦熵产揭示了搅拌釜内的流动不可逆性.结果表明:当搅拌桨转速为60 r/min时速度场与压力场具有最大平均协同角,平均协同角随着搅拌桨转速的增加而减小,协同角越小,流体的粘性耗散越大,产生的流阻也越大;流场的摩擦熵产主要集中在搅拌桨附近,平均熵产率随着搅拌桨转速的增加呈现指数增加;搅拌桨旋转产生的旋流是沿桨的两侧轴向逐渐增加并衰减的,搅拌桨转速的增加也意味着旋流强度的增加.

Chemical mixing kettles are one of the essential equipment widely used in the chemical industry for mixing,stirring,heating,and cooling various liquid and powdery materials to meet the demands of the production process.The current study conducted a three-dimensional numerical simulation of the flow field inside the stirred kettle using computational fluid dynamics methods to analyze the flow characteristics due to the rotation of the stirring paddle.The synergistic relationship between the pressure and velocity fields inside the chemical stirring kettle was explored through the angle between the pressure and velocity fields,and the irreversibility of the flow inside the stirring kettle was revealed through the frictional entropy generation.The results show that the velocity and pressure fields have the maximum average synergistic angles when the stirring paddle speed is 60 r/min.The average synergistic angle decreases with the increase of the stirring paddle speed,the smaller the synergistic angle is,the larger the viscous dissipation of the fluid is,and the larger the flow resistance is generated.The frictional entropy generation of the flow field is mainly concentrated in the vicinity of the stirring paddle,and the average entropy generation rate shows an exponential increase with the increase of the rotational speed of the stirring paddle.The cyclonic flow generated by the rotation of the stirring paddle is gradually increased and attenuated along the axial direction of the two sides of the paddle,and the increase in the rotational speed of the stirring paddle also implies the increase of the cyclonic flow intensity.