穿流型搅拌器开孔位置的数值模拟

为进一步降低能耗，确定开孔位置对穿流型搅拌器的搅拌效果的影响，在相同的开孔尺寸及开孔率条件下，对八种不同开孔位置的穿流型搅拌器的搅拌流场和功率特性在液一液相条件下对相应搅拌进行了数值模拟．模拟过程中，开孔位置分为近端、中间和远端三种类型，均匀分布在对应的位置；整个搅拌釜分为动静区域，将搅拌轴、搅拌器及其周边区域都设为动区域，剩余区域为静区域进行模型简化处理，基于四面体网格对模型进行网格划分，选用标准k—e湍流模型，采用多重参考系模型求解稳态下的搅拌流场．根据模拟结果及相关数据得出，穿流型搅拌器与普通搅拌器比较，可在更低的功耗下获得更大的速度梯度和更明显的涡流效应，有效强化搅拌；开孔位置在远端的穿流型搅拌器在相同转速下扭矩最小，功耗最低；开孔位置离搅拌轴越远，功耗下降越明显，且在一定转速范围内，搅拌转速越高，效果越明显．

Numerical simulation of hole position of punched impeller

To further reduce energy consumption and explore the hole position effect on the mixing of punched impeller, numerical simulation was taken with eight kinds of different hole position punched impellers about mixing flow field and power characteristics under the same hole size and opening rate in the liquid-liquid conditions tank. In simulation process, holes position were classified into three types of near end, middle end and distal end with holes uniform distribution on corresponding position ;the shaft, agitator and surrounding area were set to be the moving area and the residual area were static area by simplified treatment of model based on tetrahedral mesh of the model grid. The standard k-a turbulence model of numerical simulation method and moving reference frame were used to solve steady- state mixing flow field. It is found that, compared with normal impeller, punched impeller reaches greater velocity gradient, more obvious eddy current and strengthen stirring of tank. The lowest power consumption is reached by choosing the punched impeller of distal type . The obvious effect of power consumption is reached by increasing the distance of hole and axis, meanwhile, the higher of mixing speed, and the more obvious of the effect at certain speed range.