直斜错位桨搅拌槽内流场的探究

Flow field in stirred tankof straight-gradient dislocated agitator

为了进一步增强直斜错位搅拌桨的搅拌效果.对桨叶直径D=160 mm,不同桨叶间距的搅拌桨进行三维数值模拟,通过分析它们的宏观流场特征,综合速度、轴向速度、径向速度、切向速度的变化规律及死区分布规律,探究直斜错位桨的最优桨叶间距.结果表明:当桨叶间距在3D/4-3D/4范围内,各速度分布的不均匀性较小,搅拌槽中基本无死区且流体的循环范围最广.当桨叶间距在D/2-D范围内,高速区范围最大,且无明显变化.当桨叶间距在3D/4-D范围内,流体的平均速率较大,当桨叶间距为3D/4时,轴向速度和径向速度较大,故搅拌效果较佳,混合效率较高.因此,桨叶间距在3D/4-7D/8范围内可取最佳值.

To improve thestirringperformance, the fluid flow in stirred tank withdifferent agitators was numerically simulated by FLUENT as agitators diameter is 600 mm. The optimal span of the agitator was explored by analyzingthe characteristic of flow field, the distribution of velocity, axial velocity,radial velocity, tangential velocity and dead-zone volume. The researchindicates that the larger area of fluid circulation and the more uniformvelocity distribution appear in stirred tank, and dead-zone largely disappears whenthe span of blades is between 3D/4 and 7D/8; the large-scale regional speedy fluid is observed and itdoes not change obviously when the span is between D/2 and D; the fluid moves with the larger average velocity in stirredtank when the span is between 3D/4 and D;the better mixtureperformance and higher stirred efficiency can be obtained due to the largeraxial velocity and radial velocity when the span is 3D/4. Therefore, the optimal span of blades can be obtained in thescope of 3D/4 to 7D/8.