Mixer is determined by many parameters. It is impossible to describe a mixer with any single parameter. Shaft power (P), blade discharge (q), head (H), blade diameter (d) and mixing speed (n) are the five basic parameters to describe a mixer. The discharge volume of the blade is directly proportional to the flow standard of the blade itself, the first power of the blade speed and the third power of the blade diameter. The shaft power consumed by stirring is directly proportional to the specific gravity of the fluid, the power criterion of the blade itself, the third power of the rotating speed and the fifth power of the blade diameter.

在一定功率及桨叶形式情况下，桨叶排液量（Q）以及压头（H）可以通过改变桨叶的直径（D）和转速（N）的匹配来调节，即大直径桨叶配以低转速（保证轴功率不变）的搅拌机产生较高的流动作用和较低的压头，而小直径桨叶配以高转速则产生较高的压头和较低的流动作用。在搅拌槽中，要使微团相互碰撞，的办法是提供足够的剪切速率。

Under certain power and blade form, the discharge capacity (q) and head (H) can be adjusted by changing the matching of diameter (d) and rotating speed (n), that is, the mixer with large diameter blades and low speed (ensuring the same shaft power) produces higher flow effect and lower head, while small diameter blades with high speed produce higher head and lower head Mobility. In a stirred tank, the only way to make the pellets collide with each other is to provide sufficient shear rate.

从搅拌机理看，正是由于流体速度差的存在，才使流体各层之间相互混合，因此，凡搅拌过程总是涉及到流体剪切速率。剪切应力是一种力，是搅拌应用中气泡分散和液滴破碎等的真正原因。必须指出的是，整个搅拌槽中流体各点剪切速率的大小并不是一致的。

From the view of stirring mechanism, it is because of the existence of fluid velocity difference that the fluid layers are mixed with each other. Therefore, the shear rate of fluid is always involved in the mixing process. Shear stress is a kind of force, which is the real cause of bubble dispersion and droplet breakup in stirring applications. It must be pointed out that the shear rate of fluid in the whole stirred tank is not the same.

通过对剪切速率分布的研究表明，在一个搅拌槽中少存在四种剪切速率数值，它们是：实验研究表明，就桨叶区而言，无论何种浆型，当桨叶直径一定时，剪切速率和平均剪切速率都随转速的提高而增加。但当转速一定时，剪切速率和平均剪切速率与桨叶直径的关系与浆型有关。当转速一定时，径向型桨叶剪切速率随桨叶直径的增加而增加，而平均剪切速率与桨叶直径大小无关。

The results show that there are at least four kinds of shear rate values in a stirred tank. They are: the experimental results show that the maximum shear rate and the average shear rate increase with the increase of the rotating speed, regardless of the size of the impeller. However, when the rotating speed is constant, the relationship between the maximum shear rate and the average shear rate and the blade diameter is related to the pulp shape. When the rotating speed is constant, the maximum shear rate of radial blade increases with the increase of blade diameter, but the average shear rate has nothing to do with the blade diameter.

这些有关桨叶区剪切速率的概念，在搅拌机缩小及放大设计中需要特别当心。因小槽与大槽相比，小槽搅拌机往往具有高转速（N）、小桨叶直径（D）及低叶尖速度（ND）等特性，而大槽搅拌机往往具有低转速（N)大桨叶直径（D）及高叶尖速度（ND）等特性。

These concepts about the shear rate in the blade zone need to be taken care of in the design of the mixer to reduce and enlarge. Compared with the large tank, the small tank mixer often has the characteristics of high speed (n), small blade diameter (d) and low blade tip speed (nd), while the large tank mixer often has the characteristics of low speed (n), large blade diameter (d) and high blade tip speed (nd).
相关标签：中科自上料搅拌机