Concrete mixer is determined by many parameters, so it is impossible to describe a concrete mixer with any single parameter. Shaft power (P), blade discharge (q), head (H), blade diameter (d) and mixing speed (n) are five basic parameters to describe a concrete mixer. The discharge 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）的混凝土搅拌车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，办法是提供足够的剪切速率。
Under the condition of a certain power and blade type, the discharge capacity (q) and the pressure head (H) of the blade can be adjusted by changing the matching of the blade diameter (d) and the rotation speed (n), that is, the large-diameter blade with a low rotation speed (to ensure the same shaft power) of the concrete mixer produces a higher flow effect and a lower pressure head, Small diameter blades with high speed produce higher head and lower flow effect. In the stirred tank, the way to make the micro clusters collide with each other is to provide enough shear rate.
从混凝土搅拌车理看，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原因。需要指出的是，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 theory of concrete mixer, it is the existence of fluid velocity difference that makes the fluid layers mix with each other. Therefore, the shear rate of fluid is always involved in the mixing process. Shear stress is a kind of stress, which is the cause of bubble dispersion and droplet breakage in stirring applications. It should be pointed out that the shear rate of each point in the whole stirred tank is not consistent.
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：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。
The study of shear rate distribution shows that there are at least four kinds of shear rate values in a stirred tank. They are: in terms of blade area, no matter what type of slurry, when the blade diameter is fixed, the shear rate and average shear rate increase with the increase of rotating speed.
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。这些有关桨叶区剪切速率的概念，在混凝土搅拌车缩小及放大设计中需要特别当心。因小槽与大槽相比，小槽混凝土搅拌车往往具有高转速（N）、小桨叶直径（D）及低叶尖速度（ND）等特性，而大槽混凝土搅拌车往往具有低转速（N)大桨叶直径（D）及高叶尖速度（ND）等特性。
However, when the rotational speed is constant, the relationship between the shear rate, average shear rate and blade diameter is related to the shape of the blade. When the rotating speed is constant, the shear rate of radial blade increases with the increase of blade diameter, while the average shear rate is independent of blade diameter. These concepts of shear rate in blade area need special attention in the design of concrete mixer truck. Compared with large tank, small tank concrete mixer often has the characteristics of high speed (n), small blade diameter (d) and low tip speed (nd), while large tank concrete mixer often has the characteristics of low speed (n), large blade diameter (d) and high tip speed (nd).
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