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.
在一定功率及槳葉形式情況下，槳葉排液量（Q）以及壓頭（H）可以通過改變槳葉的直徑（D）和轉(zhuǎn)速（N）的匹配來調(diào)節(jié)，即大直徑槳葉配以低轉(zhuǎn)速（保證軸功率不變）的混凝土攪拌車產(chǎn)生較高的流動作用和較低的壓頭，而小直徑槳葉配以高轉(zhuǎn)速則產(chǎn)生較高的壓頭和較低的流動作用。在攪拌槽中，要使微團(tuán)相互碰撞，辦法是提供足夠的剪切速率。
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.
從混凝土攪拌車?yán)砜?，正是由于流體速度差的存在，才使流體各層之間相互混合，因此，凡攪拌過程總是涉及到流體剪切速率。剪切應(yīng)力是一種力，是攪拌應(yīng)用中氣泡分散和液滴破碎等的原因。需要指出的是，整個攪拌槽中流體各點(diǎn)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.
通過對剪切速率分布的研究表明，在一個攪拌槽中至少存在四種剪切速率數(shù)值，它們是：就槳葉區(qū)而言，無論何種漿型，當(dāng)槳葉直徑一定時(shí)，剪切速率和平均剪切速率都隨轉(zhuǎn)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.
但當(dāng)轉(zhuǎn)速一定時(shí)，剪切速率和平均剪切速率與槳葉直徑的關(guān)系與漿型有關(guān)。當(dāng)轉(zhuǎn)速一定時(shí)，徑向型槳葉剪切速率隨槳葉直徑的增加而增加，而平均剪切速率與槳葉直徑大小無關(guān)。這些有關(guān)槳葉區(qū)剪切速率的概念，在混凝土攪拌車縮小及放大設(shè)計(jì)中需要特別當(dāng)心。因小槽與大槽相比，小槽混凝土攪拌車往往具有高轉(zhuǎn)速（N）、小槳葉直徑（D）及低葉尖速度（ND）等特性，而大槽混凝土攪拌車往往具有低轉(zhuǎn)速（N)大槳葉直徑（D）及高葉尖速度（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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