自動攪拌一體機設(shè)備在一定功率及槳葉情勢情況下,槳葉排液量以及壓頭可能通過轉(zhuǎn)變槳葉的直徑跟轉(zhuǎn)速的匹配來調(diào)節(jié),即大直徑槳葉配以低轉(zhuǎn)速的攪拌設(shè)備產(chǎn)生較高的流動作用跟較低的壓頭,而小直徑槳葉配以高轉(zhuǎn)速則產(chǎn)生較高的壓頭跟較低的流動作用。在攪拌槽中,要使微團彼此碰撞,的辦法是供給足夠的剪切速率。
Under the condition of certain power and blade situation, the discharge volume and pressure head of the blade of the automatic mixing all-in-one machine may be adjusted by changing the matching between the diameter of the blade and the rotating speed, that is, the mixing equipment with low rotating speed for large-diameter blade will produce higher flow effect and lower pressure head, while the mixing equipment with high rotating speed for small-diameter blade will produce higher pressure head and lower flow effect. In the stirred tank, the best way to make the pellets collide with each other is to supply sufficient shear rate.
從自動攪拌一體機來看,恰是因為流體速度差的存在,才使流體各層之間彼此混淆,因此,凡攪拌進程老是波及到流體剪切速率。剪切應(yīng)力是一種力,是攪拌利用中氣泡疏散跟液滴破碎等的真 正起因。
From the perspective of the automatic mixing machine, it is precisely because of the existence of fluid velocity difference that the fluid layers are confused with each other. Therefore, the mixing process always affects the fluid shear rate. Shear stress is a kind of stress, which is the real cause of bubble evacuation and droplet breakage in stirring.
就槳葉區(qū)而言,無論何種漿型,當(dāng)槳葉直徑一定時,大剪切速率跟均勻剪切速率都隨轉(zhuǎn)速的進步而增加。但當(dāng)轉(zhuǎn)速一定時,大剪切速率跟均勻剪切速率與槳葉直徑的關(guān)聯(lián)與漿型有關(guān)。當(dāng)轉(zhuǎn)速一定時,徑向型槳葉大剪切速率隨槳葉直徑的增加而增加,而均勻剪切速率與槳葉直徑大小無關(guān)。
For the blade area, no matter what type of propeller, when the blade diameter is constant, the large shear rate and uniform shear rate increase with the progress of rotating speed. However, when the rotating speed is constant, the correlation between large shear rate and uniform shear rate and blade diameter is related to the pulp type. When the rotating speed is constant, the large shear rate of radial blade increases with the increase of blade diameter, while the uniform shear rate is independent of blade diameter.
這些有關(guān)槳葉區(qū)剪切速率的概念,在攪拌設(shè)備縮小及放大設(shè)計中須要特別小心。因小槽與大槽比較,小槽攪拌設(shè)備往往存在高轉(zhuǎn)速、小槳葉直徑及低葉尖速度等特點,而大槽攪拌設(shè)備往往存在低轉(zhuǎn)速大槳葉直徑及高葉尖速度等特點。
These concepts about the shear rate in the blade area need special care in the reduction and amplification design of mixing equipment. Due to the comparison between small tank and large tank, small tank mixing equipment often has the characteristics of high speed, small blade diameter and low blade tip speed, while large tank mixing equipment often has the characteristics of low speed, large blade diameter and high blade tip speed.