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Viscosity concept and unit conversion

Date:2012年11月29日 11:24

Transport all kinds of fluid has a certain viscosity, namely fluid between all the parts have relative motion appear, doing all the parts of the relative motion between fluid, can produce stop the relative motion of the inner friction. The inside of the size of the friction force and the viscosity of the conveying medium is proportional.
According to Newton's internal friction law: T = UdV/dn, including: dv/dn for velocity gradient,
A. U for dynamic viscosity, the unit is Pa s. (N/m2 s.), dynamic viscosity of the international unit for centipoise (CP),
The relationship between the for: 1 pa s. = 10 p (ground) = 1000 cp (CPS)
1 centipoise (1 cp) = 1 milli PASCAL. Seconds (1 mpa s.)
100 centipoise (100 cp) = 1 berth (1 p)
1000 milli PASCAL. Seconds (1 mpa. S) = 1 PASCAL. Seconds (1 pa s.)
B. kinematic viscosity V: namely dynamic viscosity u and density ρ ratio: V = u/ρ, kinematic viscosity unit for m2 / s, habit, the unit is: CST (the best callus induction/s)
U - dynamic viscosity (mPa s.)
ν - kinematic viscosity (the best callus induction/s)
ρ - and measurement of kinematic viscosity the same temperature sample density (g/cm3)
The relationship between the for: 1 m2 / s = 10000 st (si) = 1000000 CST (CST)
1 st (si) = 10-4 m2 / s
1 CST (CST) = 10-6 m2 / s
C. engler viscosity E: it belongs to relative viscosity, it is 200 cm3 measured medium fluid in a certain temperature, from engler viscometer outflow required time t, with volume in distilled water and c for time t. (51 s), i.e., the ratio of the E = t/t.
D. engler viscosity E and kinematic viscosity, the conversion relations between V: V = (7.31 e-6. 31 / E) / 1000000 (m2 / s)
Viscosity and temperature, pressure relationship: μ = μ. Ebp (t/t) k
μ - gauge pressure for P, temperature of t of dynamic viscosity
μ.- in an atmospheric pressure, temperature of t. The dynamic viscosity
B, k - depending on the kind of liquid and decide constant, the oil: k = 2, b = 0.014 0.03
The c, d items are seldom used.
General product dynamic viscosity:
Water 1 centipoise (cP),
Beer 3 cP
SAE 30 motor oil 200 cP
Ketchup 50000 cP
Mineral oil 64000 cP
Toothpaste 190000 cP
Peanut butter 250000 cP

 

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