Flow behavior index

MWCNT Multiwall carbon nanotubes n Flow behavior index... 

T able 3 Shear viscosity, die swell, flow behavior index, and consistency index of various samples at a shear rate of 61.2 s-1... 

Sample designation Shear viscosity (kPa-s) Die swell (%) Flow behavior index (n) Consistency index (k) (xIO 4 kPa-s)... 

The flow-behavior index n (or n ), which characterizes the extent of the deviation of a fluid from Newtonian behavior. 

The consistency index K (or K ), which characterizes the consistency or thickness of a fluid. It is analogous to the viscosity of a Newtonian fluid and similarly enables quantitative comparison of the consistency of fluids having identical flow-behavior indexes. 

As pointed out in Section I, viscosities are really meaningful if compared only for Newtonian fluids or at specified shear rates for other materials. A similar limitation must be imposed on the consistency indexes K and K values of either are comparable only for fluids with the same flow behavior indexes n or n . 

Fig. 8. Dependence of velocity profiles upon flow-behavior index. Average velocity of 5 ft./sec. in all cases.

The flow-behavior index n (or n) may be assumed independent of temperature and concentration for small changes in such conditions (R3). For larger changes, Vaughn (V2) has found the following generalizations to be valid for water-dispersible polymers ... 

For Bingham plastics the changes in yield value t with temperature have been reported generally to resemble changes of the flow-behavior index n similarly, the coefficient of rigidity ri frequently changes as rapidly with temperature as the viscosity of the suspending medium (Gl). 

Decreases in concentration or increases in temperature usually decrease the consistency indexes K and K but leave the flow-behavior indexes n and n relatively unaltered. The latter appear to be determined primarily by the components of the non-Newtonian fluid and increase only slightly with increases in temperatures or decreases in concentration for pseudoplastic materials. 

Fig. 9. Dependence of kinetic-energy correction factor upon flow-behavior index.

Ward and DallaValle (W2) studied the two-phase cocurrent flow of air and four non-Newtonian fluids in three horizontal pipes (I.D. 0.82 to 1.60 in.). Flow rates were such that both phases were in turbulent motion. The flow-behavior index of the liquids used was varied from 0.31 to 1.00,... 

All the heat transfer data were for cooling of the polymeric solutions. The solutions were dilute, with apparent viscosities of the order of 1 to 15 cp., but nevertheless the deviation from Newtonian behavior was very significant. The flow-behavior index n varied from 0.65 to 1.00. 

With these instruments the relationship between DAP/4L and 8 V/D is obtained directly. On a logarithmic plot of DAP/4L versus 8 V/D the slope of the curve at any point is equal to the flow-behavior index n extension of the tangent to the curve at this point to a value of 8V/D of unity gives the corresponding value of the consistency index K. ... 

L Length of a pipe or tube, ft. n Flow behavior index, defined by Eq. (3), dimensionless n Flow behavior index defined by Eq. (19), dimensionless... 

Determine the values of the consistency index K, the flow behavior index n, and also the apparent viscosity at the shear rate of 50 s . ... 

The values of the consistency index K and the flow behavior index n of a dilatant fluid are 0.415 and 1.23, respectively. Estimate the value of the apparent viscosity of this fluid at a shear rate of 60 s T... 

Estimate the stirrer power requirement P for a tank fermentor, 1.8 m in diameter, containing a viscous non-Newtonian broth, of which the consistency index A = 124, flow behavior index n = 0.537, density p = 1050 kg m", stirred by a pitched-blade, turbine-type impeller of diameter d = 0.6 m, with a rotational speed AT of 1 s . ... 

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