In: Other
How to calculate an average viscosity. Give equation for it.
Suppose we have a mixture of two liquids where the kinematic viscosity of one liquid A is νa and that of another liquid B is vb, then the average kinematic viscosity of this mixture of liquids is given by the equation:
This equation was proposed by Gambill and is known as Gambill Method.
Another way of calculating the average viscosity of a mixture of
liquids is determined by using Refutas equation:
In this method the Viscosity Blending Number (VBN) of each
component is calculated using the following formula:
Where vi is the kinematic viscosity of component i.
After calculating this, the VBN of the mixture is calculated for
which we have to calculate the average viscosity:
where xi is the mass fraction of component i.
Using the value of VBN of mixture, we can determine the average
viscosity of that mixture using the following correlation:
If instead of mass fraction, volume fraction is given, then we use
the following formula to determine VBN of each component:
where vi is the kinematic viscosity of component i.
Then VBN of the mixture is given by:
where Vi is the volume fraction of component i.
Therefore the average viscosity of the mixture is given by:
Here exp stands for exponential constant and has the value of 2.718
These are the formulae/ correlation used to determine the average viscosity.