Correlation of slip factor
editAccording to Stodola's equation if increase number of blade slip factor increase
or we choose a impeller consist infinite number of blade than slip factor get unity.
Stanitz's equation : The slip velocity is not function of the blade exit angle.
Balje's formula : for radial tip impeller or β2 = 90°
by above models slip factor is function of geometry and independent of flow rate.
Unified slip factor model : this model based on various models (Stodola's slip model
for radial impeller,Stanitz's,Baljes's,carter's rule for axial impeller).
in this model effect of the radial rotation,the turning of blade,the passage of width included.
conclusion
edit1.axial flow impeller have small value of slip factor because inlet and outlet
flow in same direction, so mostly used slip factor term in radial impeller and
mixed flow impeller.
2.if we increase number of blades guidance of fluid increase so slip factor
increase, maximum at particular value and further increment reduce slip factor
because increase blockage area.
3.slip factor not only function of geometry but also mass flow rate.
4.blade turning rate is negative or blade angle decrease toward the impeller
exit than slip factor increase with increasing flow rate and blade turning rate
is positive or blade angle increase toward the impeller exit than slip factor
increase with decrease flow rate.