clearance wear ring on pump performance

[mceko]

Dear All,
I'm looking for the formula to find losses in wear ring, so I can find the relation between wear ring clearance and pump performance. I want to proove it. Anyone knows about this? I really need it.

Thank's
mceko

 

[abeltio]

try stepanoff's: design of centrifugal and axial pumps.
cheers.
a.

 

[vanstoja]

Impeller wear ring clearance versus pump efficiency can be determined from Section 2.1 of the Pump Handbook (1976 Edition)using Fig.56 (wear ring clearance vs joint diameter), the equation for volumetric efficiency on page 2-17, and Eq. 19 for overall pump efficiency. The leakage flowrate Q_L to front and back shrouds can be calculated as velocity times seal annulus area using, for velocity, SQRT 2gH where H is design flowrate head along with an appropriate geometrical flow resistance factor for the seal gaps which usually includes entrance and exit loss factors of 1.0+0.5=1.5 velocity heads. A plain annular orifice coefficient may be near 0.6. If labyrinth seals are employed in the seal gaps, then experimental data is needed for resistance coefficients of single labyrinth teeth geometries which is multiplied by the number of teeth minus 1.0. Resistance coefficients for a number of geometries of seal gaps are provided in Stepanoff (1957).