Centrifugal losses includes bearing, shaft seal and the impeller rub against the disk losses.
First, the bearings, shaft seal friction loss
Pump shaft is supported on bearings within the pump in order to prevent leakage of liquid out, set the seal. When the pump shaft rotates at high speed on friction with the bearing and shaft seal. In general, frictional losses are small, as: △ N = (0.01 ~ 0.03) N
Where △ N– friction loss; N– prime mover transmitted to the pump shaft power.
Second, the impeller and disc friction loss
Centrifugal impeller rotating liquid-filled pump housing, then cover the outer surface of the impeller and the liquid occurs causing friction between the friction loss.
Disc friction loss throughout the mechanical loss accounted for a larger proportion, particularly in some of the low number of revolutions of the pump even more so. Relationship between disc friction loss and the ratio of the number of revolutions. Low specific speed pumps, discs
Friction loss stingy faster, such as specific speed ns = 30, the disc friction loss increases to 30% effective power; and high specific speed pumps, a smaller proportion of the disc friction loss. Multi-stage pumps in various percentage of energy loss in a typical case:
Shock and swirl loss is 7%
Impellers and disc of balance disc friction loss is 5%
Clearance leakage loss is 2%
Balance mechanism leakage is2%
Hydraulic surface friction loss is 4%