Rotor losses clearance loss

The adiabatic head that is actually available at the rotor discharge is equal to the theoretical head minus the head losses from the shock in the rotor, the incidence loss, the blade loadings and profile losses, the clearance between the rotor and the shroud, and the secondary losses encountered in the flow passage... 

Clearance loss. This loss is caused by flow passing between the stationary shroud and the rotor blades and is a function of the blade height and clearance. The clearance is usually fixed by tolerances and, for smaller blade heights, the loss is usually a greater percentage. This loss varies between 1 and 2%. 

The turbine assembly has many losses that combine to produce significant frictional work through frictional torques exerted by the casing. These include the fluid scrubbing on the back of the disk and on the back of the rotating shroud, if used, stator biade fluid frictional losses, and rotor blade frictional losses. Other losses include leakage from clearances between the rotor... 

Due to the excessive vibrations of the rotors, parts of the labyrinth seals had to be removed by machining, thus increasing their clearances. This resulted in the additional sealing and cooling gas losses amounting to 5.3 MW. 

Because of the large flow velocities which are required (10-100 m/s) hydraulic friction losses as well as losses due to internal leakage through the rotor clearances are high. The total efficiency of centrifugal pumps depends on the specific speed rtq (Figure 9.8) [11, 12]. 

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