9.5 Bulb and Tube Turbines
339
and blade positions corresponding with turbine operation in both senses. In periods
of small difference in level, it may be profitable to pump in the sense as during the
previous turbine phase. This operation allows an increase of available energy for
the following turbine phase. Both turbine and pump functions can be performed by
the same bulb machine. Leaving the stator vanes in their original position, turning
Fig. 9.19 Bulb turbine with low head
Fig. 9.20 Velocity triangles for turbine operation in normal sense (a), and reverse sense (b), and
for pump operation in normal sense (c), and reverse sense (d)