Question:-
In reaction turbines, the draft tube is used
Option (A)
For the safety of the turbine
Option (B)
TO convert the Kinetic energy of flow by a gradual expansion of the flow cross-section
Option(C)
To destroy the undesirable eddies
Option(D)
For none of the above purpose
Correct Option:
(B)
Question Solution:
The draft tube has two purposes as follows :
(i) It permits a negative or suction head to be established at the runner exit thus making it possible to install the turbine above the tail race level without loss of head
(ii) It converts a large proportion of velocity energy rejected from the runner into useful pressure energy. i.e. acts as a recuperator of pressure energy
question-answer-faq-5910