In the Francis turbine, the runner blades are radial at the entrance and the discharge is radial at the outlet. For this turbine,
- Athe relative velocity is radial at the outlet
- Bthe absolute velocity is radial at the outletCorrect
- Cthe guide vane angle is 90°
- Dthe velocity of flow is constant
Solution
Concept
Radial discharge
Step-by-step solution
1. With radial discharge the whirl velocity at outlet is zero. 2. The absolute velocity is therefore radial.
Explanation
Vw2 = 0 means V2 is radial.
Why the other options are wrong
The relative velocity is not radial.
Shortcut
Radial discharge → V2 radial.
Correct answer: B) the absolute velocity is radial at the outlet