Francis turbine: Definition of speed ratio. Speed ratio is defined relative to the runner peripheral (rim) speed at inlet and the ideal jet/stream velocity √(2gH). State whether the given definition is correct. Choose the correct option.

Difficulty: Easy

Correct — speed ratio = theoretical jet velocity / peripheral speed
Incorrect — speed ratio = peripheral speed / theoretical jet velocity (u / √(2gH))
Depends on specific speed; no fixed definition
Valid only for Pelton wheels, not Francis turbines

Correct Answer: Incorrect — speed ratio = peripheral speed / theoretical jet velocity (u / √(2gH))

Explanation:

Definition

For reaction turbines (e.g., Francis), speed ratio φ = u / √(2 g H), where u is runner peripheral speed and √(2 g H) is the ideal velocity head equivalent.

Reasoning
The statement reverses numerator and denominator. The correct ratio places runner speed in the numerator.

Final Answer
Incorrect — speed ratio = u / √(2gH)

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