Hydraulic Machines MCQ with answer and solution

Concept

Turbines are classified based on the head of water available: Pelton (High Head), Francis (Medium Head), and Kaplan/Propeller (Low Head).

Step-by-step solution

1. Identify the type of turbine: Francis turbine is an inward mixed flow reaction turbine. 2. Recall the head classification: High head (> 250m) is for Pelton, Medium head (60m to 250m) is for Francis, and Low head (< 60m) is for Kaplan. 3. Match the turbine to the head: Francis turbine = Medium head.

Explanation

Francis turbine is a medium-head, medium-specific speed reaction turbine. It typically operates under heads ranging from 60 meters to 250 meters, though modern designs can extend this range slightly.

Why the other options are wrong

A: Low head is specifically for Kaplan or Propeller turbines. B: High head is specifically for Pelton wheel turbines. D: Turbines are designed for specific ranges of head and discharge to maintain efficiency; no single turbine is ideal for 'any' head.

Shortcut

Remember 'PFK' for Head: Pelton (High), Francis (Medium), Kaplan (Low).

Common mistake

Confusing Francis with Kaplan; remember that Kaplan requires the least head but the highest discharge.