Centrifugal pump similarity: discharge vs. rotational speed How does the discharge Q of a centrifugal pump vary with impeller rotational speed N (all else equal)? Choose the correct relation.
Mechanical Engineering
Hydraulic Machines
Difficulty: Easy
Choose an option
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AQ ∝ N
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BQ ∝ 1/N
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CQ ∝ N²
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DQ ∝ 1/N²
Answer
Correct Answer: Q ∝ N
Explanation
Concept For a given geometry and diameter, the flow (via Vf) scales with tip speed ∝ N, so Q ∝ area × Vf ∝ N.
Affinity law With constant diameter: Q ∝ N; Head H ∝ N²; Power P ∝ N³.
Final AnswerQ ∝ N