Centrifugal pump similarity: discharge vs. impeller diameter For a given speed and inlet width, how does discharge Q vary with impeller diameter D in a centrifugal pump? Choose the correct dependence.
Mechanical Engineering
Hydraulic Machines
Difficulty: Easy
Choose an option
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ADirectly proportional to D
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BInversely proportional to D
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CDirectly proportional to D²
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DInversely proportional to D²
Answer
Correct Answer: Directly proportional to D
Explanation
Concept At inlet, Q = π D b Vf. For fixed b and similar Vf (same N), Q scales with D.
Notes Under full similarity (b ∝ D and Vf ∝ D N), Q would scale as D³ N, but with b and N fixed as in many textbook MCQs, the direct proportionality to D is appropriate.
Final AnswerDirectly proportional to D