Question Bank • QB_IDE_EXP_045 NAT • 2 Marks

Section 5: Irrigation and Drainage Engineering

Wells and Pumps

Subtopic: Pump characteristics

Question Statement:

A centrifugal pump running at $1450\text{ rpm}$ delivers $0.05\text{ m}^3\text{/s}$ against a total head of $20.0\text{ m}$. If the pump speed is increased to $1740\text{ rpm}$, the new discharge in $\text{m}^3\text{/s}$ governed by affinity laws is ________ (answer in exact decimal).

Answer Key:

0.06

Step-by-Step Solution & Explanation

From pump affinity laws: $\frac{Q_2}{Q_1} = \frac{N_2}{N_1}$ Given: • $N_1 = 1450\text{ rpm}$ • $N_2 = 1740\text{ rpm}$ • $Q_1 = 0.05\text{ m}^3\text{/s}$ $Q_2 = Q_1 \times \frac{1740}{1450} = 0.05 \times 1.20 = 0.060\text{ m}^3\text{/s}$
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