Hydraulic Machines MCQ with answer and solution

Concept

Impeller blade shape for centrifugal pumps

Formula

NONE

Step-by-step solution

1. The shape of impeller blades affects the efficiency and pressure head developed by a centrifugal pump. 2. Backward curved blades generally offer higher efficiency and stable performance under varying loads. Answer: A

Explanation

Centrifugal pumps achieve maximum efficiency when equipped with backward-bent impeller blades because they provide smooth flow transitions and stable head-discharge performance. Backward curvature reduces turbulent energy losses compared to forward-curved or straight blades. Therefore, option A is correct.

Why the other options are wrong

B) Forward-bent blades lead to lower efficiency and pressure instability. C) Straight blades are less efficient than curved blades.

Shortcut

Centrifugal pumps achieve maximum efficiency and stable performance using backward-curved blades.

Common mistake

Selecting forward-curved blades assuming higher discharge velocity translates to higher overall efficiency.