Question

For a given rotational speed of a rotor of an axial flow compressor, as the fan tip radius increases, the centrifugal stress on the fan blade

• A. Increases
• B. Decreases
• C. remains constant
• D. first increases and then decreases

Hint:

When designing rotors with larger radii, materials must be chosen carefully to withstand the higher centrifugal stresses.

Answer 1

The Correct Option is A

Step 1: Analyze the Centrifugal Stress.
Centrifugal stress in a rotating body, such as a compressor blade, is proportional to the square of the rotational speed and directly proportional to the radius of the rotation. Given a constant rotational speed, as the radius (fan tip radius) increases, the path of the blade tip travels faster, thus increasing the centrifugal force exerted.
Step 2: Conclusion.
Since the centrifugal force increases with an increase in radius, so does the stress on the blade due to this force.