Question

The work done by the rotor in an axial compressor primarily results in

• A. Increase in air density only
• B. Increase in kinetic energy of the air, partly converted to pressure rise
• C. Heat loss to the surroundings
• D. Decrease in static pressure

Hint:

In an axial compressor, \[ \boxed{ \begin{aligned} \text{Rotor} &\rightarrow \text{Adds Energy (Velocity Increase)} \text{Stator} &\rightarrow \text{Diffuses Flow (Pressure Increase)} \end{aligned} } \]

Answer 1

The Correct Option is B

Step 1: Recall the function of the rotor. The rotor transfers mechanical energy from the shaft to the air. Initially, this energy appears mainly as an increase in the air's kinetic energy.

Step 2: Determine what happens in the compressor stage. The stator following the rotor acts as a diffuser. It converts a part of the kinetic energy into static pressure. Hence, \[ \boxed{ \text{Rotor} \Longrightarrow \text{Increase in kinetic energy} \Longrightarrow \text{Stator} \Longrightarrow \text{Pressure rise}. } \] Therefore, \[ \boxed{\text{Increase in kinetic energy of the air, partly converted to pressure rise}} \] is the correct answer. Thus, \[ \boxed{(B)} \] is the correct answer.