Question

The degree of reaction in an axial compressor stage is

• A. The ratio of static pressure rise in the rotor to total stage enthalpy rise
• B. The ratio of rotor speed to airflow speed
• C. Always \(0.5\) in all compressors
• D. Ratio of inlet velocity to exit velocity

Hint:

The degree of reaction is \[ \boxed{ R = \frac{\Delta h_{\text{rotor}}} {\Delta h_{\text{stage}}}. } \] Typical axial compressor stages have \[ \boxed{ R\approx0.5, } \] but it is not always exactly \(0.5\).

Answer 1

The Correct Option is A

Step 1: Recall the definition of degree of reaction. The degree of reaction is defined as \[ \boxed{ R = \frac{\text{Static enthalpy rise in the rotor}} {\text{Total enthalpy rise of the stage}}. } \] Since the rotor static enthalpy rise is associated with the pressure rise produced in the rotor, \[ \boxed{ R = \frac{\text{Rotor static pressure rise}} {\text{Total stage enthalpy rise}}. } \]

Step 2: Identify the correct option. Therefore, \[ \boxed{\text{The ratio of static pressure rise in the rotor to total stage enthalpy rise}} \] is the correct answer. Thus, \[ \boxed{(A)} \] is the correct answer.