In an impulse reaction turbine stage, the heat drops in fixed and moving blades are 28.32 kJ/kg and 18.61 kJ/kg, respectively. The degree of reaction for the stage will be: 

Concept:

Degree of Reaction (R):

• The degree of reaction is the ratio of the enthalpy drop in the rotor to the enthalpy drop in a stage.
• In the case of an impulse turbine, there is no change in the enthalpy in the rotor, so the degree of reaction is zero (R = 0).
• For Parson's turbine or 50% reaction turbine R = 0.5 and for Hero's turbine R = 1.

\(R = \frac{\Delta h _{mb}}{\Delta h_{stage}} = \frac{\Delta h _{mb}}{\Delta h_{mb} + \Delta h_{fb} }\)

where, ∆h_mb = Enthalphy Drop across Moving Blade, ∆h_fb = Enthalphy Drop across Fixed Blade

Calculation:

Given:

 ∆hmb = 18.61 kJ/kg, ∆hfb = 28.32 kJ/kg

\(R = \frac{18.61}{18.61 + 28.32}\)

R = 0.396