The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called

Concept:

Degree of reaction 

• Degree of reaction or reaction ratio (R) is defined as the ratio of the static pressure drop/increase in the rotor (moving blade) to the static pressure drop/increase in the stage (both fixed blade and moving blade) or as the ratio of static enthalpy drop in the rotor to the static enthalpy drop in the stage.
• \(Degree\;of\;reaction = \frac{{Enthalpy\;drop\;in\;Rotor}}{{Enthalpy\;drop\;in\;Stage}}\)
• Degree of reaction may also be defined as the ratio of enthalpy drop in the rotor to the enthalpy drop in a stage.
•  i.e. \({\rm{R}} = \frac{{{\rm{Static\;enthalpy\;drop\;or\;rise\;in\;rotor}}}}{{{\rm{Stagnation~enthalpy\;drop\;or\;rise\;in\;stage}}}}\)
• Or, \(R = \frac{{static\;pressure\;drop\;or\;rise\;in\;rotor}}{{stagnation\;pressure\;drop\;or\;rise\;in\;stage}}\)
• 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.
• And for Parson’s turbine or 50% reaction turbine R = 0.5 and for Hero’s turbine R = 1.