Which blade type is described as combining impulse and reaction characteristics?

Which blade type is described as combining impulse and reaction characteristics?

• A. Impulse
• B. Reaction
• C. Impulse-reaction
• D. Mixed

Answer: (C)

In turbine blades, energy transfer can come from changing the flow’s momentum (impulse) or from a pressure drop along the blade (reaction). A blade that combines both effects uses a nozzle-like action to impart velocity (impulse) while also developing a pressure gradient along the blade surface (reaction). This dual mechanism is described as impulse-reaction. It captures the idea that energy is extracted through both accelerating the fluid and a continuous pressure drop on the blade, giving a balanced performance across operating conditions. Pure impulse blades rely mainly on velocity change with little blade pressure drop, and pure reaction blades rely mainly on pressure changes along the blade with less external velocity imparted.

In turbine blades, energy transfer can come from changing the flow’s momentum (impulse) or from a pressure drop along the blade (reaction). A blade that combines both effects uses a nozzle-like action to impart velocity (impulse) while also developing a pressure gradient along the blade surface (reaction). This dual mechanism is described as impulse-reaction. It captures the idea that energy is extracted through both accelerating the fluid and a continuous pressure drop on the blade, giving a balanced performance across operating conditions. Pure impulse blades rely mainly on velocity change with little blade pressure drop, and pure reaction blades rely mainly on pressure changes along the blade with less external velocity imparted.