Definition
A turbine in which the rotor blades are shaped like airfoils so that the working fluid (steam, gas, or hot exhaust) accelerates as it passes between them. The pressure drop across each blade row produces a reactive force that turns the rotor, similar to the thrust produced when air accelerates over a wing.
Plain English
A spinning wheel powered by gas or steam, where the blades themselves are shaped to speed the gas up as it passes through. The push back from that speeding-up gas is what turns the wheel.
Context Anchor
Seen in turbine-engine theory and maintenance discussions when explaining how energy from hot gas is changed into turning force.
Derivation
From Newton's third law: every action has an equal and opposite reaction. The blades 'react' to the accelerating gas by being pushed in the opposite direction.
Why Pilots Care
Most modern turbojet and turbofan engines use turbine sections that combine impulse and reaction designs. Knowing the difference helps a pilot understand how the engine converts hot, high-pressure exhaust into the rotational energy that drives the compressor and fan.
Analogy
A loose garden hose can whip around when water shoots out of it. The water goes one way, and the hose is pushed the other way. A reaction turbine uses that same push-back idea in a controlled way with shaped blades.
Intuition Check
Reaction does not mean the turbine is simply responding quickly. Here, it means the turbine turns because flowing gas or liquid creates an equal push back on the moving blades.
Example Sentence 1
The low-pressure turbine in this engine uses reaction turbine blades, so the hot gases speed up as they pass through and push the rotor around.
Example Sentence 2
During overhaul the technician checked the reaction turbine blades for cracks and erosion.