Definition
A turbine in which the rotor is driven by the kinetic energy of a high-velocity jet of fluid or gas striking the blades. The pressure of the working fluid drops across the stationary nozzles before reaching the rotor, so the rotor blades extract energy from the speed of the flow rather than from any further pressure drop across them.
Plain English
A turbine wheel spun by the force of a fast-moving jet hitting its blades, like a paddle wheel being pushed by a strong stream of water.
Context Anchor
Seen in turbine engine theory, especially when comparing impulse and reaction turbine blade designs.
Derivation
Impulse comes from the Latin impulsus, meaning a push or strike. The name describes how the wheel turns: it is pushed by the impact of the jet, not by pressure expanding through the blades.
Why Pilots Care
Knowing the difference between impulse and reaction turbine stages helps a pilot understand how energy is extracted from hot gases in a turbine engine, which matters when reading about engine design, performance, and failure modes.
Analogy
Think of a garden hose aimed at a pinwheel. The water speeds up through the nozzle, then strikes the pinwheel blades and pushes them around. The pinwheel is an impulse wheel.
Grounding Statement
Picture hot gas being aimed through fixed openings into high-speed jets, then striking a wheel and making it spin.
Intuition Check
“Impulse” does not mean a brief electrical signal or a sudden urge here. It means the turbine is driven mainly by the push from high-speed gas hitting the moving blades.
Example Sentence 1
The first stage of the turbine is an impulse turbine, so the gas accelerates through the nozzles and strikes the blades at high velocity.
Example Sentence 2
Technicians inspected the impulse turbine blades for erosion after the engine experienced repeated high-power operations.