Definition
A turbine in which exhaust gases enter the wheel from the outer rim and flow inward toward the center, turning the wheel as they pass through. Commonly used in turbochargers and small gas turbine engines because it produces high power for its size and is simple to manufacture.
Plain English
A spinning wheel driven by hot gas that enters around its edge and flows inward toward the middle. The inward rush of gas spins the wheel, which then drives a shaft.
Context Anchor
Seen in powerplant study when comparing turbine designs or describing how a turbine engine, auxiliary power unit, or turbocharger extracts power from hot gas.
Derivation
Radial means 'along a radius'—from the outer edge inward toward the center, like spokes on a wheel. Inflow means the gas flows in toward the center. So a radial-inflow turbine is one where the working gas flows inward along the radius. This is the opposite of an axial turbine, where gas flows along the shaft.
Why Pilots Care
It recovers energy from exhaust to increase manifold pressure, allowing higher power output at altitude in turbocharged piston aircraft.
Grounding Statement
Picture hot gas entering all around the outside of a small wheel and rushing inward toward the center as the wheel spins.
Intuition Check
Do not picture the gas moving straight from front to back through the turbine. In a radial-inflow turbine, the gas moves from the outside edge inward toward the center.
Example Sentence 1
The turbocharger on this engine uses a radial-inflow turbine driven by the exhaust gases.
Example Sentence 2
Technicians check the radial-inflow turbine blades for cracks or erosion during turbocharger overhaul.