Jump to navigation Jump to search Not to be confused with propfan. A turboprop engine is a turbine engine that drives an russian single engine turboprop propeller.

In its simplest form a turboprop consists of an intake, compressor, combustor, turbine, and a propelling nozzle. Air is drawn into the intake and compressed by the compressor. In contrast to a turbojet, the engine’s exhaust gases do not generally contain enough energy to create significant thrust, since almost all of the engine’s power is used to drive the propeller. Owing to the additional expansion in the turbine system, the residual energy in the exhaust jet is low. Turboprops can have bypass ratios up to 50-100 although the propulsion airflow is less clearly defined for propellers than for fans. Unlike the small diameter fans used in turbofan jet engines, the propeller has a large diameter that lets it accelerate a large volume of air. This permits a lower airstream velocity for a given amount of thrust.

Propellers lose efficiency as aircraft speed increases, so turboprops are normally not used on high-speed aircraft above Mach 0. While most modern turbojet and turbofan engines use axial-flow compressors, turboprop engines usually contain at least one stage of centrifugal compression. While the power turbine may be integral with the gas generator section, many turboprops today feature a free power turbine on a separate coaxial shaft. This enables the propeller to rotate freely, independent of compressor speed. Alan Arnold Griffith had published a paper on turbine design in 1926.