Influence of Variable Turbine Geometry on Engine Installation Losses and Cycle Selection
Final technical rept. Apr 1971-Nov 1972
PRATT AND WHITNEY AIRCRAFT GROUP EAST HARTFORD CT
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The trend in military aircraft is toward increasing thrust loading for improved maneuverability coupled with a requirement for extended subsonic cruise range at low power settings. Conventional turbine engines designed to meet these requirements must operate over large ranges of airflow between maximum power and cruise. As a result, the inlets and nozzles designed for these engines cannot perform efficiently with the low airflow rates typical of subsonic cruise operation. Variable turbine geometry, however, offers a promising approach for obtaining both high thrust loading and efficient cruise performance by permitting large amounts of thrust modulation at constant airflow rates. As an example, the performance of a turbojet engine, which provides efficient high-thrust maneuvering and supersonic operation, can be improved by variable turbine geometry to the point where it is competitive with a fixed- turbine-geometry turbofan engine in the low-thrust subsonic cruise regime.
- Jet and Gas Turbine Engines