Optimized Turboprop Propylsion System Thrust and Fuel Burn by Integrated Design

The benefits of integrating the propulsion system design to take advantage of the flow field shed by one aircraft component on another was demonstrated during the recent development of two Garrett-powered high performance turboprop aircraft. Equivalent shaft horsepower (ESHP) increased approximately 11 percent and equivalent specific fuel consumption (ESFC) improved approximately five percent when components upstream of the engine were modified to enhance ram recovery and to supercharge the engine. The effect of supercharging resulted in a “ram recovery” greater than 1.0 at the cruise design point.

The improvements were obtained by modifying the following propulsion system components:

• An area-ruled spinner replaced the standard spinner to improve ram recovery.
• Aerodynamic cuffs were put on the propeller shank/spinner junction to improve ram recovery and to supercharge the engine. This also significantly improved propeller performance.
• The aircraft inlet was modified to accept the increased airflow swirl angle shed by the propeller cuffs.