This disclosure relates to gas turbine engines, and more particularly to fan blades for use in gas turbine engines.
A gas turbine engine, such as a turbofan engine for an aircraft, includes a fan section, a compression section, a combustion section and a turbine section. An axis of the engine is centrally disposed within the engine and extends longitudinally through the sections. The primary flow path for working medium gases extends axially through the sections of the engine. A secondary flow path for working medium gases extends parallel to and radially outward of the primary flow path.
The fan section includes a rotor assembly and a stator assembly. The rotor assembly of the fan includes a rotor disc and plurality of radially extending fan blades. The fan blades extend through the flow path and interact with the working medium gases and transfer energy between the fan blades and working medium gases. The stator assembly includes a fan case, which circumscribes the rotor assembly in close proximity to the tips of the fan blades.
During operation, the fan draws the working medium gases, more particularly air, into the engine. The fan raises the pressure of the air drawn along the secondary flow path, thus producing useful thrust. The air drawn along the primary flow path into the compressor section is compressed. The compressed air is channeled to the combustion section where fuel is added to the compressed air and the air/fuel mixture is burned. The products of combustion are discharged to the turbine section. The turbine section extracts work from these products to power the fan and compressed air. Any energy from the products of combustion not needed to drive the fan and compressor contributes to useful thrust.
Typical fan blades on gas turbine engines are made up of two design features, the airfoil and the root. The airfoil does all of the aero-mechanical work to produce thrust and compression. The root is contains the necessary attachment features to hold the airfoil in place. Some roots use either a pin or dovetail construction to attach to the rotor. The airfoil may be a highly contoured surface with complex splines that end at the root. In metallic structures it is easier to manufacture these transition shapes, but in composites these contours may lead to misaligned fibers, and ply drops which are poor for strength and durability.
Accordingly it is desirable to provide an improved fan blade with a composite airfoil.