Swept fan blade
AssigneeROLLS-ROYCE plc
InventorPaul A. Rowlands
Life of this patent
Estimating the term…
Abstract
A swept fan blade design for the low pressure compressor rotor or fan rotor stage of a ducted fan gas turbine engine has a leading edge swept forward near the hub up to a first radial height, then rearward up to second radial height and finally is swept forward again up to the blade tip. The aerodynamic effect is to produce a mid-height bias to the airflow enabling the tip region to be given increased twist and to possess increased resistance to foreign object damage. The design also provides a rear radial blade stacking axis to help reduce internal stresses due to centrifugal forces.
Claims13
A fan stage of a ducted fan gas turbine engine, comprising
- a fan casing having an inner duct wall which in a fan rotor region is convergent in the downstream direction;
- and
- a fan rotor including a multiplicity of swept fan blades spaced apart around a hub mounted concentrically with respect to the fan duct, each of said swept fan blades having a tip profile which in revolution is convergent so as to substantially correspond to the convergent duct wall, a leading edge of variable sweep angle which varies with increasing blade height or distance from the axis of rotation, said sweep angle having a forward sweep angle in a first height region between the root and a first intermediate radius, a rearward sweep angle in an intermediate height region between the first intermediate radius and a second intermediate radius, a forward sweep angle in a third height region between the second intermediate radius and the tip of the blade, a stagger angle which increases progressively with blade height.
A fan stage of a ducted fan gas turbine engine that is at least in part rotatable about an axis of rotation and defines a downstream direction along the axis of rotation, comprising:
- a fan casing that defines an inner duct wall having a fan rotor region, the inner duct wall of the fan casing at the fan rotor region being convergent;
- a hub disposed concentrically relative to the fan casing;
- a fan rotor that includes multiple swept fan blades, the swept fan blades being spaced apart around the hub, each of the multiple swept fan blades having:
- a tip profile that is convergent so as to substantially correspond to the convergent inner duct wall of the fan casing;
- a leading edge that defines a variable sweep angle in a direction perpendicular to the axis of rotation, the leading edge including:
- an inner region adjacent the hub, the inner region defining a forward sweep angle;
- an intermediate region between the inner region and the fan casing, the intermediate region defining a rearward sweep angle;
- and
- an outer region between the intermediate region and the fan casing, the outer region defining a forward sweep angle.
Dependencies are inferred from the claim text.