초록 ▼

A boundary layer ingesting (BLI) blade having a span is provided and includes a root section connectable to a hub, a tip section disposable at a distance from the hub and having a pitch and a body extending in a spanwise dimension from the root section to the tip section. The root section has a loca

A boundary layer ingesting (BLI) blade having a span is provided and includes a root section connectable to a hub, a tip section disposable at a distance from the hub and having a pitch and a body extending in a spanwise dimension from the root section to the tip section. The root section has a local pitch from the root section to about a 70% span location, which is less than the pitch at the tip section, to thereby reduce local angles of attack in a boundary layer region defined in and around the root section.

대표청구항 ▼

1. A propeller including a hub and at least one boundary layer ingesting (BLI) blade having a span, the at least one BLI blade comprising: a root section having an inboard end connected to the hub and an outboard end, the inboard end of the root section having a chordal length and a maximum thicknes

1. A propeller including a hub and at least one boundary layer ingesting (BLI) blade having a span, the at least one BLI blade comprising: a root section having an inboard end connected to the hub and an outboard end, the inboard end of the root section having a chordal length and a maximum thickness location defined at approximately 25% of the chordal length;a tip section disposable at a distance from the hub and having a twist; anda body extending in a spanwise dimension from the outboard end of the root section to the tip section,the body having a local twist from the root section to about a 70% span location, which is greater than the twist of the tip section, to thereby reduce local angles of attack in a boundary layer region defined in and around the root section. 2. The propeller according to claim 1, wherein the inboard end of the root section has a chord length that is substantially greater than a thickness thereof and different from an airfoil camber length. 3. The propeller according to claim 1, wherein the inboard end of the root section has a curved airfoil camber. 4. A compound helicopter, comprising: a fuselage including a rotor section and a tail section;a main rotor blade disposed at the rotor section and configured to rotate relative to the fuselage to provide a lift force; anda pusher propeller disposed at the tail section and configured to rotate relative to the fuselage to provide thrust, the pusher propeller comprising:a hub;a blade comprising a root section having an inboard end connected to the hub and an outboard end, a tip section at a distance from the hub and having a twist and a body extending in a spanwise direction from the outboard end of the root section to the tip section, an inboard end of the root section having a chordal length and a maximum thickness location defined at approximately 25% of the chordal length, the body having a local twist from the root section to about a 70% span location, which is greater than the twist of the tip section to thereby reduce local angles of attack in a boundary layer region defined in and around the root section. 5. The compound helicopter according to claim 4, wherein the fuselage comprises a wake inducing feature upstream from the pusher propeller. 6. The compound helicopter according to claim 4, wherein the fuselage comprises an axisymmetric wake inducing element. 7. The compound helicopter according to claim 4, wherein the blade is a boundary layer ingesting blade. 8. The compound helicopter according to claim 4, wherein the inboard end of the root section has a chord length that is substantially greater than a thickness thereof and different from an airfoil camber length. 9. The compound helicopter according to claim 4, wherein the inboard end of the root section has a curved airfoil camber. 10. A method of designing a boundary layer ingesting (BLI) blade having a span, the method comprising: forming a tip section to be remote from a hub, the tip section having a twist;forming a root section having an inboard end connectable to the hub and an outboard end, the inboard end of the root section having a chordal length and a maximum thickness location defined at approximately 25% of the chordal length; and,forming a body extending in a spanwise dimension from the outboard end of the root section to the tip section, and forming the body to have a local twist which is greater than the twist of the tip section, the body being up to about a 70% span location with the local twist to reduce local angles of attack in a boundary layer region defined in and around the root section. 11. The method according to claim 10, further comprising forming the inboard end of the root section with a chord length that is substantially greater than a thickness thereof and different from an airfoil camber length. 12. The method according to claim 10, further comprising forming the inboard end of the root section with a curved airfoil camber. 13. The method according to claim 10, further comprising testing the BLI blade in non-ideal conditions. 14. The method according to claim 13, wherein the non-ideal conditions comprise non-uniform free stream airflow velocities upstream of the BLI blade. 15. The propeller according to claim 1, wherein the at least one BLI blade is a pusher propeller blade. 16. The method according to claim 10, wherein the blade is a pusher propeller blade.