Turbine engine with composite airfoils
A turbine engine with an engine core defining an engine centerline and comprising a rotor and a stator. The turbine engine including a set of composite airfoils circumferentially arranged about the engine centerline and defining at least a portion of the rotor. An airfoil in the set of composite airfoils including a composite portion extending chordwise between a composite leading edge and a trailing edge and a leading edge protector coupled to the composite portion.
1. A turbine engine, comprising:
an engine core defining an engine centerline and comprising a rotor and a stator;
a first stage of composite airfoils circumferentially arranged about the engine centerline and defining at least a portion of the rotor, a first airfoil of the first stage of composite airfoils comprising:
a first composite portion extending chordwise between a first composite leading edge and a first trailing edge;
a first leading edge protector receiving at least a portion of the first composite leading edge of the first composite portion, the first leading edge protector extending chordwise from a first leading edge towards the first composite portion for a first leading length (FLL); and
the first composite portion and the first leading edge protector together defining an exterior surface of the first airfoil and extending chordwise between the first leading edge and the first trailing edge to define a first chord length (FCL);
a second stage of composite airfoils located downstream of the first stage of composite airfoils and circumferentially arranged about the engine centerline, a second airfoil of the second stage of composite airfoils comprising:
a second composite portion extending chordwise between a second composite leading edge and a second trailing edge;
a second leading edge protector receiving at least a portion of the second composite leading edge of the second composite portion, the second leading edge protector extending chordwise from a second leading edge towards the second composite portion for a second leading length (SLL); and
the second composite portion and the second leading edge protector together defining an exterior surface of the second airfoil and extending chordwise between the second leading edge and the second trailing edge to define a second chord length (SCL);
wherein the first leading length (FLL) and the first chord length (FCL) are related to the second leading length (SLL) and the second chord length (SCL) by a stage protection factor (SPF),
wherein
SPF
=
(
FLL
/
FCL
)
(
SLL
/
SCL
)
and SPF is greater than or equal to 0.7 and less than or equal to 4 (0.7≤SPF≤4);
wherein the first airfoil extends spanwise between a first root and a first tip to define a first span length and the second airfoil extends spanwise between a second root and a second tip to define a second span length less than the first span length.
2. The turbine engine of claim 1 wherein the first stage of composite airfoils and the second stage of composite airfoils include a polymer matrix composite (PMC).
3. The turbine engine of claim 2 wherein at least one of the first leading edge protector or the second leading edge protector is a metallic leading edge protector.
4. The turbine engine of claim 1 wherein the composite airfoils of the first stage of composite airfoils are fan blades and the composite airfoils of the second stage of composite airfoils are outlet guide vanes.
5. The turbine engine of claim 1 wherein the SPF is determined at a location between 20% and 80% of the first span length and the second span length, inclusive of endpoints.
6. The turbine engine of claim 1 wherein the first leading edge protector and the second leading edge protector each comprise a sheath.
7. The turbine engine of claim 1 wherein the first stage of composite airfoils has a first number of airfoils and the second stage of composite airfoils has a second number of airfoils and the first number is different than the second number.
8. The turbine engine of claim 1 wherein the first stage of composite airfoils and the second stage of composite airfoils are configured to rotate.
9. The turbine engine of claim 1 wherein the SPF is greater than or equal to 0.95 and less than or equal to 2.5 (0.95≤SPF≤2.5).
10. The turbine engine of claim 1 wherein the first leading length (FLL) ranges from 6 cm to 19 cm and the second leading length (SLL) ranges from 1.5 cm to 4 cm.
11. The turbine engine of claim 1 wherein the first chord length (FCL) ranges from 24 cm to 77 cm and the second chord length (SCL) ranges from 9.3 cm to 31 cm.
12. A turbine engine comprising:
an engine core defining an engine centerline and comprising a rotor and a stator;
a set of composite airfoils comprising a set of fan blades and a set of outlet guide vanes downstream from the set of fan blades, the set of composite airfoils circumferentially arranged about the engine centerline and defining at least a portion of the rotor, an airfoil of the set of composite airfoils comprising:
a composite portion extending chordwise between a composite leading edge and a trailing edge;
a leading edge protector coupled to the composite portion at the composite leading edge to define a seam, and extending chordwise between a leading edge and the seam to define a leading length (LL); and
the composite portion and the leading edge protector together defining an exterior surface of the airfoil and extending chordwise between the leading edge and the trailing edge to define a chord length (CL);
wherein the leading length (LL) is related to the chord length (CL) by an airfoil protection factor
(
APF
)
=
(
LL
)
(
CL
)
and a first APF (APF1) for the set of fan blades is greater than or equal to 0.2 and less than or equal to 0.30 (0.2≤APF1≤0.3) and a second APF (APF2) for the set of outlet guide vanes is greater than or equal to 0.08 and less than or equal to 0.17 (0.08≤APF2≤0.17).
13. The turbine engine of claim 12 wherein the first airfoil protection factor (APF1) relates to the second airfoil protection factor (APF2) by an expression:
APF
1
APF
2
to define a stage protection factor (SPF), wherein the SPF is greater than or equal to 0.95 and less than or equal to 2.5 (0.95<SPF<2.5).
14. The turbine engine of claim 12 wherein the composite airfoils in the set of composite airfoils extend spanwise between a root and a tip to define a span length and the APF is determined at a location between 20% and 80% of the span length.
15. The turbine engine of claim 12 wherein the leading edge protector overlaps with the composite leading edge to define a sheath.
16. The turbine engine of claim 12 wherein the composite portion is formed from a polymer matrix composite (PMC).
17. The turbine engine of claim 12 wherein the leading edge protector is a metallic leading edge protector.
18. The turbine engine of claim 12 wherein the leading length ranges from 6 cm to 19 cm for the set of fan blades and from 1.5 cm to 4 cm for the set of outlet guide vanes.
19. The turbine engine of claim 12 wherein the chord length ranges from 24 cm to 77 cm for the set of fan blades and from 9.3 cm to 31 cm for the set of outlet guide vanes.