Low pressure ratio fan engine having a dimensional relationship between inlet and fan size
According to an example embodiment, a gas turbine engine assembly includes, among other things, a fan that has a plurality of fan blades. A diameter of the fan has a dimension D that is based on a dimension of the fan blades. Each fan blade has a leading edge. An inlet portion is situated forward of the fan. A length of the inlet portion has a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion. A dimensional relationship of L/D is between about 0.2 and about 0.45.
1. A gas turbine engine assembly, comprising:
a fan including a plurality of fan blades, a diameter of the fan having a dimension D that is based on a dimension of the fan blades, each fan blade having a leading edge; and
an inlet portion forward of the fan, a length of the inlet portion having a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion,
wherein a dimensional relationship of L/D is between 0.2 and 0.45.
2. The assembly of claim 1 , wherein the dimensional relationship of L/D is between 0.25 and 0.45.
3. The assembly of claim 2 , wherein the dimensional relationship of L/D is between 0.30 and 0.40.
4. The assembly of claim 2 , wherein the dimensional relationship of L/D is 0.35.
5. The assembly of claim 1 , wherein
the dimension L is different at a plurality of locations on the inlet portion;
a greatest value of L corresponds to a value of L/D that is at most 0.45; and
a smallest value of L corresponds to a value of L/D that is at least 0.20.
6. The assembly of claim 1 , wherein
the dimension L varies; and
the dimensional relationship of L/D is based on an average value of L.
7. The assembly of claim 1 , wherein
the dimension L varies between a top of the inlet portion and a bottom of the inlet portion; and
the dimensional relationship of L/D is based on a value of L near a midpoint between the top and the bottom of the inlet portion.
8. The assembly of claim 1 , wherein
the leading edges of the fan blades are in a reference plane; and
the dimension L extends along a direction that is perpendicular to the reference plane.
9. The assembly of claim 8 , wherein
the engine assembly has a central axis;
the reference plane is perpendicular to the central axis; and
the dimension L extends along a direction that is parallel to the central axis.
10. The assembly of claim 1 , wherein
the engine assembly has a central axis;
the forward edge on the inlet portion is in a first reference plane;
the leading edges of the fan blades are in a second reference plane; and
the dimension L is measured between a first location where the central axis intersects the first reference plane and a second location where the central axis intersects the second reference plane.
11. The assembly of claim 1 , wherein
the fan is configured to deliver a portion of air into a compressor section and a portion of air into a bypass duct;
a bypass ratio which is defined as a volume of air passing to the bypass duct compared to a volume of air passing into the compressor section being greater than or equal to 8; and
the fan is configured to have a pressure ratio between 1.20 and 1.50 when operating at sea level.
12. The assembly of claim 1 , wherein each of the fan blades is a swept fan blade.
13. The assembly of claim 1 , comprising
a speed change device configured to drive the fan at a speed that is less than an input speed in the speed change device wherein the speed change device is a geared architecture that defines a gear reduction ratio greater than or equal to 2.3.
14. The assembly of claim 1 , wherein
a fan blade tip speed of each of the fan blades is less than 1150 ft/second.
15. A gas turbine engine assembly, comprising:
a fan including a plurality of fan blades, a diameter of the fan having a dimension D that is based on a dimension of the fan blades, each fan blade having a leading edge;
a geared architecture configured to drive the fan at a speed that is less than an input speed in the geared architecture;
a compressor section;
a turbine section configured to drive the compressor section and the geared architecture;
an inlet portion forward of the fan, a length of the inlet portion having a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion; and
wherein a dimensional relationship of L/D is between 0.2 and 0.45.
16. The gas turbine engine assembly of claim 15 , wherein
the dimension L varies; and
the dimensional relationship of L/D is based on an average value of L.
17. The gas turbine engine assembly of claim 15 , wherein
the fan is configured to deliver a portion of air into the compressor section, and a portion of air into a bypass duct;
a bypass ratio between a volume of air passing to the bypass duct and a volume of air passing into the compressor section is greater than or equal to 8; and
the fan is configured to have a pressure ratio less than 1.50 when operating at sea level.
18. The gas turbine engine assembly of claim 15 , wherein
the geared architecture defines a gear reduction ratio greater than or equal to 2.3.
19. The gas turbine engine assembly of claim 15 , wherein
each of the fan blades is a swept fan blade.