LOW PRESSURE RATIO FAN ENGINE HAVING A DIMENSIONAL RELATIONSHIP BETWEEN INLET AND FAN SIZE
A gas turbine engine assembly according to an example of the present disclosure includes, among other things, 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, a turbine section configured to drive the geared architecture, a compressor section including a first compressor and a second compressor, and an inlet portion 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;
a geared architecture configured to drive the fan;
a turbine section configured to drive the geared architecture;
a compressor section including a first compressor and a second compressor, the first compressor including fewer stages than the second compressor; 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 about 0.2 and about 0.45.
2 . The assembly of claim 1 , wherein the dimensional relationship of L/D is between about 0.25 and about 0.45.
3 . The assembly of claim 2 , wherein the dimensional relationship of L/D is between about 0.30 and about 0.40.
4 . 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.
5 . 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.
6 . 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.
7 . 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 generally perpendicular to the reference plane.
8 . The assembly of claim 7 , wherein
the engine has a central axis;
the reference plane is generally perpendicular to the central axis; and
the dimension L extends along a direction that is parallel to the central axis.
9 . The assembly of claim 1 , wherein
the engine has a central axis;
the forward edge on the inlet portion is in a 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.
10 . The assembly of claim 1 , wherein the first compressor is upstream of the second compressor.
11 . The assembly of claim 10 , 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 which is defined as a volume of air passing to the bypass duct compared to a volume of air passing into the compressor section is greater than or equal to about 10;
the fan is a low pressure ratio fan having a pressure ratio between about 1.20 and about 1.50; and
the geared architecture defines a gear reduction ratio greater than or equal to about 2.3.
12 . The assembly of claim 10 , wherein the turbine section includes a fan drive turbine configured to drive the fan and a first turbine configured to drive one of the first compressor and the second compressor, the first turbine including fewer stages than the fan drive turbine.
13 . The assembly of claim 12 , wherein the dimensional relationship of L/D is between about 0.30 and about 0.40.
14 . The assembly of claim 13 , wherein the first turbine includes at least two (2) stages.
15 . The assembly of claim 13 , wherein the first compressor includes three (3) stages, and the second compressor includes (8) stages.
16 . 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 turbine section configured to drive the geared architecture; 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, the inlet portion being free of any bifurcations forward of the fan, a dimensional relationship of L/D being less than or equal to about 0.45.
17 . The gas turbine engine assembly of claim 16 , wherein the fan is a single fan stage.
18 . The gas turbine engine assembly of claim 17 , wherein the dimensional relationship of L/D is at least about 0.20.
19 . The gas turbine engine assembly of claim 18 , wherein the dimensional relationship of L/D is between about 0.30 and about 0.40.
20 . The gas turbine engine assembly of claim 19 , 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, is greater than or equal to about 10;
the fan defines a pressure ratio less than about 1.50; and
the geared architecture defines a gear reduction ratio greater than or equal to about 2.3.