Gas turbine engine with acoustic spacing of the fan blades and outlet guide vanes

A gas turbine engine comprising:

• a core engine comprising a low pressure turbine;
• a gearbox assembly coupled to the low pressure turbine;
• a fan coupled to the gearbox assembly and having a fan diameter and a plurality of fan blades with a blade solidity that is greater than or equal to 0.8 and less than or equal to 2.0;
• a blade effective acoustic length (BEAL) defined as:
• BEAL
• ⁢
• =
• 2
• ⁢
• c
• 2
• S
• ⁡
• (
• 1
• -
• r
• ⁢
• r
• )
• ⁢
• N
• b
• ⁢
• cos
• ⁡
• (
• γ
• )
• wherein c is a chord length of a fan blade of the plurality of fan blades, S is a span of the fan blade, rr is a radius ratio of the fan, γ is a stagger angle of the fan blade, and Nb is the number of the plurality of fan blades;
• a nacelle that includes a fan case that surrounds the fan, the fan case comprising an inlet disposed forward of the fan and an inlet length, wherein the inlet length is an axial distance between a leading edge of one of the plurality of fan blades and the inlet, as measured at a 75% span position of the fan blade;
• a plurality of outlet guide vanes disposed aft of the fan and extending radially between the core engine and the fan case;
• an acoustic spacing from the fan blade trailing edge to an outlet guide vane leading edge;
• an acoustic spacing ratio (ASR) defined as:
• ASR
• =
• 1
• (
• Nv
• Nb
• )
• ·
• As
• BEAL
• wherein As is the acoustic spacing and Nv is the number of the plurality of outlet guide vanes;
• an inlet-to-nacelle (ITN) ratio defined as a ratio of the inlet length to a maximum diameter of the nacelle;
• and
• a plurality of outer guide vanes (OGV), wherein a leading edge of a respective one of the plurality of OGVs defines an angle with respect to an engine centerline, the angle being between 35 and 120 degrees,
• wherein the ASR of the gas turbine engine is 1.5 to 16.0, and the ITN ratio is 0.18 to 0.45.