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EP-4737740-A2 - GAS TURBINE ENGINE WITH TRIANGULAR-FRAME CONNECTION BETWEEN FAN CASE AND CORE HOUSING

EP4737740A2EP 4737740 A2EP4737740 A2EP 4737740A2EP-4737740-A2

Abstract

A gas turbine engine includes a a fan case (108) surrounding a fan rotor, and a core engine (232) including a low pressure compressor. A rigid connection between the fan case (108) and the core engine (232) includes three triangular-frame connecting members (116) rigidly connected to the fan case (108) at a fan case connection point, and to the core engine (232) at a core engine connection point. The triangular-frame connecting members (116) each are defined by two rigid legs (118, 120) which extend between the fan case (108) and to the core engine (232), along directions each have a component extending radially inwardly and a component in opposed circumferential directions to each other. A plurality of non-structural fan exit guide vanes are provided with an acoustic feature to reduce noise and are rigidly mounted to at the fan case (108) and/or the core engine (232).

Inventors

  • BIFULCO, ANTHONY R.
  • TOPOL, DAVID A.

Assignees

  • RTX Corporation

Dates

Publication Date
20260506
Application Date
20221114

Claims (13)

  1. A gas turbine engine (20) comprising: a fan rotor (106) driven by a fan drive turbine about an axis through a gear reduction (104) to reduce a speed of said fan rotor (106) relative to a speed of said fan drive turbine; a fan case (108) surrounding said fan rotor (106); a core engine (232, 400) having a compressor section (24) including a low pressure compressor (44, 112); three triangular frame connecting members (116), the triangular-frame (116) connecting members each being defined by two rigid legs (118, 120) which extend between said fan case (108) and said core engine (232, 400), along directions each having a component extending radially inwardly and a component in opposed circumferential directions to each other, the two rigid legs (118, 120) being fixed to both the fan case (108) and the core engine (400, 232) at connection points (122, 222; 152, 242); and a plurality of fan exit guide vanes (114) rigidly connected to said fan case (108), and connected to said core engine (232, 400), wherein said two rigid legs (118, 120) in each of said triangular frame connecting members (116) extend from said fan case (108) to said core engine (232, 400) and extend in a direction with a radially inward component and an axially aft direction.
  2. The gas turbine engine (20) as set forth in claims 1, wherein said plurality of fan exit guide vanes (114) include structural and non-structural fan exit guide vanes (114).
  3. A gas turbine engine (20) comprising: a fan rotor (106) driven by a fan drive turbine about an axis through a gear reduction (104) to reduce a speed of said fan rotor (106) relative to a speed of said fan drive turbine; a fan case (108) surrounding said fan rotor (106); a core engine (232, 400) having a compressor section (24) including a low pressure compressor (44, 112), said fan rotor (106) delivering air into a bypass duct (13) defined between said fan case (108) and said core engine (232, 400); a rigid connection between said fan case (108) and said core engine (232, 400) including three triangular-frame connecting members (116) rigidly connected to said fan case (108) at a fan case connection point (122, 222; 152, 242), and to said core engine (232, 400) at a core engine connection point (234) the triangular-frame connecting members (116) each being defined by two rigid legs (118, 120) which extend between said fan case (108) and said core engine (232, 400), along directions each having a component extending radially inwardly and a component in opposed circumferential directions to each other; and a plurality of non-structural fan exit guide vanes (114) being provided with an acoustic feature to reduce noise and being rigidly mounted to the fan case (108) and/or the core engine (232, 400).
  4. The gas turbine engine (20) as set forth in claim 3, wherein said acoustic feature includes said non-structural fan exit guide vanes (114) being formed with chambers (140) and a covering perforated face sheet.
  5. The gas turbine engine (20) as set forth in claim 3 or 4, further comprising structural fan exit guide vanes (114) rigidly secured to both said fan case (108) and said core engine (232, 400), wherein said structural fan exit guide vanes (114) include less than 55% of a total number of fan exit guide vanes including the non-structural fan exit guide vanes.
  6. The gas turbine engine as set forth in claim 5, wherein said structural fan exit guide vanes (114) include 15-30% of the total fan exit guide vanes (129).
  7. The gas turbine engine (20) as set forth in claim 2, 5 or 6, wherein said core engine (232, 400) includes a fan intermediate case (210) forward of said low pressure compressor (44, 112), and said structural fan guide vanes (129) are rigidly connected to said fan intermediate case (210).
  8. The gas turbine engine (20) as set forth in any preceding claim, wherein said low pressure compressor (44, 112) consists of four, five or six stages.
  9. The gas turbine engine (20) as set forth in any preceding claim, wherein the fan case connection point (122, 222; 152, 242) between one of said three triangular frame connecting members and said fan case (108) is at a top dead center position (223), and the connection points (222; 242) to the fan case (108) for the other two of the triangular frame connecting members (116) are on circumferentially spaced sides of a bottom dead center position (224).
  10. The gas turbine engine (20) as set forth in any of claims 1 to 8, wherein the connection point (222; 242) between one of said three triangular frame connecting members (116) and said fan case (108) is at a bottom dead center position (224) and the connection points (122, 222; 152, 242) for the other two of the three triangular frame connecting members (116) are on circumferentially spaced side of a top dead center position (223).
  11. The gas turbine engine (20) as set forth in claim 10, wherein two rigid links connect one of said rigid legs (118, 120) from two of said three triangular frame connecting members (116) spaced circumferentially about said top dead center position (223) to said fan case (108), with said two rigid links being on opposed sides of said top dead center position (223).
  12. The gas turbine engine (20) as set forth in any preceding claim, wherein said core engine (232, 400) includes a compressor intermediate case (232) intermediate said low pressure compressor (44, 112) and a high pressure compressor (52, 230), and said connection points (234) to said core engine (232, 400) are to said compressor intermediate case (232).
  13. The gas turbine engine (20) as set forth in any preceding claim, comprising an outer diameter (d1) of the core engine (232, 400) at the location of the connection points (122; 152) to the rigid legs (118, 120) of said three triangular frame connecting members (116) and a distance (d2) between the legs (118, 120) in each triangular frame connecting member (116) at the connection points (122; 152) where the legs (118, 120) are attached to the core engine (232, 400), and the distance (d2) is greater than the outer diameter (d1).

Description

BACKGROUND OF THE INVENTION This application relates to incorporating frame connections and fan exit guide vanes connections between a fan case and a core housing in a gas turbine engine. Gas turbine engines are known, and typically include a fan delivering air into a bypass duct as propulsion air, and into a core engine housing. The core engine housing houses a compressor section. The air is compressed and delivered into a combustor where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors, driving them to rotate. The turbine rotors in turn rotate the fan and compressor rotors. Historically the fan rotor was fixed to rotate at the same speed as a fan drive turbine rotor, which may also drive a low pressure compressor rotor. More recently a gear reduction has been incorporated between the fan drive turbine and the fan rotor, allowing the fan rotor to rotate at slower speeds than the fan drive turbine. In modem gas turbine engines with such a gear reduction the fan case has been fixed to the core housing through a plurality of fan exit guide vanes, which provide the structural support between the fan case and the inner core housing. SUMMARY OF THE INVENTION According to an aspect of the present invention, a gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of the fan rotor relative to a speed of the fan drive turbine. A fan case surrounds the fan rotor, and a core engine with a compressor section, including a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection is between the fan case and the core engine includes three triangular-frame connecting members rigidly connected to the fan case at a fan case connection point, and to the core engine at a core engine connection point. The triangular-frame connecting members each are defined by two rigid legs which extend between the fan case and to the core engine, along directions each have a component extending radially inwardly and a component in opposed circumferential directions to each other. A plurality of non-structural fan exit guide vanes and the non-structural fan exit guide vanes are provided with an acoustic feature to reduce noise. The non-structural fan exit guide vanes are rigidly mounted to at least one of the fan case and the core engine. Optionally, and in accordance with the above, the acoustic feature includes the non-structural fan exit guide vanes being formed with chambers and a covering perforated face sheet. Optionally, and in accordance with any of the above, there are also structural fan exit guide vanes rigidly secured to both the fan case and the core engine. The structural fan exit guide vanes include greater than 0 and less than 55% of a total number of fan exit guide vanes including the non-structural fan exit guide vane. Optionally, and in accordance with any of the above, the structural fan exit guide vanes include 15-30% of the total fan exit guide vanes. Optionally, and in accordance with any of the above, the low pressure compressor has four to six stages. Optionally, and in accordance with any of the above, there is an outer diameter to the core engine at the location of the connection points to the rigid legs of the three triangular frame connecting members. There is a distance between the legs in each triangular frame connecting member at the connection points where the legs are attached to the core engine. The distance is greater than the outer diameter. Optionally, and in accordance with any of the above, the core engine includes a fan intermediate case forward of the low pressure compressor. The structural fan guide vanes are rigidly connected to the fan intermediate case. Optionally, and in accordance with any of the above, the core engine includes a compressor intermediate case intermediate the low pressure compressor and a high pressure compressor. The connection points between the triangular frame connecting members are to the compressor intermediate case. Optionally, and in accordance with any of the above, the core engine includes a compressor intermediate case intermediate the low pressure compressor and a high pressure compressor. The connection points between the triangular frame connecting members are to the compressor intermediate case. Optionally, and in accordance with any of the above, the connection point between one of the three triangular frame connecting members and the fan case is at a top dead center position. The connection point to the fan case for the other two of the triangular frame connecting member are on circumferentially spaced sides of a bottom dead center position. Optionally, and in accordance with any of the above, the connection point between one of the three triangular frame connecting members and the fan case is at a bottom dead center position. The connection points for the other