Ultra-High Bypass Ratio Turbofan for Next-Generation Large Aircraft
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Ultra-High Bypass Ratio Turbofan for Next-Generation Large Aircraft Nicholas Turo-Shields, Sebastian Perkinson, Shashank Kashyap, Chris Vodney, Maunik Patel, Gerardo Martinez, Aditya Anilkumar AAE/ME 538 14 December 2018 Table of Contents Nomenclature 3 1 Abstract 4 2 Design Requirements 4 3 Baseline Engine 4 4 Team Structure 8 5 Design Methodology 8 5.1 Choice of Architecture . .8 5.2 BPR and Core Sizing . .9 5.2.1 Initial Core Scaling (constant fan mass flow) .......................9 5.2.2 Bypass Scaling (constant core scale) ............................9 5.2.3 Evaluation of Design for Takeoff . 10 5.2.4 Sizing for Cruise . 11 5.2.5 Further Improvements . 12 5.3 Gearbox . 12 5.4 Compressors . 13 5.4.1 LP Compressor (Fan) . 13 5.4.2 IP Compressor (Booster) . 15 5.5 LP Turbine . 16 5.5.1 Optimization of Specific Fuel Consumption . 17 5.5.2 Optimization of Core Flow . 17 5.5.3 Final Results for LP Turbine . 18 5.6 Materials . 19 5.7 Engine Cycle Improvements . 21 5.8 Risks and Concerns . 22 6 Our Engine Solution 23 7 Off-Design Analysis 24 7.1 Off-Design Operating Point . 24 7.2 Mission Profile . 25 7.3 Flight Envelope . 26 7.4 Mission Points . 28 7.5 Results . 28 8 Trade-off Study 30 8.1 Parametric Study . 31 8.2 Baseline Engine . 31 8.3 Geared Solution . 32 9 Limits of Analysis 33 10 Appendix A - Velocity Triangles 34 11 Appendix B - GasTurb Engine Configuration (Final GTF) 35 12 Appendix C - Material Properties 40 2 Symbols and Abbreviations A Area (m2) L Low-pressure spool alt Altitude (m) LP- Low-pressure amb Ambient LPC LP compressor (fan) ax Axial LPT LP Turbine Bld Bleed M Mach number BPR Bypass ratio N Spool speed corr Corrected NGV Nozzle guide vane (of a turbine) C Compressor o Outer Cl Cooling P Total pressure (kPa) d Diameter (m) prop Propulsion dH Enthalpy difference R Gas constant dp Design point rel Relative f Fuel RNI Reynolds number index far Fuel-air-ratio s Static FN Net thrust (kN) S NOx NOx severity parameter h Enthalpy SFC g H High-pressure spool Specific fuel consumption kN·s HdlBld Handling bleed t Tip (blade) or time HP- High-pressure (compressor, turbine) T Total temperature (K) i Inner U Blade (tip) velocity (m/s) IP- Intermediate-pressure V Velocity (m/s) IPC IP compressor (booster) W Mass flow (also denotedm _ ) (kg/s) Station Designations 0 Ambient 41 First turbine stator exit = rotor inlet 1 Engine inlet 42 HPT exit before addition of cooling air 2 First compressor inlet 43 HPT exit after addition of cooling air 21 Inner stream fan exit 44 IPT inlet 13 Outer stream fan exit 45 IPT stator exit 16 Bypass exit 46 IPT exit before addition of cooling air 18 Bypass nozzle throat 47 IPT exit after addition of cooling air 24 IP compressor exit 48 LPT inlet 25 HP compressor inlet 49 LPT exit before addition of cooling air 3 HPC exit, cold side heat exchanger inlet 5 LPT exit after addition of cooling air 31 Burner inlet 8 Nozzle throat 4 Burner exit 3 1 Abstract Boeing and Airbus are considering replacement engines for their 787, A380, and A350 airplanes. Newer engine technologies enable the core to operate more efficiency and deliver more power. Higher bypass ratio engines are being considered to improve propulsive efficiency. An engine model has been provided. The task is to keep the same core but design an improved LP/IP stage that utilizes the existing core to improve the propulsive efficiency over the mission of the aircraft. The performance characteristics and total fuel consumption should be estimated over the mission. Attention should be paid to weight, dimensions, stage aerodynamic compatibility, and technical feasibility (Materials, etc). Operating cost and maintenance cost (limited stage count, reduced blade count) should be considered. 2 Design Requirements • Select an engine architecture (1/2/3-spool, geared, etc.) • Flight Design Points { Takeoff: sea-level { Cruise: 12,190 m at Mach 0.85 { Range: 17,600 km • Takeoff Thrust ≥ 374 kN • Takeoff Power ≥ 200 kW • Overall Pressure Ratio (OPR, p3=p2): 60 • Turbine Inlet Temperature (T4): 1930 K • Power off-take: 200 kW • If a geared design is chosen, assume a mass of 0.00482768 kg/kW 3 Baseline Engine The baseline engine we are comparing our redesigned engine against is the Rolls-Royce Trent XWB. Table 1: Basic design features of the baseline engine. Engine Type Axial, turbofan Number of fan/booster/compressor stages 1, 8, 6 Number of HP/IP/LP turbine stages 1, 2, 7 Combustor type Annular Maximum net thrust at sea-level 396 kN g SFC at cruise at Mach 0.85 & 12.19 km altitude 18.2 kN·s Overall pressure ratio at max. power 50 Bypass ratio 9.3 Max. envelope diameter 2.997 m Max. envelope length 4.064 m Dry weight less tail-pipe 5,445 kg Turbine Inlet Temperature 1784 K 4 Table 2: Input to GasTurb of the baseline engine model. Property Unit Value Comment Intake Pressure Ratio 1 No (0) or Average (1) Core dP/P 1 Inner Fan Pressure Ratio 1.4 Outer Fan Pressure Ratio 1.43 Core Inlet Duct Pressure Ratio 1 IP Compressor Pressure Ratio 6.3 Compressor Interduct Pressure 0.985 Ratio HP Compressor Pressure Ratio 5.76 Bypass Duct Pressure Ratio 0.975 Inlet Corr. Flow W2Rstd kg/s 1442.92 Inlet corrected flow rate standard day Design Bypass Ratio 9.3 Burner Exit Temperature K 1783 Burner Design Efficiency 0.9995 Burner Partload Constant 1.6 Used for off design only Fuel Heating Value MJ/kg 43.124 Overboard Bleed kg/s 0 Power Offtake kW 50 HP Spool Mechanical Efficiency 0.99 IP Spool Mechanical Efficiency 0.999 LP Spool Mechanical Efficiency 0.999 Burner Pressure Ratio 0.96 Ipt Interd. Ref. Press. Ratio 0.992 Lpt Interd. Ref. Pressure Ratio 1 Turbine Exit Duct Press Ratio 0.99 Figure 1: Baseline engine station diagram and flows, 3-spool. 5 Figure 2: Baseline engine model schematic, 3-spool. Table 3: GasTurb summary of the baseline model engine at sea-level. W T P WRstd Station kg/s K kPa kg/s FN = 396.03 kN amb 288.15 101.325 TSFC = 7.8416 g/(kN*s) 2 1442.919 288.15 101.325 1442.920 WF = 3.10549 kg/s 13 1302.830 322.15 144.895 963.323 s NOx = 2.28101 21 140.089 320.77 141.855 105.575 BPR = 9.3000 22 140.089 320.77 141.855 105.575 Core Eff = 0.5278 24 140.089 562.99 893.687 22.201 Prop Eff = 0.0000 25 140.089 562.99 880.281 22.539 P3/P2 = 50.041 3 131.684 921.84 5070.420 4.707 P2/P1 = 1.00000 31 116.274 921.84 5070.420 P22/P21 = 1.00000 4 119.380 1783.00 4867.603 6.182 P25/P24 = 0.98500 41 126.384 1739.15 4867.603 6.463 P4/P3 = 0.96000 42 126.384 1406.66 1706.924 P44/P43 = 0.99200 43 134.789 1378.42 1706.924 P48/P47 = 1.00000 44 134.789 1378.42 1693.269 P6/P5 = 0.99000 45 139.693 1359.02 1693.269 18.154 P16/P13 = 0.97500 46 139.693 1156.75 785.978 P16/P6 = 0.69135 47 141.794 1151.55 785.978 P5/P2 = 2.03708 48 141.794 1151.55 785.978 36.542 V18/V8,id= 0.43099 49 141.794 857.50 206.407 A8 = 0.51485 m² 5 143.195 855.67 206.407 121.132 A18 = 4.83610 m² 8 143.195 855.67 204.343 122.356 XM8 = 1.00000 18 1302.830 322.15 141.272 988.024 XM18 = 0.70583 Bleed 0.000 921.84 5070.420 WBld/W2 = 0.00000 -------------------------------------------- Efficiencies: isentr polytr RNI P/P CD8 = 1.00000 Outer LPC 0.9103 0.9147 1.000 1.430 CD 18 = 0.92331 Inner LPC 0.8900 0.8951 1.000 1.400 PWX = 50.00 kW IP Compressor 0.8991 0.9210 1.233 6.300 WlkLP/W25= 0.00000 HP Compressor 0.9290 0.9430 3.912 5.760 WBld/W25 = 0.00000 Burner 0.9995 0.960 Loading = 100.00 % HP Turbine 0.9094 0.8989 5.888 2.852 e442 th = 0.87880 IP Turbine 0.9061 0.8980 2.722 2.154 WCHN/W25 = 0.05000 LP Turbine 0.9193 0.9059 1.528 3.808 WCHR/W25 = 0.06000 -------------------------------------------- WCIN/W25 = 0.03500 HP Spool mech Eff 0.9900 Nom Spd 1199 9 rpm WCIR/W25 = 0.01500 IP Spool mech Eff 0.9990 Nom Spd 5113 rpm WCLR/W25 = 0.01000 LP Spool mech Eff 0.9990 Nom Spd 2472 rpm -------------------------------------------- hum [%] war0 FHV Fuel 0.0 0.00000 43.124 Generic 6 Table 4: GasTurb summary of the baseline model engine at cruise conditions. W T P WRstd Station kg/s K kPa kg/s FN = 57.90 kN amb 216.65 18.760 TSFC = 18.1933 g/(kN*s) 2 492.903 248.02 30.097 1539.549 WF = 1.05338 kg/s 13 447.947 279.78 41.233 1084.669 s NOx = 1.18576 21 44.956 278.46 40.456 110.684 BPR = 9.9642 22 44.956 278.46 40.456 110.684 Core Eff = 0.5791 24 44.956 520.79 265.829 23.037 Prop Eff = 0.8113 25 44.956 520.79 261.536 23.415 P5/P2 = 2.21582 EPR 3 42.258 882.93 1629.562 4.600 P2/ P1 = 1.00000 31 37.313 882.93 1629.562 P22/P21 = 1.00000 4 38.367 1792.32 1567.317 6.186 P25/P24 = 0.98385 41 40.614 1746.30 1567.317 6.464 P4/P3 = 0.96180 42 40.614 1414.47 551.684 P44/P43 = 0.99206 43 43.312 1383.78 551.684 P48/P47 = 1.00000 44 43.312 1383.78 547.305 P6/P5 = 0.99001 45 44.885 1363.03 547.305 18.073 P16/P13 = 0.96831 46 44.885 1162.65 255.689 P16/P6 = 0.60473 47 45.559 1156.85 255.689 P5/P2 = 2.21582 48 45.559 1156.85 255.689 36.175 V18/V8,id= 0.45171 49 45.559 866.77 66.689 A8 = 0.51485 m² 5 46.009 864.50 66.689 121.080 A18 = 4.83610 m² 8 46.009 864.50 66.023 122.302 XM8 = 1.00000 18 447.947 279.78 39.926 1120.173 XM18 = 1.00000 Bleed 0.000 882.93 1629.562 WBld/W2 = 0.00000 -------------------------------------------- Efficiencies: isentr polytr RNI P/P CD8 = 1.00000 Outer LPC 0.7361 0.7476 0.355 1.370 CD18 = 0.96000 Inner LPC 0.7197 0.7312 0.355 1.344 PWX = 50.00 kW IP Compressor 0.8089 0.8512 0.416 6.571 WlkLP/W25= 0.00000 HP Compressor 0.9100 0.9285 1.275 6.231 WBld/W25 = 0.00000 Burner 0.9974 0.962 Loading = 281.88 % HP Turbine 0.9092 0.8988 1.886 2.841 e442 th = 0.88048 IP Turbine 0.9042 0.8961 0.877 2.141 WCHN/W25 = 0.05000 LP Turbine 0.9015 0.8855 0.495 3.834 WCHR/W25 = 0.06000 -------------------------------------------- WCIN/W25 = 0.03500 HP Spool mech Eff 0.9900 Speed 11999 rpm WCIR/W25 = 0.01500 IP Spool mech Eff 0.9990 Speed 5219 rp m WCLR/W25 = 0.01000 LP Spool mech Eff 0.9990 Speed 2673 rpm -------------------------------------------- hum [%] war0 FHV Fuel 0.0 0.00000 43.124 Generic Figure 3: Baseline engine thermodynamic cycle.