Aerospace Mechanics

Aerospace Mechanics

Investigation of the Impact of Bypass Ratio and Fan Pressure Ratio on the Performance Components of a Turbofan Engine in Cruise and Descent Flight Conditions

Document Type : Propulsion and Heat Transfer

Author
amir mahdavi
PhD Student, Shahid Sattari University, Tehran, Iran
10.47176/ECDJ.2025.1550
Abstract
Optimizing the performance of turbofan engines across various flight phases is a fundamental challenge in aerospace propulsion design, primarily due to its direct impact on operational costs and propulsion stability. This study presents a comparative analysis of the effects of key design parameters, including bypass ratio (BPR) and fan pressure ratio (FPR), on engine performance indicators during two distinct flight regimes: cruise and descent. The primary innovation of this research lies in the simultaneous evaluation of the engine's thermodynamic behavior in these two phases, identifying how the sensitivity of thrust components and efficiency metrics shifts in response to design choices. To this end, a thermodynamic model was developed in MATLAB to simulate parameters such as thrust, thrust-specific fuel consumption (TSFC), and thermal, propulsive, and overall efficiencies. The results indicate that increasing the bypass ratio significantly mitigates the performance disparity between cruise and descent phases. Specifically, the propulsive efficiency gap between these two phases decreases from 8% in a pure turbojet configuration to 4% at a bypass ratio of 8. Furthermore, as the bypass ratio increases, the rate of fuel consumption reduction in the descent phase becomes more pronounced compared to the cruise phase, reaching a difference of 3.15% at a BPR of 8. These findings underscore the critical importance of integrating descent-phase characteristics into the optimization process of high-bypass-ratio engines.

Graphical Abstract

Investigation of the Impact of Bypass Ratio and Fan Pressure Ratio on the Performance Components of a Turbofan Engine in Cruise and Descent Flight Conditions

Highlights

[1]     Jakubowski R. Study of the effects of heat exchanger location on turbofan engine performance. Adv Sci Technol Res J. 2024;18(3):282-293. doi: 10.12913/22998624/189464.

[2]     Imani A, Anjomrouz A, Rasti A. Reducing the specific fuel consumption of a micro-turbojet engine by converting it into a micro-turbofan engine. J Fluid Mech Aerodyn. 2024;12(1):49-63. DOR:https://dor.isc.ac/dor/20.1001.1.23223278.1402.12.1.5.4[In Persian].

[3]     Imani A. Design and simulation of a selector controller to control a micro-turbofan engine in flight mission. J Fluid Mech Aerodyn. 2024;13(2):163-172.DOR:https://dor.isc.ac/dor/20.1001.1.23223278.1403.13.2.12.0 [In Persian].

[4]     Mattingly JD. Elements of gas turbine propulsion. New York: McGraw-Hill; 1996. (McGraw-Hill series in aeronautical and aerospace engineering).

[5]     Huff DL. Noise reduction technologies for turbofan engines. Cleveland (OH): NASA Glenn Research Center; 2007. Report No.: NASA/TM—2007-214495.

[6]     [6] Jakubowski R. Analysis of turbofan engine design modification to add inter-turbine combustor. J KONES Powertrain Transp. 2015;22(3):95-102. doi: 10.5604/12314005.1165977.

[7]     Merril GL. Turbofan propulsion for general aviation. SAE Int J. 1973;32(3):23-65. doi: 10.4271/730287.

[8]     Skavdahl H, Zimbrick RA. Very high bypass ratio engines for commercial transport propulsion. In: 16th Congress of the International Council of the Aeronautical Sciences (ICAS); 1988 Aug 28–Sep 2; Jerusalem, Israel. 1988.

[9]     Lu P, Burken JJ. Controlling aircraft with engine thrust only: nonlinear challenges. Nonlinear Anal Theory Methods Appl. 1999;35(1):21-35. doi: 10.1016/S0362-546X(97)00650-3.

[10]   Thiery G, Simon H, Pascal S. Theoretical analysis of environmental and energetic performance of very high temperature. Thermodin Sci. 1999;380:442-481. doi: 10.1016/S0035-3159(99)80024-X.

[11]   Ikaza D, Rausch C. Thrust vectoring for Eurofighter-the first steps. Air Space Eur. 2000;2(1):92-95. doi: 10.1016/S1290-0958(00)80020-5.

[12]   Svoboda C. Turbofan engine database as a preliminary design tool. Aircr Des. 2000;3(1):17-31. doi: 10.1016/S1369-4332(99)00007-0.

[13]   Montazeri M, Foroozannejad M, Yousefi Dastjerdi A, Bordbar A. Integrated simulation and control of turbojet engine dynamics and fixed-wing airplane flight dynamics. J Aerosp Mech. DOR:https://dor.isc.ac/dor/20.1001.1.26455323.1403.20.4.7.52025;20(4):103-116. [In Persian].

[14]   Bartel M, Young TM. Simplified thrust and fuel consumption models for modern two-shaft turbofan engines. J Aircr. 2008;45(4):1450-1456. doi: 10.2514/1.34351.

[15]   Yunusov S, Labendik V, Kopytov E. Turbofan thrust control on flight information in aircraft engine diagnostic system. Ultragarsas. 2006;60(3):20-23. doi: 10.5755/j01.u.60.3.11195.

[16]   Mahmoodi M, Pirkandi J, Jahromi M. Aerodynamic design and optimization of a 10 stage compressor and a 3 stage fan of a low bypass ratio turbofan engine. J Fluid Mech Aerodyn. 2024;13(2):163-172. DOR:https://dor.isc.ac/dor/20.1001.1.23223278.1403.13.1.10.6[In Persian].

[17]   Marszalek N. The impact of thermodynamic parameters of the turbofan engine with ITB on its performance. Combust Engines. 2020;182(3):45-51. doi: 10.19206/CE-2020-307.

[18]   Baklacioglu T, Cavcar M. Aero-propulsive modelling for climb and descent trajectory prediction of transport aircraft using genetic algorithms. Aeronaut J. 2014;118(1199):65-79. doi: 10.1017/S000192400000894X.

[19]   Goulos I, Pachidis V, Pilidis P. Aerodynamic design of separate-jet exhausts for future civil aero-engines—part II: design space exploration, surrogate modeling, and optimization. J Eng Gas Turbines Power. 2016;138(8):081202. doi: 10.1115/1.4032652.

[20]   Dankanich A, Peters D. Turbofan engine bypass ratio as a function of thrust and fuel flow [master’s thesis / report]. St. Louis (MO): Washington University in St. Louis; 2017.

[21]   Jakubowski R. Two-combustor turbofan engine performance analysis. J KONES Powertrain Transp. 2014;21(3):141-148. doi: 10.5604/12314005.1133917.

[22]   Solomon A. Performance study of N+3 turbofan engine model with several types of fuels using NPSS [master’s thesis / report]. St. Louis (MO): Washington University in St. Louis; 2022.

[23]   Ogur E, Karakoc TH. Performance assessment of ammonia as a turbofan engine fuel during various altitude levels. Energy. 2024;290:132714. doi: 10.1016/j.energy.2024.132714.

[24]   Gao R, Khani Aminjan K, Heidari M, Rahmanivahid P, Salahinezhad M, Khashehchi M. High-bypass ratio, separate-exhaust turbofan engine: study on flight Mach number and inlet temperature. J Chin Soc Mech Eng. 2025;46(2):185-193. doi: 10.6108/JCSME.2025.02.003.

[25]   Farokhi S. Aircraft propulsion: cleaner, leaner, and greener. 3rd ed. Hoboken (NJ): John Wiley & Sons; 2021

Keywords
Turbofan By
Pass Ratio Fan Pressure Ratio Performance Cruise and Descent
Subjects


Smiley face

[1]     Jakubowski R. Study of the effects of heat exchanger location on turbofan engine performance. Adv Sci Technol Res J. 2024;18(3):282-293. doi: 10.12913/22998624/189464.
[2]     Imani A, Anjomrouz A, Rasti A. Reducing the specific fuel consumption of a micro-turbojet engine by converting it into a micro-turbofan engine. J Fluid Mech Aerodyn. 2024;12(1):49-63. DOR:https://dor.isc.ac/dor/20.1001.1.23223278.1402.12.1.5.4[In Persian].
[3]     Imani A. Design and simulation of a selector controller to control a micro-turbofan engine in flight mission. J Fluid Mech Aerodyn. 2024;13(2):163-172.DOR:https://dor.isc.ac/dor/20.1001.1.23223278.1403.13.2.12.0 [In Persian].
[4]     Mattingly JD. Elements of gas turbine propulsion. New York: McGraw-Hill; 1996. (McGraw-Hill series in aeronautical and aerospace engineering).
[5]     Huff DL. Noise reduction technologies for turbofan engines. Cleveland (OH): NASA Glenn Research Center; 2007. Report No.: NASA/TM—2007-214495.
[6]     [6] Jakubowski R. Analysis of turbofan engine design modification to add inter-turbine combustor. J KONES Powertrain Transp. 2015;22(3):95-102. doi: 10.5604/12314005.1165977.
[7]     Merril GL. Turbofan propulsion for general aviation. SAE Int J. 1973;32(3):23-65. doi: 10.4271/730287.
[8]     Skavdahl H, Zimbrick RA. Very high bypass ratio engines for commercial transport propulsion. In: 16th Congress of the International Council of the Aeronautical Sciences (ICAS); 1988 Aug 28–Sep 2; Jerusalem, Israel. 1988.
[9]     Lu P, Burken JJ. Controlling aircraft with engine thrust only: nonlinear challenges. Nonlinear Anal Theory Methods Appl. 1999;35(1):21-35. doi: 10.1016/S0362-546X(97)00650-3.
[10]   Thiery G, Simon H, Pascal S. Theoretical analysis of environmental and energetic performance of very high temperature. Thermodin Sci. 1999;380:442-481. doi: 10.1016/S0035-3159(99)80024-X.
[11]   Ikaza D, Rausch C. Thrust vectoring for Eurofighter-the first steps. Air Space Eur. 2000;2(1):92-95. doi: 10.1016/S1290-0958(00)80020-5.
[12]   Svoboda C. Turbofan engine database as a preliminary design tool. Aircr Des. 2000;3(1):17-31. doi: 10.1016/S1369-4332(99)00007-0.
[13]   Montazeri M, Foroozannejad M, Yousefi Dastjerdi A, Bordbar A. Integrated simulation and control of turbojet engine dynamics and fixed-wing airplane flight dynamics. J Aerosp Mech. DOR:https://dor.isc.ac/dor/20.1001.1.26455323.1403.20.4.7.52025;20(4):103-116. [In Persian].
[14]   Bartel M, Young TM. Simplified thrust and fuel consumption models for modern two-shaft turbofan engines. J Aircr. 2008;45(4):1450-1456. doi: 10.2514/1.34351.
[15]   Yunusov S, Labendik V, Kopytov E. Turbofan thrust control on flight information in aircraft engine diagnostic system. Ultragarsas. 2006;60(3):20-23. doi: 10.5755/j01.u.60.3.11195.
[16]   Mahmoodi M, Pirkandi J, Jahromi M. Aerodynamic design and optimization of a 10 stage compressor and a 3 stage fan of a low bypass ratio turbofan engine. J Fluid Mech Aerodyn. 2024;13(2):163-172. DOR:https://dor.isc.ac/dor/20.1001.1.23223278.1403.13.1.10.6[In Persian].
[17]   Marszalek N. The impact of thermodynamic parameters of the turbofan engine with ITB on its performance. Combust Engines. 2020;182(3):45-51. doi: 10.19206/CE-2020-307.
[18]   Baklacioglu T, Cavcar M. Aero-propulsive modelling for climb and descent trajectory prediction of transport aircraft using genetic algorithms. Aeronaut J. 2014;118(1199):65-79. doi: 10.1017/S000192400000894X.
[19]   Goulos I, Pachidis V, Pilidis P. Aerodynamic design of separate-jet exhausts for future civil aero-engines—part II: design space exploration, surrogate modeling, and optimization. J Eng Gas Turbines Power. 2016;138(8):081202. doi: 10.1115/1.4032652.
[20]   Dankanich A, Peters D. Turbofan engine bypass ratio as a function of thrust and fuel flow [master’s thesis / report]. St. Louis (MO): Washington University in St. Louis; 2017.
[21]   Jakubowski R. Two-combustor turbofan engine performance analysis. J KONES Powertrain Transp. 2014;21(3):141-148. doi: 10.5604/12314005.1133917.
[22]   Solomon A. Performance study of N+3 turbofan engine model with several types of fuels using NPSS [master’s thesis / report]. St. Louis (MO): Washington University in St. Louis; 2022.
[23]   Ogur E, Karakoc TH. Performance assessment of ammonia as a turbofan engine fuel during various altitude levels. Energy. 2024;290:132714. doi: 10.1016/j.energy.2024.132714.
[24]   Gao R, Khani Aminjan K, Heidari M, Rahmanivahid P, Salahinezhad M, Khashehchi M. High-bypass ratio, separate-exhaust turbofan engine: study on flight Mach number and inlet temperature. J Chin Soc Mech Eng. 2025;46(2):185-193. doi: 10.6108/JCSME.2025.02.003.
[25]   Farokhi S. Aircraft propulsion: cleaner, leaner, and greener. 3rd ed. Hoboken (NJ): John Wiley & Sons; 2021