Skip to main content Accessibility help

Off-design performance analysis of hybridised aircraft gas turbine

  • X. Zhao (a1), S. Sahoo (a1), K. Kyprianidis (a1), J. Rantzer (a2) (a3) and M. Sielemann (a2) (a3)...


An advanced geared turbofan with year 2035 technology level assumptions was established and used for the hybridisation study in this paper. By boosting the low-speed shaft of the turbofan with electrical power through the accessory gearbox, a parallel hybrid concept was set up. Focusing on the off-design performance of the hybridised gas turbine, electrical power input to the shaft, defined as positive hybridisation in this context, generally moves the compressor operation towards surge. On the other hand, the negative hybridisation, which is to reverse the power flow direction can improve the part-load operations of the turbofan and minimise the use of compressor handling bleeds. For the pre-defined mission given in the paper, negative hybridisation of descent, approach and landing, and taxi operations with 580 kW, 240 kW and 650 kW, respectively was found sufficient to keep a minimum compressor surge margin requirement without handling bleed.

Looking at the hybridisation of key operating points, boosting the cruise operation of the baseline geared turbofan is, however, detrimental to the engine efficiency as it is pushing the cruise operation further away from the energy optimal design point. Without major modifications to the engine design, the benefit of the hybridisation appears primarily at the thermomechanical design point, the hot-day take-off. With the constraint of the turbine blade metal temperature in mind, a 500kW positive hybridisation at hot-day take-off gave cruise specific fuel consumption (SFC) reduction up to 0.5%, mainly because of reduced cooling flow requirement. Through the introduction of typical electrical power system performance characteristics and engine performance exchange rates, a first principles assessment is illustrated. By applying the strategies discussed in the paper, a 3% reduction in block fuel burn can be expected, if a higher power density electrical power system can be achieved.


Corresponding author


Hide All

A version of this paper was presented at the 24th ISABE Conference in Canberra, Australia, September 2019.



Hide All
1.Strategic Research & Innovation Agenda. 2017 Update |Volume 1, Advisory Council for Aviation Research and Innovation in Europe.
2.Krein, A. and Williams, G. Flightpath 2050: Europe’s vision for aeronautics, Innovation for Sustainable Aviation in a Global Environment: Proceedings of the Sixth European Aeronautics Days, Madrid, Spain, 2012, p 63.
3.Kallas, S. and Geoghegan-Quiin, M. Flightpath 2050: Europe’s Vision for Aviation: Report of the High-Level Group on Aviation Research, European Union, 2011.
4.Bradley, M.K. and Droney, C.K. Subsonic Ultra Green Aircraft Research: Phase I Final Report, National Aeronautics and Space Administration, Langley Research Center, 2011.
5.Bradley, M.K. and Droney, C.K. Subsonic Ultra Green Aircraft Research: Phase 2. Volume 2; Hybrid Electric Design Exploration, NASA,, 2015, CR-2015-218704.
6.Bradley, M. and Droney, C. Subsonic Ultra Green Aircraft Research Phase II: n+ 4 Advanced Concept Development, NASA,, 2012, CR-2012-217556.
7.Seitz, A. Advanced Methods for Propulsion System Integration in Aircraft Conceptual Design, PhD dissertation, Technische Universität München, 2012.
8.SEitz, A., Isikveren, A.T. and Hornung, M. Pre-concept performance investigation of electrically powered aero-propulsion systems, 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, San Jose, California, USA, 2013, p 3608.
9.Seitz, A., et al. Electrically Powered Propulsion: Comparison and Contrast to Gas Turbines, Deutsche Gesellschaft für Luft-und Raumfahrt-Lilienthal-Oberth eV, Berlin, Germany, 2012.
10.Isikveren, A.T., et al. Conceptual studies of universally electric systems architectures suitable for transport aircraft, Deutscher Luft-und Raumfahrt Kongress, DLRK, Berlin, 2012.
11.Stückl, S., Van Toor, J. and Lobentanzer, H. VOLTAIR – the all-electric propulsion concept platform – a vision for atmospheric friendly flight, 28th International Congress of the Aeronautical Sciences (ICAS), Brisbane, Australia, 2012.
12.Jansen, R., et al. Overview of NASA Electrified Aircraft Propulsion (EAP) Research for Large Subsonic Transports, 53rd AIAA/SAE/ASEE Joint Propulsion Conference, Atlanta, Georgia, USA, 2017.
13.Isikveren, A.T., et al. Pre-design strategies and sizing techniques for dual-energy aircraft, Aircr Eng Aerosp Technol: Int J, 2014, 86, (6), pp 525542.
14.Isikveren, A.T., et al. Conceptual studies of future hybrid-electric regional aircraft, 22nd International Symposium on Air Breathing Engines, Phoenix, Arizona, 2015.
15.Isikveren, A.T., et al. Optimization of commercial aircraft using battery-based voltaic-joule/Brayton propulsion, J Aircr, 2016, 54, pp 246261.
16.Pornet, C., et al. Methodology for sizing and performance assessment of hybrid energy aircraft, J Aircr, 2014, 52, (1), pp 341352.
17.Pornet, C. and Isikveren, A. Conceptual design of hybrid-electric transport aircraft, Prog Aerosp Sci, 2015, 79, pp 114135.
18.Pornet, C., Kaiser, S., and Gologan, C. Cost-based flight technique optimization for hybrid energy aircraft, Aircr Eng Aerosp Technol: Int J, 2014, 86, (6), pp 591598.
19.Pornet, C., et al. Integrated fuel-battery hybrid for a narrow-body sized transport aircraft, Aircr Eng Aerosp Technol: Int J, 2014, 86, (6), pp 568574.
20.Lents, C.E., et al. Parallel hybrid gas-electric geared turbofan engine conceptual design and benefits analysis, 52nd AIAA/SAE/ASEE Joint Propulsion Conference, American Institute of Aeronautics and Astronautics, Salt Lake City, Utah, USA, 2016.
21.Freeh, J.E., Steffen, C.J. and Larosiliere, L.M. Off-design performance analysis of a solid-oxide fuel cell/gas turbine hybrid for auxiliary aerospace power, ASME 2005 3rd International Conference on Fuel Cell Science, Engineering and Technology, American Society of Mechanical Engineers, Ypsilanti, Michigan, USA, 2005.
22.Lupelli, L. and Geis, T. A Study on the Integration of the IP Power Offtake System Within the Trent 1000 Turbofan Engine, Msc. Thesis, Pisa University, 2012,
23.Kyprianidis, K.G. Multi-Disciplinary Conceptual Design of Future Jet Engine Systems. PhD dissertation, Cranfield University, 2010.
24.Kyprianidis, K.G. An approach to multi-disciplinary aero engine conceptual design, 23rd International Society for Air Breathing Engines, Manchester, UK, 2017.
25.Kyprianidis, K.G., et al. EVA: A tool for environmental assessment of novel propulsion cycles, ASME. Turbo Expo: Power for Land, Sea, and Air, Volume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric Power 2008, (43123), pp 547556.
26.Hwang, J.T. A Modular Approach to Large-Scale Design Optimization of Aerospace Systems, PhD dissertation, University of Michigan, 2015.
27.Gray, J.S., et al. Automatic evaluation of multidisciplinary derivatives using a graph-based problem formulation in OpenMDAO, 15th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, Atlanta, Georgia, USA, 2014.
28.Jenkinson, L.R., et al. Civil Jet Aircraft Design, Vol. 338, Arnold, 1999, London.
29.Roskam, J. Airplane Design: Part 5-Component Weight Estimation, DARcorporation, 1985, Lawrence, Kansas, USA.
30.Torenbeek, E. Synthesis of Subsonic Airplane Design: An Introduction to the Preliminary Design of Subsonic General Aviation and Transport Aircraft, with Emphasis on Layout, Aerodynamic Design, Propulsion and Performance, Springer Science & Business Media, 2013, Dordrecht, Netherland.
31.ESDU, Estimation of airframe drag by summation of components—principles and examples. Engineering Sciences Data Unit, IHS Group, London, UK, 1997. Standard NO. ESDU-97016.
32.Laskaridis, P. Performance Investigations and Systems Architectures for the More Electric Aircraft. PhD dissertation, Cranfield University, 2004.
33.Kyprianidis, K.G. and Rolt, A.M. On the optimisation of a geared fan intercooled core engine design, ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, American Society of Mechanical Engineers, Dusseldorf, Germany, 2014.
34.Kyprianidis, K.G., Rolt, A.M. and Grönstedt, T. Multidisciplinary analysis of a geared fan intercooled core aero engine, J Eng Gas Turbines Power, 2014, 136, (1), p 011203.
35.Xu, L., Kyprianidis, K.G. and Grönstedt, T.U.J. Optimization study of an intercooled recuperated aero engine, J Propul Power, 2013, 29, (2), pp 424432.
36.Kyprianidis, K.G., et al. Assessment of future aero engine designs with intercooled and inter-cooled recuperated cores, J Eng Gas Turbines Power, 2011, 133, (1), p 011701.
37.Kyprianidis, K.G. and Dahlquist, E. On the trade-off between aviation NOx and energy efficiency. Appl Energy, 2017, 185, pp 15061516.
38.FMI Standard,, 2018.
39.Andersson, C., Åkesson, J. and Führer, C. PyFMI: A python package for simulation of coupled dynamic models with the functional mock-up interface. Technical Report in Mathematical Sciences, 2016, p 40.
40.MODELON, PyFMI,, 2018.
41.Saravanamuttoo, H.I.H., et al. Gas Turbine Theory, 6th ed. Prentice Hall, 2009, Harlow, England; New York.
42.Grieb, H. Projektierung von Turboflugtriebwerken. Technik der Turboflugtriebwerke, Birkhäuser Verlag, 2004, Basel, 826 S.
43.International Aero Engines (IAE), L., Type Certificate Data Sheets and Specifications for PW1100G-JM Series Engines, Federal Aviation Administration, 2018, US.
44.Lolis, P. Development of a preliminary weight estimation method for advanced turbofan engines, PhD dissertation, Cranfield University, 2014.
45.Samuelsson, S., Kyprianidis, K.G. and Grönstedt, T. Consistent conceptual design and performance modeling of aero engines, ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, American Society of Mechanical Engineers, Montreal, Quebec, Canada, 2015.
46.Airbus, S. Aircraft characteristics airport and maintenance planning, Google Scholar, 2005.
47.Walsh, P.P. and Fletcher, P. Gas Turbine Performance, John Wiley & Sons, 2004, Oxford, UK.
48.Guha, A. Optimum fan pressure ratio for bypass engines with separate or mixed exhaust streams, J Propul Power, 2001, 17, (5), pp 11171122.
49.Trawick, D., et al. Development and application of GT-HEAT for the electrically variable engine(TM) design, 55th AIAA Aerospace Sciences Meeting, American Institute of Aeronautics and Astronautics, Grapevine, Texas, USA, 2017.
50.Culley, D.E., Kratz, J.L. and Thomas, G.L. Turbine Electrified Energy Management (TEEM) for enabling more efficient engine designs, 2018 Joint Propulsion Conference, American Institute of Aeronautics and Astronautics, Cincinnati, Ohio, USA, 2018.
51.Brelje, B.J. and Martins, J.R.R.A. Electric, hybrid, and turboelectric fixed-wing aircraft: A review of concepts, models, and design approaches, Prog Aerosp Sci, 2019, 104, pp 119.
52.National Academies of Sciences, E. and Medicine. Commercial Aircraft Propulsion and Energy Systems Research: Reducing Global Carbon Emissions, The National Academies Press, 2016, Washington, DC, p 122.
53.Perullo, C.A., Trawick, D.R. and Mavris, D.N., Assessment of engine and vehicle performance using integrated hybrid-electric propulsion models, J Propul Power, 2016, 32, (6), pp 13051314.
54.Nagata, H. and Chikusa, Y. All-solid-state lithium-sulfur battery with high energy and power densities at the cell level, Energy Technol, 2016, 4, pp 484489.
55.Kyprianidis, K., Future Aero Engine Designs: An Evolving Vision, Intech, 2011, Rijeka, Croatia, pp 324.
56.Kadyk, T., et al. Analysis and design of fuel cell systems for aviation, Energies, 2018, 11, 375.



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed