The focus of this Doctoral research is on the use of alternative fuels in advanced hybrid electric (parallel or series) power plant architectures for future aircraft propulsion. This research programme spans for 3 years and is in close collaboration with Rolls-Royce plc (fully funded by Rolls-Royce plc via the UTC at Cranfield).
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The aviation industry is recognized as the most rapidly growing source of CO2 emissions given that by 2035 global traffic is forecasted to be twice as large as the one in 2016. Therefore its environmental impact is becoming a concern and measures to reduce it are investigated and assessed. Organizations such as the Advisory Council for Aeronautics Research in Europe (ACARE) have published some very ambitious goals for aviation to achieve in order to tackle this environmental challenge by 2050.

It is apparent that large reductions in CO2 and NOx cannot be achieved by conventional cycles, hence the aviation industry is assessing new types of propulsion systems and aircraft configurations. Out of these candidates, hybrid-electric propulsion has been identified as a promising technology for significantly reducing aviation emissions. Additionally, a potential increase in the system's efficiency is expected due to the flexibility that multiple sources of energy and power may offer. An electrical propulsion system can be coupled within the gas turbine engine in many ways, depending on the configuration adopted. Two different architectures are the main options: a connection in series or in parallel. In series configurations, a turboshaft is connected to a generator, which converts mechanical power into electrical. Then, energy is conveyed to motor-driven fans. At the same time, a percentage of the energy required is also fed by batteries, which are interconnected between the generator and the motor. Thus, the overall power provided is handled by two systems at once.

One of the advantages of such a drive-train is that the combustion engine, is indirectly connected to the propulsors, can always operate at its maximum efficiency while the same is true for the propulsors (e.g. fans), cutting down fuel consumption. Furthermore, since peak power demands are managed by batteries, the gas-turbine can be sized smaller. In the case of parallel architecture, external mechanical power provided by an electric power train is added through one of the spools. In more detail, an electric motor fed by energy stored in batteries is connected to the low-pressure spool of the gas turbine. A power converter has to be set among the line, in order to convert DC current to AC and control its rotational speed by changing current frequency. This architecture benefits from a higher safety redundancy level due to power line independency. Also, it is easier to implement in today’s aircraft configurations, while given the absence of the generator and the distributed fans, it weighs less than its series counterpart. Nonetheless, energy has to be stored in batteries, which are characterized by low energy density compared to kerosene.

It would be within the scope of this PhD programme to explore all the above power train options for different aircraft/propulsion system configurations and identify relevant design trade-offs, whilst also looking at a range of alternative aviation fuels.

At a glance

  • Application deadline30 Dec 2019
  • Award type(s)PhD
  • Start dateAs soon as possible
  • Duration of award3 years
  • EligibilityEU, UK
  • Reference numberSATM127


Professor Vassilios Pachidis

Director, Rolls-Royce UTC in Aero Systems Design, Integration & Performance

Head, Gas Turbine Engineering Group, Centre for Propulsion Engineering

Entry requirements

Applicants should have a first-class or upper second-class degree in engineering or a related area. An aerospace background would be a distinct advantage as would experience in aero-engine performance, simulation, modelling, computational fluid dynamics and fluid mechanics. The candidate should be self-motivated, have good communication skills for regular interaction with other stakeholders, with an interest for industrial research. 


To be eligible for full funding, applicants must be a UK or EU national. Other nationalities may be considered.

About the sponsor

The UTC is hosted by the Centre for Propulsion Engineering at Cranfield, testimony of the Centre’s global visibility and extensive links with industry. The UTC is the cornerstone of Cranfield’s relationship with Rolls-Royce, acting also as a supporting ‘pillar’ to the new Aerospace Integration Research Centre (AIRC) at Cranfield (a £35M partnership between Rolls-Royce, AIRBUS, HEFCE and Cranfield). It currently enrols more than 6 Senior Academics (at Professorial and Senior Lecturer level), 5 Lecturers, 17 Research Fellows, 15 PhD students and 30 MSc students from the Centre’s Thermal Power MSc course. Placed between academia and industry, it carries out research with a strong scientific and industrial relevance. The core competence of the UTC is its ability to undertake detailed modelling studies and performance simulations involving aero-thermal, multi-disciplinary models to improve and extend our understanding of power plant, aircraft and related systems’ integrated performance within, but also at the edges, of the operating envelope. There is also a large experimental activity supported by Rolls-Royce. The UTC provides a unique experience and set of skills to those students who choose to undertake their research work with Rolls-Royce at MSc or PhD level. Over recent years more than 100 Thermal Power MSc students have been recruited by Rolls-Royce, and more than 20 UTC PhD graduates (7 last year alone).

Cranfield Doctoral Network

Research students at Cranfield benefit from being part of a dynamic, focused and professional study environment and all become valued members of the Cranfield Doctoral Network. This network brings together both research students and staff, providing a platform for our researchers to share ideas and collaborate in a multi-disciplinary environment. It aims to encourage an effective and vibrant research culture, founded upon the diversity of activities and knowledge. A tailored programme of seminars and events, alongside our Doctoral Researchers Core Development programme (transferable skills training), provide those studying a research degree with a wealth of social and networking opportunities.

How to apply

For further information please contact:

Professor Vassilios Pachidis


T: 44 (0)1234 754663

If you are eligible to apply for this research studentship, please complete the online application form

School of Aerospace, Transport and Manufacturing

T: 44 (0)1234 758540