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The synergistic combination of two promising engine architectures for future aero engines is presented. The first is the Composite Cycle Engine, which introduces a piston system in the high pressure part of the core engine, to utilize closed volume combustion and high temperature capability due to instationary operation. The second is the Intercooled Recuperated engine that employs recuperators to utilize waste heat from the core engine exhaust, and intercooler to improve temperature levels for recuperation and to reduce compression work. Combinations of both architectures are presented and investigated for improvement potential with respect to specific fuel consumption, engine weight and fuel burn against a turbofan. The Composite Cycle alone provides a 15.6% fuel burn reduction against a turbofan. Options for adding intercooler were screened, and a benefit of up to 1.9% fuel burn could be shown for installation in front of piston system through a significant, efficiency-neutral weight decrease. Waste heat can be utilized by means of classic recuperation to the entire core mass flow before the combustor, or alternatively on the turbine cooling bleed or a piston engine bypass flow that is mixed again with the main flow before the combustor. As further permutation, waste heat can be recovered either after the low pressure turbine - with or without sequential combustion - or between the high pressure and low pressure turbine. Waste heat recovery after the low pressure turbine was found to be not easily feasible or tied to high fuel burn penalties due to unfavourable temperature levels, even when using sequential combustion or intercooling. Feasible temperature levels could be obtained with inter-turbine waste heat recovery, but always resulted in at least 0.3% higher fuel burn compared to the non-recuperated baseline under the given assumptions. Consequently, only the application of an intercooler appears to provide a considerable benefit for the examined thermodynamic conditions in the low fidelity analyses of various engine architecture combinations with the specific heat exchanger design. Since the obtained drawbacks of some waste heat utilization concepts are small, innovative waste heat management concepts coupled with the further extension of the design space and the inclusion of higher fidelity models may achieve a benefit and motivate future investigations. Received 7 June 2017; revised 18 March 2018; accepted 22 March 2018. A version of this paper was presented at the ISABE 2017 Conference, 3-8 September 2017, Manchester, UK.

New commercial aero engines for 2050 are expected to have lower specific thrusts for reduced noise and improved propulsive efficiency, but meeting the ACARE Flightpath 2050 fuel-burn and emissions targets will also need radical design changes to improve core thermal efficiency. Intercooling, recuperation, inter-turbine combustion and added topping and bottoming cycles all have the potential to improve thermal efficiency. However, these new technologies tend to increase core specific power and reduce core mass flow, giving smaller and less efficient core components. Turbine cooling also gets more difficult as engine cores get smaller. The core-size-dependent performance penalties will become increasingly significant with the development of more aerodynamically efficient and lighter-weight aircraft having lower thrust requirements. In this study the effects of engine thrust and core size on performance are investigated for conventional and intercooled aeroengine cycles. Large intercooled engines could have 3%–4% SFC improvement relative to conventional cycle engines, while smaller engines may only realize half of this benefit. The study provides a foundation for investigations of more complex cycles in the EU Horizon 2020 ULTIMATE programme. This paper will be presented at the ISABE 2017 Conference, 5-8 September 2017, Manchester, UK.