Thermal Management Principal Analysis of Hybrid-Electric Aircraft with Turboelectric Propulsion Using Distributed Propulsors
Creators: name:  J. VAN MUIJDEN 
name:   J. AALBERS 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: HYBRID ELECTRIC PROPULSION
AVIATION
EMISSIONS

description: The societal call for environmentally friendly aircraft has put significant emphasis on the study of disruptive greener aircraft concepts and viable alternatives for purely gas turbine powered aircraft [1][2]. One of the options, hybrid-electric propulsion, is currently being investigated within the European project IMOTHEP (Investigation and Maturation Of Technologies for Hybrid-Electric Propulsion) for its merits to reduce fuel consumption. The benefits of such architectures, however, may be counteracted by the thermal management challenges involved [3]. A generic approach is pursued to identify the specific challenges involved and to provide an analysis methodology for the impact assessment of the thermal challenges on overall aircraft design. Within the sketched framework, we limited ourselves to study the thermal management of turboelectric propulsion drive trains for a conservative small-to-medium range aircraft (SMR-con) of size comparable to an Airbus A320neo, based on the notion that the experience gained and the approach used in the problem set-up could be applied to other architectures and aircraft types as well. A specific characteristic of turboelectric propulsion using distributed propulsors is the significant increase of the number of heat sources over the aircraft while the cooling of all those distributed heat sources is not trivial. The principal analysis addressed in this paper comprises the following main elements: A mission profile for the SMR-con, consistent with the prescribed top level aircraft requirements (TLARs), has been provided from the preliminary design work package as input, including thrust per point of the profile; The calculation of operational conditions for each point of the mission profile has been based on a pre-existing routine for the international standard atmosphere (ISA), adjusted for temperature deviations at sea level (ISA+xx); An electrical power distribution architecture based on 24 distributed propulsors driven by 4 generators receiving their mechanical power from two gas turbine engines, adopted from ideas originating from the DRAGON configuration of ONERA [4]; The power demands on components and their associated heat dissipation; The impact of potential failure cases on power demand and resulting asymmetrical heat loads; Basic assumptions regarding the use of heat sinks; Solution of nodal heat equations for the main components; A detailed thermal architecture (component connections, either mechanical, electrical, pneumatic or hydraulic, and cooling loops based on air and/or fuel) as guideline for the principal analysis as well as for the more detailed elaboration by work package partners. The principal analysis is used to obtain a first impression of the expected heat loads, and the capability to maintain component and coolant temperatures within preferred ranges and which additional measures should be taken or alternative options could be embraced. The perspective towards the near future is to improve the thermal management principal analysis based on more detailed modelling of subsets of components by various partners, providing better estimates of heat fluxes and cooling circuit demands. The latter will also provide information regarding additional weight for the required thermal control. Acknowledgment The reported work has been performed within the framework of the IMOTHEP project. The authors acknowledge the valuable discussions with and contributions of IMOTHEP partners to this work as well as the funding received from the European Union Horizon 2020 programme under grant agreement No. 875006. References [1] J.H. Kim, K.S. Kwon, S. Roy, E. Garcia, and D. Mavris, Megawatt-class Turboelectric Distributed Propulsion, Power, and Thermal Systems for Aircraft, AIAA paper 2018-2024, 2018. [2] R. Larkens, A coupled propulsion and thermal management system for hybrid electric aircraft design a case study, MSc. Thesis, Technical University of Delft, October 2020. [3] P. Abolmoali, A. Donovan, S.S. Patnaik, P. McCarthy, D. Dierker, N.Jones, and R. Buettner, Integrated Propulsive and Thermal Management System Design for Optimal Hybrid Electric Aircraft Performance, AIAA paper 2020-3557, 2020. [4] https://www.onera.fr/en/news/how-can-we-reduce-fuel-consumption%3F-dragon