Multidisciplinary Design Optimization Framework with Coupled Derivative Computation for Hybrid Aircraft

Abstract

Hybrid-electric aircraft are a potential way to reduce the environmental footprint of aviation. Research aimed at this subject has been pursued over the last decade; nevertheless, at this stage, a full overall aircraft design procedure is still an open issue. This work proposes to enrich the procedure for the conceptual design of hybrid aircraft found in literature through the definition of a multidisciplinary design optimization (MDO) framework aimed at handling design problems for such kinds of aircraft. The MDO technique has been chosen because the hybrid aircraft design problem shows more interaction between disciplines than a conventional configuration, and the classical approach based on multidisciplinary design analysis may neglect relevant features. The procedure has been tested on the case study of a single-aisle aircraft featuring hybrid propulsion with distributed electric ducted fans. The analysis considers three configurations (with 16, 32, and 48 electric motors) compared with a conventional baseline at the same 2035 technological horizon. To demonstrate the framework's capability, these configurations are optimized with respect to fuel and energy consumption. It is shown that the hybrid-electric concept consumes less fuel/energy when it flies on short range due to the partial mission electrification. When one increases the design range, penalties in weight introduced by hybrid propulsion overcome the advantages of electrified mission segment: the range for which hybrid aircraft have the same performance of the reference conventional aircraft is named the "breakdown range." Starting from this range, the concept is no longer advantageous compared to conventional aircraft. Furthermore, a tradeoff between aerodynamic and propulsive efficiency is detected, and the optimal configuration is the one that balances these two effects. Finally, multiobjective optimization is performed to establish a tradeoff between airframe weight and energy consumption.

A Review of Concepts, Benefits, and Challenges for Future Electrical Propulsion-Based Aircraft

“…A tightly coupled modeling environment is built between the propulsion system and the trajectory analysis with a simplified approximated aerodynamic model. A multidisciplinary (MDO) technique was implemented with the integration of the Fixed Aircraft Sizing Tool (FAST) sizing tool to OpenMDAO framework to conduct design optimization in a distributed hybrid electric system [161]. pyOptSparse is a similar optimization framework with Sparse Nonlinear Optimizer (SNOPT) utilized in association with the SUAVE aircraft sizing tool for the design study of 19 PAX aircraft, with BLI and DEP effects [162].…”

“…The tool runs atop the OpenMDAO framework and utilizes the analytic derivative of the models to perform gradient based optimization. [161,163] PEGASUS Design A low-order multidisciplinary optimization environment is used for sizing the aircraft. The FLOPS tool is used for computing the aerodynamics, propulsion weight, performance and geometry data.…”

Upper trust bound feasibility criterion for mixed constrained Bayesian optimization with application to aircraft design

“…This section presents an aircraft design application where the SEGO solvers lead to a significant improvement. We target to design a hybrid aircraft, featuring distributed electric propulsion [19,42,43], the related concept of such aircraft is shown in Fig. 15.…”

“…The fixed-wing aircraft sizing tool (FAST) [44] is used to explore this aircraft concept and is fully coded in Python. It is based on engineering methods, to have reliable results with low computa- tional cost [45].…”

THEA-CODE: a design tool for the conceptual design of hybrid-electric aircraft with conventional or unconventional airframe configurations

“…In reference [23,24] a conceptual design of hybrid-electric aircraft has been presented. Some authors have defined a multidisciplinary optimization framework, as in [25], to design a single aisle aircraft with distributed electric fans. All the previous works only consider hybridization of tube-and-wing configuration whereas hybridization of disruptive configurations (e.g.…”