Integrated Sizing and Multi-objective Optimization of Aircraft and Subsystem Architectures in Early Design

Abstract

The aerospace industry's current trend towards novel or More Electric architectures results in some unique challenges for designers due to both a scarcity or absence of historical data and a potentially large combinatorial space of possible architectures. These add to the already existing challenges of attempting to optimize an aircraft design in the presence of multiple possible objective functions while avoiding an overly compartmentalized approach. This paper uses the Integrated Subsystem Sizing and Architecture Assessment Capability to pursue a multi-objective optimization for a Large Twin-aisle Aircraft and a Small Singleaisle Aircraft using the Non-dominated Sorting Genetic Algorithm II with parallel function evaluations. One novelty of the optimization setup is that it explicitly considers the impacts of subsystem architectures in addition to those of traditional aircraft-level design variables. The optimization yielded generations of non-dominated designs in which substantially electrified subsystem architectures were found to predominate. As a first assessment of the impact of epistemic uncertainty on the results obtained, the optimization was re-run with altered sensitivities for the thrust-specific fuel consumption penalties due to shaft-power and bleed air extraction. This analysis demonstrated that the composition of architectures on the Pareto frontier is sensitive to the secondary power extraction penalties, but more so for the Small Single-aisle Aircraft than the Large Twin-aisle Aircraft.

Algorithm for Optimizing the Design Parameters of a Light Transport Aircraft at the Stage of Preliminary Design

“…According to the obtained results, shown in figures (5,6), it is obvious that takeoff weight and fuel efficiency coefficient are more sensitive to wing aspect ratio than to its taper ratio. The optimal aspect ratio obtained under the condition of the minimum fuel efficiency coefficient is greater than that under the condition of the minimum takeoff mass, because the fuel efficiency ratio is more sensitive to the aerodynamic characteristics of the aircraft, which increases alongside with aspect ratio.…”

“…The selection of rational parameters at the preliminary design stage is crucial as it establishes the foundation for subsequent design decisions and ultimately determines the aircraft's overall performance. The academic literatures on this topic focus on several key areas, including aircraft performance, structural design, weight estimation, and optimization methods [1][2][3][4][5][6].…”

Evaluating Optimal Paths for Aircraft Subsystem Electrification in Early Design

“…In an effort to reduce the size of the combinatorial space, previous studies on subsystem architectures [7,12] considered subsystem electrification bundles or packages using reasoning based on rules with regard to a natural electrification ordering due to technology maturation status. For instance, the predefined strategy for Actuation Function Packages (AFPs) included the Primary Flight Control Actuators (PFCA, that include elevators, ailerons, and rudder), Trimmable Horizontal Stabilizer Actuation (THSA), Spoiler Actuation (SPLA), leading and trailing edge High Lift Device Actuation (HLDA), Nose Wheel Steering System (NWSS), Landing Gear Actuation System (LGAS), Wheel Brake System (WBS), and Thrust Reverser Actuation System (TRAS).…”

“…In studies on integrated sizing and multi-objective optimization of aircraft with more-electric architectures by Rajaram et al [12,13], substantially electrified subsystems were found to dominate the Pareto frontier over conventional designs. Their study assumed that all subsystems could be electrified at once.…”