Influence of Parametric Modelling of Wing Subsystems on the Aircraft Design and Performance

Abstract

Aircraft design methodologies have been significantly developing from the past few years with the advancements in knowledge based techniques. These methods enable the storage of design knowledge and rules, and reuse them to create different types of designs, thus preventing the designer to perform repetitive tasks. Tasks such as parametric modelling of components, such as the aircraft wing can be automated by storing the modelling processes and the design rules in a knowledge base. With this process, variants of the wing with different geometric parameters can then be generated in a short duration by simply varying certain top-level requirements. It is necessary to extend these design techniques to model aircraft systems in the conceptual design stage. This, not only decreases the time of design realisation but also presents a scope to assess the effects of various inter-dependencies due to systems and make appropriate changes, in the early stages of aircraft design. Developing and demonstrating a framework which aids to assess the influence of the wing subsystems, namely the flight control actuators, fuel tanks and anti-ice elements; on the aircraft design and performance in the conceptual design stage is the aim of the thesis.

This thesis presents a combination of physics based and knowledge based design methodologies to size the wing subsystems and position them in the airframe. Consequently, the methods are integrated into the conceptual aircraft design process to enable multidisciplinary design with supporting domains. The methods are aimed to aid the design of conventional systems architectures and More Electric Aircraft (MEA) systems architectures as well. With these methodologies, the Systems Model Generator (SMG) application is developed in Python to facilitate semi-automatic wing subsystems sizing and orientation in the airframe based on top-level aircraft requirements, initial aircraft design parameters and system specific parameters. The subsystem models generated with the proposed methodology for short-medium range civil transport aircraft are verified and validated as well. Knowledge based systems and subsystems selection are implemented to facilitate semi-automated systems, subsystems and architecture selection, based on the aircraft configuration and systems specific requirements. Methods for automatic iterative fuel tanks sizing and intersection detection are implemented to further reduce the overall design time and make the tool more suitable for integrated sizing.

With the multidisciplinary design framework, the conceptual parametric models, volume, mass, power consumption and position of the subsystems in the airframe are generated and propagated in the conceptual aircraft design stage; thus bridging the conceptual and the preliminary design stages. In the proposed framework, the domains of aircraft design generation, systems selection and sizing, subsystems selection and sizing, engine sizing and mission simulation are considered for the multidisciplinary design process. The domains are integrated with the DLR CPACS-RCE framework.

A case study to demonstrate the process of integrated parametric subsystems sizing of the aircraft, with the proposed framework is presented. The aim of this case study is to assess the influence of the MEA systems architecture relative to the conventional systems architecture for a short-medium range transport aircraft, similar to the Airbus A320-200. In this case study, the quantitative influence of the subsystems' parameters on the aircraft design and performance parameters is determined and analysed. The subsystems' parameters constitute the mass, power consumption, volume and location of the subsystems in the airframe and the aircraft design parameters constitute the aircraft masses such as the overall empty mass and the fuel mass for the mission. The generation and propagation of the design and performance parameters of the aircraft through each domain of the framework are presented and analysed as well with the case study. In this case study, it is observed that the MEA systems architecture results in a lower mission fuel mass relative to the conventional systems architecture by nearly 2.3\%. Furthermore, these results are compared with literature and observed to be in the similar range of 2-7\%. Thus, the validated aircraft design framework presented in this thesis enables to substantially increases and propagate the design knowledge of aircraft systems, in the early design stages.