Paulo Eduardo C. S. Magalhaes

Conceptual Optimal Design of Airliners with Noise Constraints

Noise generated by airplane during the takeoff and landing flight phases is a matter of increasing concern for both aviation and aeronautical industries. Air traffic is steadily increasing and airports are operating close to their capacity limit. Airlines are under high pressure from communities surrounding airports to operate quieter airplanes and/or change their operating procedures. For this reason, quieter airplanes will be welcome by the airlines and comply to the expected traffic growth. From an airplane manufacturer point of view, the reduction of noise generated by airplane to acceptable levels is a very challenging task. It is to be expected that such drastic noise reductions will not be achieved by merely working on mitigating noise sources on the airplane in isolated form. Instead, the interactions of noise sources as well as shielding effects have to be taken into account. Airplane noise becomes a configuration issue and thus has to be considered in the conceptual design phase. Quieter airplanes could be charged with some penalties like performance degradation and higher fuel consumption, in the latter case generating more pollutants. In order to carry out the design for a quieter airplane considering all this aspects, it is useful to incorporate a noise assessment methodology into a multi-disciplinary design and optimization framework. This approach is justified because an airplane should not be designed considering just a few requirements. Field performance, stability and control, operating costs, manufacturing costs, passenger comfort, embedded technology, all this must be simultaneously considered for designing an airliner that airlines need. A Parametric Airliner Noise Prediction Architecture (PANPA) has been developed at Instituto Tecnologico de Aeronautica (ITA), which is able to predict noise levels generated by an airliner along arbitrary flight trajectories. The related noise levels are estimated for an observer positioned on ground, as required by certification authorities. The module takes into account major airframe and engine noise sources, as well as diverse effects on sound propagation. A multi-disciplinary integrated conceptual airplane design framework, designated AIDMIM, has been in development for some time at ITA. This framework features a modular structure written in MATLAB® language, which allows for manageable incorporation of additional disciplines and analysis methods to the overall design process. PANPA was integrated into AIDMIN and some design tasks with and without noise constraints were carried out.

Conceptual Optimal Design of Environmentally Friendly Airliners: AReview of Available Methodologies and their Integration into a ConsistentFramework for Everyday Use

Airplane design involves complex system integration and must comply with a set of requirements, which are set up by certification authorities, customers, manufacturing, and that coming from market studies. From the traditional perspective of an airline, an interesting airplane is one that is capable of generating the highest revenue with minimum cost-a maximum profit airplane. In later years, however, the airline industry is swiftly broadening its consideration of what constitutes a nice-to-buy airplane. Not only economics but also environmental considerations are taking part in fleet-planning considerations-a trend spurred by environmental-aware passengers. In a move to comply with this trend, airplane conceptual design has incorporated methodologies for preliminary assessment of airplane noise and emissions. As more approaches become available to address these issues, the choice between the most suitable methodologies becomes tougher. The present work analyzes some methodologies in order to select a subset of them. The objective is the evaluation of such methodologies and their integration into a framework to airliner conceptual design. In order to test the design methodologies and the optimization techniques, the authors selected two test airplane categories: first, a long range, transcontinental jet; and a mid-size regional jet. Design tasks based on optimization with noise footprint, direct operational cost, and emission profile or a combination of them as objectives are presented and analyzed.