Airfoil optimization for morphing aircraft

Continuous variation of the aircraft wing shape to improve aerodynamic performance over a wide range of flight conditions is one of the objectives of morphing aircraft design efforts. This is being pursued because of the development of new materials and actuation systems that might allow this shape change. The main purpose of this research is to establish appropriate problem formulations and optimization strategies to design an airfoil for morphing aircraft that include the energy required for shape change. A morphing aircraft can deform its wing shape, so the aircraft wing has different optimum shapes as the flight condition changes. The actuation energy needed for moving the airfoil surface is modeled and used as another design objective. Several multi-objective approaches are applied to a low-speed, incompressible flow problem and to a problem involving low-speed and transonic flow. The resulting solutions provide the best tradeoff between low drag, high energy and higher drag, low energy sets of airfoil shapes. From this range of solutions, design decisions can be made about how much energy is needed to achieve a desired aerodynamic performance. Additionally, an approach to model aerodynamic work, which would be more realistic and may allow using pressure on the airfoil to assist a morphing shape change, was formulated and used as part of the energy objective. These results suggest that it may be possible to design a morphing airfoil that exploits the airflow to reduce actuator energy

Prediction of Swirl Effects on Fan-OGV Interaction Tones

Noise levels predicted for the fan-OGV interaction tones generated by modern high and ultra high bypass ratio aircraft engines are significantly changed when swirl in the interstage region is included in the modelling. An analytical prediction method is used to predict interstage interaction tonal noise levels for an annular duct with uniform flow or swirling flow. It is predicted that swirl effects alter the range of modes that are cut-on, and their corresponding sound power levels in the upstream direction. Results confirm that the inclusion of swirl effects in the modelling of fan-OGV interaction tones is important to improve the prediction of the sound power levels of the upstream propagating modes