MORPHING TURBOFAN ENGINE INLET AT TAKE-OFF CROSS-WIND CONDITIONS

Aeronautical engine inlets are designed as a compromise between low-drag configurations for cruise condition and high airflow incidence angle during take-off and landing. In order to fulfill all the requirements belonging to different operating points, adaptive or morphing structures could be a feasible solution, and they could potentially have a positive impact in terms of aerodynamic performance, therefore leading to a substantial reduction in fuel consumption. However, designing morphing inlets is challenging because of the coupling between aerodynamics and structural analysis which is crucial in order to consider both the feasibility of the adaptive structure and its effects on the aerodynamics of the nacelle. This paper outlines the structural design of an adaptive inlet which features hybrid elastomeric composite materials and a means of active actuation. Since the inlet geometry features both radial and circumferential axes, any change in one axis creates a change in the other resulting in the need of stretchable materials if unwanted steps and gaps are to be prevented for favorable laminar-turbulent transition. To evaluate the aerodynamic effects of such a morphing inlet, a computational fluid-dynamic analysis is coupled with the finite element analysis leading to a "one-way" fluid-structure interaction approach. The goal of the presented method is the definition of an automatic aero-structure coupling framework in order to ease the exploration of a variety of designs over the feasible design space. Results highlight pros and cons of three different design approaches with a particular focus on promising aerodynamic results despite some difficulties in the structural feasibility.