Aeroservoelasticity Investigation with Panel Method

When designing a new technological device that is affected by aerodynamic forces, it is almost common practice to model it with 3D CFD methods to study the design and to decide in which direction further developments should be taken. An elastic wing aircraft is considered to be a particularly complex model in which the number of parameters to be tested is too large to consider calculations that take tens or even hundreds of hours per simulation for each factor. In the industry, "high fidelity" Finite Volume Method simulations have become the general practice. Instead we use a so called panel method, where modelling the entire flow field is not necessary, only the surface mesh of the investigated body has to be generated. With this method the computational demand decreases drastically, but we know that there’s no such thing as a free lunch. In addition to reducing the calculation time, we need to put the accuracy of the results on the other arm of the balance. The panel method solves only one Laplace equation for the full velocity potential, therefore it cannot model the additional drag due to the viscous medium

Experimental and Computational Analysis of a 3D Printed Wing Structure

Correct prediction of aeroelastic response is a crucial part in designing flutter or divergence free aircrafts within a designated flight envelope. The aeroelastic analysis includes specifically tailoring the design in order to prevent flutter (passive control) or eliminate it by applying input on control surfaces (active control). High-fidelity models such as coupled Computational Fluid Dynamics (CFD) - Computational Structural Dynamics (CSD) can obtain full structural and aerodynamic behavior of a deformable aircraft. However, these models are so large that pose a significant challenge from the control systems design perspective. Thus, the development of an aeroelastic modeling software that can be used for further control design is the main motivation of this thesis. In addition, an aeroelastic analysis of a topologically optimized wing geometry will serve as a validation tool of the software. Initially, a 3D printed prototype of the wing is validated against static deformation tests as well as dynamic Ground Vibration Tests (GVT). The developed model is compared against the commercial software Nastran/Patran. Further plans include experimental aerodynamic test of 3D printed wing in the new Embry-Riddle Aeronautical University’s (ERAU) wind tunnel to validate the proposed model

Fluid–structure interaction of symmetrical and cambered spring-mounted wings using various spring preloads and pivot point locations

The fluid–structure interaction of a pivoting rigid wing connected to a spring and subjected to freestream airflow in a wind tunnel is presented. Fluid–structure interactions can, on the one hand, lead to undesirable aerodynamic behaviour or, in extreme cases, to structural failure. On the other hand, improved aerodynamic performance can be achieved if a controlled application within certain limitations is provided. One application is the reduction of drag of road vehicles at higher speeds on a straight, while maintaining downforce at lower speeds during cornering. Conversely, another application concerns increased downforce at higher windspeeds, enhancing vehicle stability. In our wind tunnel experiments, the angle of incidence of the spring-mounted wing is either increased or decreased depending on the pivot point location and spring torque. Starting from a specified initial angle, the aerodynamic forces overcome a pre-set spring preload at incrementally increased freestream velocity. Reynolds numbers at a range of Re = 3 × 104 up to Re = 1.37 × 105 are considered. The application of a symmetrical NACA 0012 and a cambered NACA 6412 airfoil are tested in the wind tunnel and compared. For both airfoils mounted ahead of the aerodynamic centre, stable results were achieved for angles above 15 and below 12 degrees for the symmetrical airfoil, and above 25 and between 10 and −2 degrees for the cambered airfoil. Unsteady motions were observed around the stall region for both airfoils with all spring torque settings and also below −2 degrees for the cambered airfoil. Stable results were also found outside of the stall region when both airfoils were mounted behind the aerodynamic centre, although the velocity ranges were much smaller and highly dependent on the pivot point location. An analysis is reported concerning how changing the spring torque settings at each pivot point location effects performance. The differences in performance between the symmetrical and cambered profiles are then presented. Finally, an evaluation of the systems’ effects was conducted with conclusions, future improvements, and potential applications