A database of flutter characteristics for simple low and medium aspect ratio wings at low speeds

Flutter is a catastrophic aeroelastic instability that must be prevented for all engineering structures operating in an airflow. Several standard methods exist for predicting the flutter onset airspeed and flutter frequency of lifting surfaces, such as the Doublet Lattice Method and the Vortex Lattice Method. Such techniques can be applied by means of industrial standard aeroelastic software packages, such as Nastran and ZAERO. Nevertheless, researchers are constantly developing new aeroelastic prediction software for various applications and with different capabilities. Such developments must be validated using either standard benchmark solutions or experimental data. While such benchmarks do exist, they are mostly targeted at compressible flows around aircraft wings. The purpose of the present work is to present a new experimental database of flutter airspeeds and frequencies for a significant number of simple wings at low subsonic airspeeds. The wings feature a variety of aspect and taper ratios, focusing in the low and medium aspect ratio range, from 2 to 5.4.

This paper presents results from the wind tunnel experiments, including flutter speeds, flutter frequencies, as well as natural frequency and damping ratio variation with airspeed for all wings. Predictions for the flutter characteristics of the wings are obtained from the Vortex Lattice method and compared to the experimental measurements. It is shown that the predictions are very good, except for the wings with Aspect Ratios close to 2, for which errors in flutter speed of up to 28% were obtained. The flutter frequency was predicted accurately for all wings.