Aeroelastic Behavior of Noise-Reducing Membranes for Aircraft Lifting Surfaces Part II: Experiments

Abstract

Commercial transport aircrafts generate a large amount of noise during approach and landing. A significant portion of this noise is due to the interaction of vortices and structure at the discontinuity between the wing and the deployed trailing edge flap. One method to reduce this noise is to introduce a thin flexible fairing, known as a continuous mold-line link, that can smoothly connect the edge of the flap to the wing. For design purposes, it is important to analyze the aeroelastic behavior of such fairings, which can be modeled as membranes or panels. Past studies have considered panel flutter with an assortment of boundary conditions, but only recently have efforts begun to consider boundary conditions that apply specifically to the continuous mold-line link, and experimental results are relatively scarce compared to traditionally studied panel flutter configurations. This paper summarizes the results of structural dynamics and aeroelastic experiments for a simplified version of the continuous mold-line link using a candidate material supplied by NASA. The material specimen is clamped in a baffle, and the natural frequencies and mode shapes are measured using impact tests and sine sweep tests. The specimen is also tested in the wind tunnel to measure flutter speed, frequency, and mode shapes. The results are used to validate the theoretical models.