Effects of Spanwise Controlled Morphing Wing with a Porous Trailing Edge

We investigate the aeroacoustics of a morphing wing equipped with a porous trailing edge. The morphing wing can be twisted dynamically along the span. We perform both experiments and simulations to isolate the effect of surface deformation from trailing-edge porosity. Experiments are being carried out in an anechoic wind tunnel, using a modified NACA 0018 with a spanwise porous region that extends from 0.8c to the trailing edge. Spanwise twist has been preliminary demonstrated using a flat plate wing. Later, the same will be implemented for the NACA airfoil. Dedicated microphones are rigged on top and side of the morphing wing at an adequate distance for accurate signal gathering and low flow interference. The experimentation with morphing dynamics focuses on changes of static angles of attack –between 45° and 135°– across downstream velocities of 0 mph to 40 mph, as well as periodic pitch-plunge motions. This is done to appropriately explore the aeroacoustic impact of spanwise twist motion for a multitude of test cases that combine local –in a specific spanwise section of the wing—changes in the angle of attack with pitching motion. A Fast Fourier Transform (FFT) is then applied to the signal gathered by the two microphones. The resulted frequency trends, dependent on the local Reynolds Number, show that the highest spectral peaks lie in the range of 100 – 1000 Hz, as well as higher tonal clarity at higher velocities, and variations in the uniformity of sound pressure level for different frequency bins. The modified NACA 0018 wing with a porous trailing edge is subject to experimentation with a hot wire set-up in order to gather the velocity and turbulent intensity in the wake and boundary layer of the wing. The experimental data from the porous trailing edge geometry will be compared with acoustics simulations using StarCCM+, where the far-field sound propagation is being modeled with the FW-H equation due to the monopole, dipole, and quadrupole sources. The validation simulation will then serve as a test bed to investigate a wider parameter space containing multiple morphing parameters, wing kinematics and geometry of porous trailing edge. Selected test cases will then be tested in the anechoic wind tunnel.