The Effects of Angles of Inclination and Incidence on the Aerodynamic Performance of Hyperbolic Paraboloid Kinetic Umbrellas

Abstract

As the risks for coastal hazards increase, traditional countermeasures such as flood walls and storm surge barriers pose a problem, as they hinder access to the beach and diminish coastal beauty. A kinetic hypar umbrella has been proposed as an alternative solution that can provide hybrid benefits of coastal protection and structural art. While hydrostatic and hydrodynamic loads have been tested for the hypar geometry, wind loads have not yet been tested. This thesis seeks to understand the aerodynamic performance of the kinetic umbrellas under varying conditions of inclination and incidence angles. To do so, CRUE20OWT (a wind tunnel at the Forrestal Campus of Princeton University) was validated by comparison with data sets collected at a vetted wind tunnel located at the University of Oviedo. Secondly, a velocity profile was measured for CRUE20OWT to understand the variance in wind across the face of the nozzle. Both tests concluded that the difference between the data sets and the variance in the velocity profile was within the realm of testing errors to vet the wind tunnel, especially to study the behavior trends of the aerodynamic coefficients. The impacts of changing inclination angles on drag and lift coefficients were observed to match the general behavior of airplane wings and its angle of attack. The drag and moment coefficient curves showed a U-shaped curvature with respect to inclination angles, which increased in value as the inclination decreased or increased away from 0 degrees. The lift coefficient showed a more sine-like curvature with a point symmetry about the 0 degrees point. With respect to the angle of incidence, the drag and moment coefficient curves also displayed a U-shaped curvature, increasing in value as the inclination decreased or increased away from 90 degrees. The lift coefficient exhibited a cosine-like curvature where the value decreases as the incidence angle increases from 0 and continues to decrease as the incidence angle increases to 180 degrees. The shape of the curvatures with respect to angle of incidence matches the expected behavior; changing the incidence angle rotation is essentially changing the angle of attack in another axis.