Author: F. Diaz, J. Gavalda, J. G Kawall, J.F. Keffer, and F. GiraltPublication: Universitat de BarcelonaYear Published: 1983 Wind turbines must withstand harsh environments that induce many stress cycles into their components. A numerical analysis package is used to illustrate the sobering variability in predicted fatigue life with relatively small changes in inputs. The variability…
Author: Matthias Kinzel, Daniel Araya and John DabiriPublication: Physics of FluidsYear Published: 2015 Experimental results from three different full scale arrays of vertical-axis wind turbines (VAWTs) under natural wind conditions are presented. The wind velocities throughout the turbine arrays are measured using a portable meteorological tower with seven, vertically staggered, three-component ultrasonic anemometers. The power…
Author: John DabiriPublication: IOPScienceYear Published: 2007 Aquatic animals swimming in isolation and in groups are known to extract energy from the vortices in environmental flows, significantly reducing muscle activity required for locomotion. A model for the vortex dynamics associated with this phenomenon is developed, showing that the energy extraction mechanism can be described by simple…
Author: Clara O’Farrell and John O. DabiriPublication: Cambridge UniversityYear Published: 2014 The formation and pinch-off of non-axisymmetric vortex rings is considered experimentally. Vortex rings are generated using a non-circular piston–cylinder arrangement, and the resulting velocity fields are measured using digital particle image velocimetry. Three different nozzle geometries are considered: an elliptical nozzle with an aspect…
Author: Clara O’Farrell and John O. DabiriPublication: Cambridge UniversityYear Published: 2012 The nonlinear perturbation response of two families of vortices, the Norbury family of axisymmetric vortex rings and the Pierrehumbert family of two-dimensional vortex pairs, is considered. Members of both families are subjected to prolate shape perturbations similar to those previously introduced to Hill’s spherical…
Author: Clara O’Farrell and John O. DabiriPublication: Cambridge UniversityYear Published: 2014 Inviscid models for vortex rings and dipoles are constructed using nested patches of vorticity. These models constitute more realistic approximations to experimental vortex rings and dipoles than the single contour models of Norbury and Pierrehumbert, and nested contour dynamics algorithms allow their simulation with…
Author: Sayed Hossein Hezeveh, Elie Bou-ZeidPublication: Physical Review FluidsYear Published: 2018 Vertical-axis wind turbines (VAWTs) are the subject of renewed interest due to the potential for higher power generation per unit land used, as well as their lower center of mass (the generator is at the bottom of tower), which renders them favorable for offshore…
Author: Y. Bazilevs, A. Korobenko, X. Deng, J. Yan, M. Kinzel, John DabiriPublication: J. Appl. Mech.Year Published: 2014 Full-scale, 3D, time-dependent aerodynamics and fluid–structure interaction (FSI) simulations of a Darrieus-type vertical-axis wind turbine (VAWT) are presented. A structural model of the Windspire VAWT (Windspire energy, http://www.windspireenergy.com/) is developed, which makes use of the recently proposed…
Author: Sanjay Mittal, Bhaskar KumarPublication: J. Fluid Mech.Year Published: 2002 The fatigue analysis of a wind turbine component typically uses representative samples of cyclic loads to determine lifetime loads. In this paper, several techniques currently in use are compared to one another based on fatigue life analyses. The generalized Weibull fitting technique is used to…
Author: Dan Henningson, Martin BerggrenPublication: KTHYear Published: 2005 These lecture notes has evolved from a CFD course (5C1212) and a Fluid Mechanics course (5C1214) at the department of Mechanics and the department of Numerical Analysis and Computer Science (NADA) at KTH. Erik Stalberg and Ori Levin has typed most of the LATEX formulas and has…