Negative aerodynamic damping causes tower vibrations on turbines with stall rotors. Under certain conditions, these vibrations may rise to a level that causes a shutdown. Active stall turbines have a pitch system, and the objective of the work was to develop pitch control algorithms which would minimise the probability of tower vibrations rising to the shutdown level. The results of a root caus...

Surface pressure data from the National Renewable Energy Laboratory’s “Unsteady Aerodynamics Experiment” were analyzed to characterize the impact of threedimensionality, unsteadiness, and flow separation effects observed to occur on downwind horizontal axis wind turbines (HAWT). Surface pressure and strain gage data were collected from two rectangular planform blades with S809 airfoil crosssect...

Effect of altitude is discussed in the unsteady separation of multi stage rockets. Axisymmetric, unsteady and turbulent Navier stokes equations are solved numerically. The governing equations are split into a hyperbolic inviscid part and a parabolic diffusion part. The hyperbolic part is solved by an explicit second-order time and space of Godunov-type scheme. Moving mesh and moving boundary al...

The joined-wing is a new concept of the airplane wing. The fore-wing and the aft-wing are joined together in a joined-wing. The range and loiter are longer than those of a conventional wing. The joined-wing can lead to increased aerodynamic performance and reduction of the structural weight. In this research, dynamic response optimization of a joined-wing is carried out by using equivalent stat...

The joined-wing is a new concept of the airplane wing. The fore-wing and the aft-wing are joined together in a joined-wing. The range and loiter are longer than those of a conventional wing. The joined-wing can lead to increased aerodynamic performance and reduction of the structural weight. In this research, dynamic response optimization of a joined-wing is carried out by using equivalent stat...

Trailing Edge Flaps on wind turbine blades have been studied in order to achieve fatigue load reduction on the turbine components. We show in this paper how Model Predictive Control can be used to do frequency weighted control of the trailing edge flaps in order to reduce fatigue damage on the blade root. The design model is based on a modal model of the blade structure and a steady state aerod...

A new computational model for the analysis of the suspension system of an innovative concept in vertical-axis wind turbines is introduced. We used this model to study a new concept in extra-large wind-power plants: the VGOT (variable-geometry oval-trajectory) Darrieus wind turbine. In a traditional Darrieus turbine, the blades rotate around a central vertical axis. In the VGOT concept each blad...