Search results for "aerodynamic"
showing 10 items of 66 documents
Take-off aerodynamics in ski jumping
2001
The effect of aerodynamic forces on the force-time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21-33 m s(-1)). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, res…
UAQ4 Levitating Train: Italian Maglev Transportation System
2014
This article illustrates the University of L'Aquila model 4 (UAQ4) Italian maglev train, a transportation system with zero motion resistance (except aerodynamic drag) and greatly reduced energy consumption, approaching zero at a low constant speed. The project is the result of more than 40 years of research in the field of nonconventional highspeed transportation systems. Its technological feasibility has been tested in the laboratory at the University of L'Aquila, Italy.
Monte Carlo simulation for the response analysis of long-span suspended cables under wind loads
2004
This paper presents a time-domain approach for analyzing nonlinear random vibrations of long-span suspended cables under transversal wind. A consistent continuous model of the cable, fully accounting for geometrical nonlinearities inherent in cable behavior, is adopted. The effects of spatial correlation are properly included by modeling wind velocity fluctuation as a random function of time and of a single spatial variable ranging over cable span, namely as a one-variate bi-dimensional (1V-2D) random field. Within the context of a Galerkin`s discretization of the equations governing cable motion, a very efficient Monte Carlo-based technique for second-order analysis of the response is prop…
Forces and flow structures evolution on a car body in a sudden crosswind
2014
A vehicle driver is commonly exposed to strong side air flows, for example when passing through a wind gust. The aerodynamic efforts generated in these situations may induce undesired lateral deviations, which can lead to dramatic effects, if the driver is surprised. In order to simulate a sudden yaw angle change on a moving vehicle, a double wind tunnel facility, adapted from the one of Ryan, Dominy, 2000. Wake Surveys Behind a Passenger Car Subjected to a Transient Cross-wind Gust. SAE Technical Paper No. 2000-01-0874 is developed. Two Windsor car body models, differing from their rear geometry, are analysed. The transient evolution of the side force and yaw moment aerodynamic coefficient…
Wind turbine modeling using the bond graph
2011
Author's version of a chapter in the book: Proceedings of the IEEE International Symposium on Computer-Aided Control System Design. Also available from the publisher at: http://dx.doi.org/10.1109/CACSD.2011.6044572 This paper addresses the problem of bond graph methodology as a graphical approach for modeling wind turbine systems. In this case, we consider the modeling of a wind turbine system with individual pitch control scheme and the interaction with tower motions. Two different bond graph models are presented, one complex and one simplified. Furthermore, the purpose of this paper is not to validate a specific wind turbine model, but rather show the difference between modeling with a cl…
Local DoS applications with micro wind generation systems
2015
In this paper a wind electrical power generation system for Distributed on Site (DoS) applications is proposed. This system was developed and conceived in order to guarantee simple installation, use and service, obtaining a product that can be easily industrialized and put into the market with limited costs. The field of application of such an electrical generation system is addressed towards domestic or at the most toward condominium applications concerning moreover the opportunity of working in addition to combined photovoltaic and solar-thermal systems to enhance the renewable energy generation at house level (DoS). The proposed system has its hot spot in the blades shape, in the wind fl…
On the induced drag reduction due to propeller-wing interaction
1995
AbstractThe aerodynamic interaction between a wing and a couple of propellers in tractor configuration is investigated by means of a model based on the lifting line concept and under the assumption of quasi-steady incompressible motion of inviscid fluid. The ways the propellers influence the wing performances, particularly the induced drag, are analysed. It turns out that the lift increase and the possible drag reduction depend strongly on the direction of the blade rotation and on the propeller distances from midspan, and result from two main effects: the direct propeller induction on the wing and the modification of the lift distribution along the span. An additional nonlinear (mixed) con…
Effects of electrical and mechanical parameters on the transient voltage stability of a fixed speed wind turbine
2011
Abstract In this paper the dynamic behaviour of a wind turbine connected to the grid is examined. The model of the fixed speed wind turbine has been developed with the Simulink simulation tool (Matlab Inc.) It is composed of the induction generator, the shaft system, an aerodynamic model of the wind turbine rotor and the pitch control system. Using this model, a three-phase fault is applied close to the wind turbine and cleared by disconnecting the faulty line. The rigorous implementation of the simulink model allowed the authors to evaluate the exact dependence of various electrical parameters for the induction generator on voltage stability. Furthermore, the effects of wind turbine mechan…
Optimization of a Vehicle Shape by CFD Code
2005
In this paper, fluid dynamics simulations have been executed using a CFD (Computational Fluid Dynamics) commercial code, on a Maserati Biturbo mod. 222 - 1988. At first some surfaces are optimised, choosing the more important ones for the reduction of the resistance, by a manual variation of their geometry, hence a large surface is optimised in an automatic way, by means of an own software, developed in the MatLab environment, returning the optimised surface according to a specific objective function (the resistance in this paper). The aerodynamics resistance results are given under the form of aerodynamics penetration coefficient CD, taking into account the vehicle shape effect, the speed,…
Effects of Electrical Parameters of Induction Generator on the Transient Voltage Stability of a Fixed Speed Wind Turbine
2008
This paper describes the effect of electrical parameters of the induction generator on the transient voltage stability of a fixed speed wind turbine connected to a simple grid; the dynamic behavior of a wind turbine connected to the grid is examined. The model of the fixed speed wind turbine has been developed in the simulation tool Matlab/Simulink. Itpsilas composed by the induction generator, the shaft system, the aerodynamic model of the wind turbine rotor and the pitch control system. Using this model, a three-phases fault is applied close to the wind turbine and cleared by disconnecting the faulted line. The effect of different electrical parameters of the induction generator on the vo…