Francesca Lupi

Francesca Lupi
Ruhr-Universität Bochum | RUB

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28
Publications
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174
Citations

Publications

Publications (28)
Article
As the size of modern wind turbines increases, the phenomenon of vortex resonance, which occurs at lower critical speeds due to lower natural frequencies of larger turbines, becomes more significant. Vortex shedding in the wake of a slender structure is still not fully investigated, particularly with regard to the Reynolds number mismatch between s...
Article
Full-text available
From July 2021, a full-scale measurement campaign is carried out on two wind turbine towers with smooth surfaces (k/D ≈ 1.0·10- ⁶ ). Tower response (through accelerations) and wind pressure on the surface are measured. Throughout the one-year monitoring period, there were challenges in transferring full-scale data into a ready-to-use VIV data set....
Article
To model the aeroelasticity in vortex-induced vibrations (VIV) of slender tubular towers, this paper presents an approach where the aerodynamic damping distribution along the height of the structure is calculated not only as a function of the normalized lateral oscillation but also considering the local incoming wind velocity ratio to the critical...
Chapter
The paper studies tower vibrations in closely spaced group arrangements due to vortex excitation and interference galloping. The ever-growing development of the wind energy industry has recently led to an in-depth examination of the subject, particularly with regard to the transport of towers for offshore wind turbines. Due to the low natural frequ...
Chapter
Full-text available
The estimation of vortex shedding load is essential for the prediction of Vortex-Induced Vibration (VIV) on slender bodies. The application of the VIV model to a full-scale slender tower, such as wind turbine towers and chimneys, depends on the estimation of actual vortex shedding load under field conditions. This paper aims to provide insight on t...
Conference Paper
Full-text available
This paper reports of the ongoing measurement campaign on two prototype wind turbine towers of the Siemens Gamesa Renewable Energy in Østerild, Denmark. The latest evaluation and measurement results in this paper are also presented during the 97th CICIND conference in Paphos, Cyprus, which includes the evaluation of the measured pressure distributi...
Conference Paper
Full-text available
From July 2021, a full-scale measurement campaign is carried out on two wind turbine towers with smooth surfaces (k/D ~ 1.0∙10-6). Tower response (through accelerations) and wind pressure on the surface are measured. Throughout the one-year monitoring period, there were challenges in transferring full-scale data into a ready-to-use VIV data set. Fo...
Conference Paper
Full-text available
The estimation of vortex shedding load is essential for the prediction of Vortex-Induced Vibration (VIV) on slender bodies. The application of the VIV model to a full-scale slender tower, such as wind turbine towers and chimneys, depends on the estimation of actual vortex shedding load under field conditions. This paper aims to provide insight on t...
Article
Ultimate limit state and fatigue analyses of slender structures in vortex-induced vibrations require knowledge of aerodynamic damping in the lock-in range. The aerodynamic damping depends primarily on the shape of the cross section. The paper provides an experimental database of aerodynamic damping functions for different shapes, with a focus on sh...
Article
Large across-wind response of tall flexible structures becomes an increasing concern due to the significant nonlinear aero-elastic effect. The nonlinear aerodynamic damping, which is in phase of time-variant structural velocity, is usually employed to describe nonlinear aero-elastic effect. For the sake of evaluating the across-wind response of tal...
Chapter
Stahl ist prädestiniert für schlanke, weitgespannte Tragwerke. An diesen zeigen sich mitunter windinduzierte Schwingungsphänomene, u. a. infolge der stahlbautypisch niedrigen Tragwerksdämpfung. Ob sich aus Schwingungen Ermüdungsschäden einstellen oder aeroelastische Instabilitäten sogar zum Gewaltbruch führen können, ist als Nachweisaufgabe der Bau...
Article
Full-text available
The paper investigates the negative aerodynamic damping of circular cylinders in vortex-induced vibrations and compares the results of two different types of wind tunnel experiments. Firstly, forced-vibration wind tunnel tests on a rigid sectional model allow measuring the aerodynamic damping directly from the experiments. This is because the aerod...
Chapter
During the last 2 decades, new code generations have been introduced which incorporate the achieved scientific and technological state of the art that has been proven its usefulness in practical application. The Eurocodes and the CICIND model codes are examples of this development. The Eurocode applies a modified gust response factor to model in-li...
Chapter
The paper presents free-vibration wind tunnel tests performed at WIST Boundary Layer Wind Tunnel at Ruhr-Universität Bochum (Germany) on a 3D aeroelastic cylindrical model with circular cross-section. The aim of the tests is to validate a model extension to the original spectral method developed by Vickery & Basu, able to calculate the maximum osci...
Chapter
This paper presents the results of numerical investigation of the aeroelastic characteristics of an aged bridge deck. The study is developed on the hand of the Rhein-crossing bridge in Leverkusen (Germany), which is undergoing major investigations and will be likely demolished after 53 years of service. Static coefficients and instationary flutter...
Article
The paper addresses the modelling of aeroelastic forces in vortex-induced vibrations (VIV) and aims to provide a suitable model to predict cross-wind oscillations of circular structures. The Van der Pol and Rayleigh oscillators – non-linear physical systems, which attain limit cycles under self-induced vibrations – are often applied in literature t...
Article
The fluid-structure interaction in vortex-induced vibrations of circular structures is modelled as a non-linear damping force. The Van der Pol and Rayleigh oscillators are classic examples of physical systems, which attain a limit cycle under self-induced vibrations. Their application for the case of vortex-induced vibrations has a theoretical just...
Conference Paper
The analysis of the complex flow around circular cylindrical structures such as chimneys is of significant importance for the design of the structure. Special attention needs to be paid to the aerodynamic forces impacting the structure in the across-wind direction due to vortex induced vibrations. Here, the aeroelastic interaction between the fluid...
Article
Bistable flows around circular cylinders typically occur in the critical range of the Reynolds number (Re), due to the formation of a laminar separation bubble and its subsequent collapse on one side of the cylinder only. In turbulent flows, as well as on a rough cylinder at slightly higher Re, bistable flows tend to disappear. However, this paper...
Article
Full-text available
The Solar Updraft Power Plant technology addresses a very challenging idea of combining two kinds of renewable energy: wind and solar. The working principle is simple: a Solar Updraft Power Plant (SUPP) consists of a collector area to heat the air due to the wide-banded ultra-violet solar radiation, the high-rise solar tower to updraft the heated a...
Article
The bistable flow condition around a single circular cylinders is a well-known fluid dynamic phenomenon in the critical range of Re. It is sensitive not only to small variations of the Reynolds number, but also to turbulence of the incoming flow and to surface roughness of the cylinder. Bistable flows are also common for side-by-side cylinders, dep...
Article
Full-text available
The structure of Solar Updraft Towers is basically a circular cylinder, which may turn into a hyperboloid at lower levels in order apply benefits of shape strengthening. The height of the tower is up to 1.5 km and it is usually designed as a thin reinforced concrete shell. The wind action is the main natural hazard, which plays a decisive role for...
Article
Full-text available
Solar Updraft Towers - giga-towers of 1 km in height or even more in Solar Updraft Power Plants (SUPPs) - were first introduced at the last EACWE in 2009 (Niemann et al., 2009). Since then, an extensive wind tunnel investigation has been performed at WiSt laboratory at Ruhr-University Bochum and at Criaciv laboratory (University of Florence). On th...
Article
Renewable and sustainable energy sources are nowadays considered to be a key element for sustainable development of the worldwide economy. The Solar Updraft Power Plant technology addresses a very challenging, not yet exploited, idea of combining two kinds of renewable energy: wind and solar. The basic idea is the conversion of solar radiation into...
Article
Full-text available
Solar updraft power generation has first been proposed in 1903 by the Spanish engineer I. Cabanyes, followed by a description by the German scientist [Günther 1931]. Starting in 1982, a team with the German civil engineer J. Schlaich constructed a prototype solar udraft power plant (SUPP) in Manzanares, Spain, with a 200 m high solar chimney (SC) a...

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