1,246 research outputs found
Integrated Aeroservoelastic Analysis of Induced Strain Rotor Blades
No full textThis paper presents an application of an original formulation for the characterization of generally anisotropic, non-homogeneous beam sections including induced-strain devices (in this case piezo-electric patches) to the aeroservoelastic analysis and optimization of actively twisted helicopter rotor blades. The induced-strain inclusions can have arbitrary shape and orthotropy. The beam section characterization is based on a semi-analytical approach to the analysis of the beam, where the section is modeled as a 2-D FE model. The linear and angular strains of the beam, the free warping of the section and the electric potential are solved in terms of unit internal forces, moments and electric charge density on the electrodes under appropriate boundary conditions to provide the elastic and electro-static solution of the compliance problem. This solution yields the 6 × 6 generalized elastic and inertia properties, the 6 × N generalized piezo-electric properties and the N × N dielectric properties of a piezo-electric beam section characterized by N independent piezo-electric patches. These properties, and detailed information about the strain and stress state inside the beam section for each span-wise location are used to synthesize noteworthy geometric, mechanical, aeroelastic and piezo-electric properties to be used in the definition of the objective function and the constraints of an aeroservoelastic optimization problem. The piezo-electric blade section characterization is detailed; the optimization procedure is illustrated, and relevant results are presented and discussed in view of indications arising from simplified models based on the monocoque theory
A Novel Scheme for Two-Dimensional Compressible Flow on Moving Meshes with Large Deformations
No full textCompressible Fluid-Flow ALE Formulation on Changing Topology Meshes for Aeroelastic Simulations
No full textThe analysis of unsteady fluid flows on moving domains is a very complex task, that may be often tackled using domain remeshing techniques. In the present paper a novel mesh movement strategy is presented. It is based on the blending of simple local edge-swapping with mesh deformation by means of the elastic analogy. To deal with mesh topology changes an extension of the classical Arbitary Lagrangian-Eulerian formulation of the fluid flow equations is developed. In this way the use of interpolations of fluid fields between old and new grid is avoided. Furthermore, this extension allows the easy implementation of high order time integration schemes. Preliminary two dimensional numerical simulations are presented to demonstrate the correctness of the present approach. They shows how this approach guarantees a high quality of the grid without resorting to remeshing, resulting in a very efficient solver useful for the analysis of Fluid-Structure Interaction problems, even for the cases which requires large mesh deformations or changes in the domain topology
Correction to: When terminology hinders research: the colloquialisms of transitions of control in automated driving (Cognition, Technology & Work, (2022), 10.1007/s10111-022-00705-3)
No full textIn the original article, author affiliation published with error. The correct affiliations are: Davide Maggi—Institute for Transport Studies, Leeds, UK. Richard Romano—Institute for Transport Studies, Leeds, UK. Oliver Carsten—Institute for Transport Studies, Leeds, UK. Joost C. F. De Winter—Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands. The original article has been corrected.Human-Robot Interactio
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
Starchitecture: Scenes, Actors and Spectacles in Contemporary Cities
No full textHow and why do spectacular buildings get commissioned and procured? What are their visible urban effects? What can urban planners, architects, and policymakers learn in order to engage in more successful citymaking?
In recent years, media and critical attention has been lavished on famous architects, and the contributions of their designs to the branding of cities. The post-“Bilbao effect” global landscape is one where cities compete for the highest-profile skyscrapers, cultural projects, and high-profile developments designed by star architects whom even casual readers know by first name: Frank Gehry, Bjarke Ingels, Jean Nouvel, Zaha Hadid, Norman Foster, Rem Koolhaas. Far less is known about the decision-making processes behind these projects and their subsequent urban effects.
A unique combination of urban studies and photography, Starchitecture investigates projects designed by star architects in cities including Paris, New York, Abu Dhabi, Bilbao, and the architectural microcosm of the Vitra campus in Weil am Rhein, Germany. Author Davide Ponzini and photographer Michele Nastasi seek to explain and critique a growing global condition by revealing how starchitecture has been and continues to be deployed in cities around the world. The arguments they raise are vital to understanding the urban landscapes of today, and tomorrow
Sviluppo di modelli aerodinamici di ordine ridotto per l’analisi del buzz di alettone
No full textLAUREA MAGISTRALEIl presente lavoro di tesi è stato svolto durante uno stage presso l'unità organizzativa di aerodinamica della Divisione Velivoli di Leonardo.
Obiettivo del lavoro è quello di costruire dei modelli aerodinamici ridotti che siano in grado di cogliere gli effetti dinamici, non lineari e instazionari, conseguenti ad un movimento di una superficie portante in regime transonico, a partire da un'opportuna base di simulazioni CFD.
%In queste condizioni l'isteresi del flusso provoca un ritardo della risposta aerodinamica che può avere un effetto sulla stabilità aeroelastica. Inoltre, le non linearità legate alla formazione e al movimento delle onde d'urto e alla presenza di flussi separati, possono avere un effetto significativo sulle prestazioni.
Il lavoro si concentra sull'analisi del buzz di alettone, fenomeno in cui questi effetti hanno un ruolo chiave e che può essere riprodotto attraverso la simulazione numerica solo con una loro corretta modellazione.
In una prima fase, è stato costruito, a partire da un articolo disponibile in letteratura, un modello aeroelastico semplificato della semiala del velivolo Lockheed P-80, il primo ad aver esibito il fenomeno in volo, su cui è stata effettuata un'analisi di stabilità alle piccole perturbazioni, al variare della condizione di linearizzazione dell'aerodinamica. Tale analisi si è resa necessaria per determinare la potenziale insorgenza del fenomeno sul modello in esame.
In una seconda fase, è stato costruito un modello aerodinamico ridotto e non lineare dell'alettone, che permette di ottenere il momento di cerniera conseguente ad un arbitraria storia temporale di deflessione della superficie mobile, attraverso un integrale di convoluzione. Il modello è stato validato mediante una serie di simulazioni CFD ed è stato, successivamente, accoppiato con il modello di dinamica strutturale dell'alettone per ottenere la risposta del sistema aeroelastico all'imposizione di opportune condizioni iniziali.
I risultati dell'integrazione del sistema aeroelastico sono concordi con le analisi di stabilità e con la risposta del modello CFD completo. Questo permette di concludere che il modello aerodinamico ridotto, accoppiato con il modello strutturale dell'alettone, consentono di predire sia l'insorgenza del ciclo limite, sia le sue caratteristiche di ampiezza e frequenza.
In conclusione del lavoro, viene presentata un'analisi svolta su un modello del velivolo M346, in una particolare condizione di volo supersonica, in cui sono state osservate delle oscillazioni ad alta frequenza del timone di direzione. Sono state descritte le caratteristiche del campo aerodinamico, focalizzando l'attenzione sui fenomeni instazionari che interessano la regione attorno al piano verticale, mettendo in luce le differenze fenomenologiche tra quanto osservato sul velivolo e il buzz di superficie mobile descritto in precedenza.
I risultati ottenuti dall'applicazione dei modelli sviluppati in questo lavoro sono in accordo con quanto osservato durante le prove di volo e sono utilizzabili per valutare eventuali soluzioni progettuali per attenuare il fenomeno.This thesis work has been developed within an internship at the Aerodynamics Unit of Leonardo, Aircraft Division.
The goal of the work is to build a reduced-order aerodynamics model, capable of catching dynamics, unsteady and nonlinear effects due to the movement of a lifting surface in the transonic regime, using a set of CFD simulations.
The focus is on aileron buzz, which involves these effects. Moreover, its correct numerical simulation strongly depends on a proper nonlinear unsteady aerodynamics modelling.
On a first phase, an aeroelastic model of the left half-wing of Lockheed P-80 aircraft has been produced and a small perturbations stability analysis has been performed, varying the linearizing point. This analysis showed the presence of the phenomenon on the model.
On a second phase, a nonlinear reduced-order model has been produced, which gives the hinge moment time history due to an arbitrary movement of the aileron, using a convolution integral. The model has been validated, using some full-order CFD simulations, and then coupled with the aileron structural model to obtain the response of the aeroelastic system to arbitrary initial conditions.
Results meet the stability boundaries and with the response of the full-order CFD model. We conclude that this nonlinear reduced-order aerodynamic model, coupled with the aileron structural model, is capable of predicting the limit cycle onset and its frequency and amplitude.
At the end of this work, an analysis is presented about the M346 aircraft in a supersonic flight condition. Flight tests conducted in the same conditions showed high-frequency rudder oscillations. The aerodynamics of the vertical tail has been described, focusing on unsteady phenomena around the vertical tail and pointing out the differences between these and the control surface buzz previously described. A linear model is used to reproduce the rudder oscillation and results are in good agreement with experimental tests. They can be succesfully used for the analysis of new design solution to reduce the oscillations
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