1,721,189 research outputs found
Parametric Analysis of the Acoustic Response of the VEGA Launcher Fairing in Critical Acoustic Phases”. Relazione finale per la Convenzione di ricerca tra Dipartimento e Avio S.p.A., Luglio 2004.
No full textParametric Analysis of the Acoustic Response of the VEGA Launcher Fairing in Critical Acoustic Phases”. Relazione finale per la Convenzione di ricerca tra Dipartimento e Avio S.p.A., Luglio 2004
Finite-State Aerodynamic Modelling for Gust Load Alleviation of Wing-Tail Configurations
No full textMultiblade Reduced-Order Aerodynamics for State-Space Aeroelastic Modeling of Rotors
No full textReduced-order aerodynamic models are tools that may be conveniently applied in a wide range of research and design applications in the aeronautical and mechanical fields. This paper presents a methodology for the identification of a Reduced-Order Model (ROM) describing the linearized unsteady aerodynamics of helicopter rotors in arbitrary steady flight, that is particularly suited for the derivation of the state-space perturbation aeroelastic operators and hence useful for stability analysis and aeroservoelastic applications. It is defined in terms of multiblade coordinates and yields a (finite-state) constant-coefficient, linear, differential form relating them to the corresponding multiblade aerodynamic loads.
This approach requires the prediction of a set of harmonic perturbation responses by an aerodynamic solver. The accuracy of the identified ROM in describing unsteady aerodynamics phenomena is strictly connected to that of the
aerodynamic solver. Complex aerodynamic effects (like wake roll up, wake-blade interactions) are included in the ROM if they are taken into account in evaluating the harmonic responses.
Numerical results concerning a flap-lag helicopter rotor in forward flight are presented. These examine the accuracy the aerodynamic ROM introduced both in terms of aerodynamic loads predictions
and in terms of aeroelastic stability analysis. An aeroservoelastic application is also included in order to demonstrate the suitability of the ROM proposed for the design of controllers
A Multiblade Aerodynamic Reduced-Order Model for Aeroelastic Analysis of Helicopter Rotors in Forward Flight
No full textTime-Dependent Coefficient Reduced-Order Model for Unsteady Aerodynamics of Proprotors
No full textThis work presents a methodology for the identification of a periodic-coefficient reduced-order model (ROM) for the prediction of perturbation aerodynamic loads on tiltrotor propellers in cruise flight. Although the result is a periodic-coefficient model, the process requires only frequency-domain aerodynamic solutions. Assuming the unperturbed proprotor in axial flow, the matrix that collects the aerodynamic transfer functions between blade perturbative boundary conditions and generalized aerodynamic forces is first derived. Then its rational matrix approximation, followed by combination with the equations describing the wing/pylon/proprotor kinetic coupling, yields the aerodynamic ROM. This ROM is expressed in terms of a set of linear equations that relate the time
evolution of the aerodynamic loads acting on the proprotor blades to wing/pylon and deformable-blade degrees
of freedom. Numerical results concerning a three-bladed proprotor connected to a bending and twisting wing will
show that the unsteady aerodynamic loads predicted by the proposed ROM are in excellent agreement with those
obtained through direct time-marching aerodynamic solutions
Elementi di meccanica razionale
No full textQuesto libro presenta la trattazione teorica dei temi fondamentali della Meccanica Razionale. Gli argomenti discussi, la loro sequenza, la simbologia utilizzata e la modalità di sviluppo della teoria attraverso cui si giunge alla definizione dei modelli matematici utili alla soluzione dei problemi della Meccanica Razionale sono quelli ritenuti dagli autori più idonei per allievi ingegneri che frequentano un corso di laurea triennale di indirizzo industriale. Partendo dai richiami sull’Algebra vettoriale e la Dinamica del punto materiale, il testo prosegue con lo studio dei Sistemi particellari che risulta essere anche propedeutico per gli argomenti trattati nei successivi capitoli. Quindi si esaminano i temi della Cinematica del corpo rigido, per poi arrivare allo studio dei Moti relativi per l’introduzione dei sistemi di riferimento non inerziali, e allo sviluppo dei modelli matematici per la Dinamica del corpo rigido. Un capitolo viene dedicato agli elementi della Meccanica lagrangiana
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