1,720,993 research outputs found
Analisi CFD in autoclave di sezioni di fusoliera 46-9 del velivolo B787
No full textReport of Depart. of Aerospace Eng. of Pisa, DDIA 2009-23, Sept. 200
Flow around a wing: improvement of physical comprehension by using a DES model.
No full textThe flow around a wing is usually well represented by a RANS simulation in cruise conditions, because the zones with flow separations are absent or very small. But, as the angle of attack increases, because of the request of higher lift values, the separated flow zones become important, and the flow is more complex.
In these conditions, a RANS approach, also with an unsteady solution, could be not satisfactory. Therefore, we decided to investigate this aspect, by comparing the results of an unsteady RANS solution with a DES solution.
In the paper, the setting of both cases are described, as well as the comparison in terms of global coefficients, local distributions and field vorticity distributions.
The results show that, at low angle of attack, not significant differences between the RANS and DES solutions occur. On the contrary, at higher angles of attack, the flow highlights a different behaviour (some results are shown in the following figures), with the DES approach that seems to give a more realistic representation of the flow itself.
It is important to note that the difference between RANS and DES results is so considerable that also the lift, drag and pitching moment are significantly changed.
Finally, it is possible conclude that the use of a DES approach appears an improvement to evaluate the aerodynamics characteristics of a wing close to the stall conditions, a relevant problem for the aerodynamics design of an airplane
Caratterizzazione delle prestazioni aerodinamiche del velivolo Selex Galileo Falco Evo
No full textDDIA 2011-1
L’uso della Fluidodinamica Numerica nel Progetto Aerodinamico di Auto ad Alte Prestazioni
No full textGli aspetti aerodinamici rappresentano tradizionalmente una parte importante nel progetto di una vettura ad alte prestazioni; essi sono comunque molto legati a quelli stilistici, oltre a dover rispettare le esigenze derivanti dagli aspetti tecnici/costruttivi.
Nel corso degli anni vi è stato un notevole incremento delle prestazioni delle vetture. Questo, insieme ai requisiti di sicurezza e di confort sempre più stringenti, ha portato l’aerodinamica ad assumere un ruolo sempre più centrale nella progettazione di queste auto; ciò soprattutto per ottenere elevati carichi verticali e una loro corretta distribuzione tra asse anteriore e asse posteriore.
Nella prima fase del progetto lo stilista produce un gran numero di proposte, in tempi relativamente brevi. Ciò è incompatibile con un’analisi delle prestazioni aerodinamiche fatta con il classico strumento della galleria del vento, per la quale i tempi di risposta sono troppo lunghi (nell’ordine dei mesi), e questo ha portato al fatto che gli aspetti aerodinamici influenzassero la forma solo in una fase successiva del progetto, con dei margini d’intervento ovviamente molto più limitati
Analisi CFD in autoclave di sezioni di fusoliera 46-8 nuova generazione del velivolo B787
No full textReport of Depart. of Aerospace Eng. of Pisa, DDIA 2009-16, Sept. 2009
Analisi calda del flusso in autoclave
No full textReport of Depart. of Aerospace Eng. of Pisa, DDIA 2009-22, Sept. 2009
Centrifugal compressors Diffuser Rotating Stall Deep Insight
No full textIn this work the numerical analysis of a small flow coefficient stage vaneless diffuser is described. The main purpose of this analysis is to go inside the rotating stall physics with particular attention to the onset of the rotating cells and their properties. The diffuser aspect ratio (width divided radial extension) is low (0.03) and the effect of the wall (hub and shroud boundary layers) cannot be neglected. For this reason the model is a 3D model including the hub, the shroud walls and the downstream 180° cross- over bend. The numerical analysis has been carried out using an incompressible, viscous, unsteady commercial solver. Radial and tangential typical velocity profiles as produced by a hypotetical upstream impeller have been applied as boundary conditions and they have been changed in time to simulate the actual throttling valve closure as it is done during a test. Under these circumstances a rotating phenomenon is found to exist similar to what is found experimentally on similar geometries. The instability starts as a complex 3D flow involving both hub-to-shroud flow pulsations as well as radial non-uniformities and it stabilizes in the form of four rotating cells
Attività di supporto per lo sviluppo aerodinamico della configurazione MARTE – Verifica degli Accoppiamenti Aerodinamici e Modifiche alla Geometria delle Ali e del Mangia Strato Limite.
No full textAttività di ottimizzazione di superfici alari
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