Alessio Tosini, Enrico Cardile, Giovanni Lombardi, Marco Maganzi
2014
Cubit, Ferrari, Università di Pisa
Abstract
The experimental data corrections on automotive wind tunnel tests usually benefit of pre-test corrections methodology, which can break down working time. This methodology is based on the use of CFD simulations and yields a global correction term, sum of different contributions. It is interesting to analyze such contributions and their possible dependencies by the involved parameters, in order to have a better comprehension of the phenomenon.
In the present paper, the main purpose is to describe, with the support of a CFD analysis, the influence of the wind tunnel walls, supports and Reynolds number effects, to the global correction factor. A high performances car was taken as reference and RANS equations were used as fluid dynamic model. The CFD methodology and its validation, through a comparison with experimental data, are preliminarily presented. Afterward, the contributions to the correction term are shown and discussed. Finally, is evaluated their effect on different elements of the car. The car was split in body, wheels, underbody, radiators, rear wing and internal volumes.
Conference/Journal: ATA, Vol.67, N. 3-4, 2014
Authors: G. Lombardi, A. Tosini, E. Cardile, D. Zinelli
Enrico Cardile, Federico Cartoni, Giovanni Lombardi, Marco Maganzi
2014
Cubit, Ferrari, Università di Pisa
Abstract
The use of Computational Fluid Dynamics (CFD) provides an effective approach for the qualitative analysis of exhaust gas trajectories in high-performance vehicles under transient driving conditions. Complex flow interactions occurring during acceleration and braking phases require advanced numerical models capable of capturing unsteady effects on realistic geometries.
A CFD workflow based on automated mesh generation, unsteady simulations, and particle tracking techniques enables the investigation of exhaust plume behavior and its interaction with the vehicle underbody. The adoption of an Eulerian-Discrete Phase Model allows a reliable representation of exhaust dispersion while maintaining a balance between accuracy and computational cost, in line with industrial time constraints.
Large-scale simulations performed on HPC architectures support detailed time-dependent analyses using experimentally derived boundary conditions. The results provide valuable qualitative insight into critical flow regions potentially affecting cockpit comfort, supporting targeted experimental testing and local design modifications.
Conference/Journal: ANSYS User Group Meeting, Milano (IT)
When designing passenger cars, HVAC (Heating, Ventilation, Air Conditioning) plays an important role to the overall vehicle design process in order to satisfy thermal comfort criteria for occupants while reducing energy consumption required. In this context, a Ferrari car is analyzed with Computational Fluid Dynamics (CFD) methods to improve the internal flow inside the cockpit.
In the work detailed here the toolbox for HVAC applications available in the open source CFD software HELYX was employed. The HVAC module exploits an improved internal radiation model, a solar radiation module, support for humidity modelling, functionality to assess human comfort by parameters like PMV, PPD, DR, etc.
Enrico Cardile, Ferdinando Cannizzo, Giovanni Lombardi, Marco Maganzi
2010
Cubit, Ferrari, Università di Pisa
Abstract
Un'analisi aerodinamica che consideri gli effetti di tutti i parametri potrebbe sembrare difficile. Nell'analisi tramite ottimizzazione numerica un codice aerodinamico è accoppiato ad una routine di ottimizzazione per gestire automaticamente i valori delle variabili di progetto, con l'obiettivo di minimizzare una funzione obiettivo assegnata. Questo approccio è estremamente flessibile ed in grado di rispondere ad esigenze multidisciplinari.
Il progetto ha dimostrato l'applicabilità delle procedure di ottimizzazione nel contesto del settore automobilistico, utilizzando un codice CFD per l'aerodinamica. L'integrazione dell'ottimizzazione aerodinamica in fase di progettazione permette ai progettisti di interagire velocemente con gli altri gruppi. Diventa possibile cercare soluzioni che garantiscano le prestazioni cercate, che non influenzino negativamente lo stile dell'auto, e che al contempo diano un elevato grado di efficienza e sicurezza.
Enrico Cardile, Ferdinando Cannizzo, Giovanni Lombardi, Marco Maganzi
2010
Cubit, Ferrari, Università di Pisa
Abstract
Il comfort termico in abitacolo rappresenta un aspetto sempre più rilevante nella progettazione automobilistica ad alte prestazioni, risultando dall'interazione complessa tra fenomeni termo-fluidodinamici e percezioni fisiologiche soggettive.
Viene presentata una procedura integrata per la valutazione del comfort termico basata su simulazioni CFD, finalizzata alla definizione di indici quantitativi rappresentativi delle condizioni ambientali interne al veicolo. L'approccio combina l'analisi del campo di velocità, temperatura, umidità e irraggiamento con modelli di bilancio termico del corpo umano, introducendo un indice globale di comfort ottenuto dalla ponderazione di contributi locali legati a equilibrio termico, raffiche, gradienti verticali e laterali di temperatura.
Le simulazioni includono flussi freddi e caldi, meccanismi di conduzione, convezione e irraggiamento solare, su geometrie realistiche di abitacolo. La procedura è validata mediante prove sperimentali in galleria climatica e test soggettivi, mostrando una buona correlazione tra risultati numerici e dati sperimentali.
Enrico Cardile, Ferdinando Cannizzo, Giovanni Lombardi, Marco Maganzi
2008
Cubit, Ferrari, Università di Pisa
Abstract
In the initial phase of a car project, difficulties arise from the high number of parameters involved. A systematic aerodynamic analysis taking into account the effects of all these parameters appears to be difficult, given the complexity related to both aerodynamic load evaluation and the assessment of general requirements of the car. In the analysis through numerical optimization, an aerodynamic code is coupled in a loop with an optimization routine, to automatically manage the values of the design variables, with the aim of minimizing a given objective function. This approach is extremely flexible, and capable of meeting multi-disciplinary requirements. Therefore, in the past, it was developed an advanced, integrated design and development environment for optimizing car aerodynamics, under certain geometrical and physical constraints imposed by the designer. A potential flow code was used initially; obviously, the capabilities of this model are restricted. The important increases in both the CFD algorithms and computing capabilities, suggested the possibility to use RANS solver in the optimisation procedure. Therefore, an activity to insert in the procedure a CFD code (FLUENT) was carried out. The process is driven by the code ModeFrontier, and it can now be considered a standard tool in aerodynamic design. In this paper the general scheme of the procedure is described, and an example of the capability to improve the aerodynamic characteristics of a high performance car is presented. By using this approach, increases in the results are obtained both in the initial phase of the project, the definition of the car shape, and in the final phase, in order to optimize the details.
Authors: G. Lombardi, S. Vannucci, F. Cannizzo, E. Cardile
Conference/Journal: 7th MIRA International Vehicle Aerodynamics Conference, England
A flow discharge in the underbody car surface, usually necessary for the internal flow systems, represents a critical aspect. The effects of different shape of the discharge surfaces, both experimentally and numerically, are analysed. For all the considered aerodynamic quantities (drag, vertical load, balance) a importance of the exhaust geometry is evident. Furthermore, for some configurations, sensitivity to both the attitude and ride height is present. The high differences in the aerodynamic coefficients are essentially related to the separation of the flow, significantly different for the considered geometries, that occurs downstream the air intake exhaust.
Authors: Giovanni Lombardi, Enrico Cardile, Luca Caldirola, Stefano Carmassi
Conference/Journal: 5th MIRA International Vehicle Aerodynamics Conference, Warwick (GB)
