Riassunto analitico
Negli ultimi anni è cresciuta in maniera significativa l’attenzione verso i veicoli alimentati da fonti di energia differenti rispetto ai combustibili tradizionali: si è assistito a un’affermazione dei veicoli ibridi o elettrici, nonché ad una “larga” diffusione dei veicoli a energia solare.
L’attenzione verso quest’ultimo tipo di veicoli è confermata non solo dalla diffusione di queste vetture (soprattutto mezzi pubblici, anche se si stanno affermando city car e persino berline) ma anche dalla diffusione di competizioni ad esse dedicate, come la Shell eco-marathon, la Formula Sun Grand Prix o la World Solar Challenge.
Per vincere quest’ultima competizione è necessario percorrere i 3021 km che collegano Darwin con Adelaide (rispettivamente agli estremi nord e sud dell’Australia) nel minor tempo possibile, e quindi con la maggiore velocità media. Per poter fare ciò, poiché l’unica fonte di energia a cui si può attingere è l’energia solare, è fondamentale curare attentamente l’aerodinamica della vettura.
Il lavoro svolto si è quindi concentrato su una vettura partecipante a questa competizione, la World Solar Challenge: il veicolo in questione è l’Emilia4 dell’azienda bolognese “Onda Solare”.
È stata studiata l’aerodinamica della vettura a partire dall’ultimo design ottimizzato attraverso simulazioni fluidodinamiche, per riprodurne il comportamento reale in una galleria del vento fittizia. A partire dal disegno CAD è stato scelto il modello di turbolenza, i metodi numerici e le condizioni al contorno ottimali per il caso in questione. Sono quindi state realizzate molteplici mesh con software come Pointwise o Star-CCM+ quindi è stato simulato il comportamento della vettura in una galleria del vento fittizia, al fine di verificarne l’effettivo comportamento in gara. Per questo tipo di simulazioni sono stati utilizzati OpenFoam e Star-CCM+ e i casi presi in questione sono molteplici, con ruote fisse o ruote mobili […]
Dall’analisi del postprocessing sono state individuate soluzioni ottimali per rendere la vettura più competitiva, quindi sono state apportate modifiche alla geometria per ridurne il coefficiente di penetrazione, senza andare a togliere spazio all’interno della vettura.
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Abstract
In the last few years, the attention to vehicles powered by different energy sources has increased significantly compared to traditional fuels: there has been a confirmation of hybrid or electric vehicles, as well as a "wide" diffusion of solar-powered vehicles.
The attention towards this type of vehicle is confirmed not only by their diffusion (above all public transport, even if city cars and even sedans are being established) but also by the diffusion of competitions dedicated to them, such as Shell eco-marathon, the Formula Sun Grand Prix or the World Solar Challenge.
In order to win this last competition, it is necessary to cover the 3021 km connecting Darwin with Adelaide (northern and southern extremes of Australia respectively) in the shortest time, and therefore with the highest average speed. In order to do this, since the only energy source that can be tapped is solar energy, it is essential to take care of the aerodynamics of the car.
The work has therefore focused on a car which participate in this competition, the World Solar Challenge: the vehicle in question is Emilia4 of the Bologna-based team "Onda Solare".
The aerodynamics of the car was studied starting from the last design optimized through fluid dynamic simulations, to reproduce the real behaviour in a fictitious wind tunnel. Starting from the CAD model, the turbulence model, the numerical methods and the optimal boundary conditions for the case in question were chosen. Therefore, several types of mesh were created with software such as Pointwise or Star-CCM+ so the car behaviour was simulated in a fictitious wind tunnel, in order to verify its actual behaviour during the competition.
The post-processing analysis identified optimal solutions to make the car more competitive, several changes were made to the geometry in order to reduce the drag coefficient, without taking up space inside the car.
Attention towards this type of vehicle is confirmed not only by the diffusion of these vehicles (above all public transport, even if city cars and even sedans are being established) but also by the diffusion of competitions dedicated to them, such as Shell eco- marathon, the Formula Sun Grand Prix or the World Solar Challenge.
In order to win this last competition, it is necessary to cover the 3021 km connecting Darwin with Adelaide (at the northern and southern extremes of Australia respectively) in the shortest possible time, and therefore with the highest average speed. In order to do this, since the only energy source that can be tapped is solar energy, it is essential to take care of the aerodynamics of the car carefully.
The work has therefore focused on a car participating in this competition, the World Solar Challenge: the vehicle in question is Emilia4 of the Bologna-based company "Onda Solare".
The aerodynamics of the car were studied starting from the last design optimized through fluid dynamic simulations, to reproduce the real behaviour in a fictitious wind tunnel. Starting from the CAD drawing, the turbulence model, the numerical methods and the optimal boundary conditions for the case in question were chosen. Therefore, multiple meshes were created with software such as Pointwise or Star-CCM + so the car's behaviour was simulated in a fictitious wind tunnel, in order to verify its actual behaviour during the race. For this type of simulations OpenFoam and Star-CCM + have been used and the cases taken into question are multiple, with fixed wheels or mobile wheels [...]
The post processing analysis identified optimal solutions to make the car more competitive, so changes were made to the geometry to reduce the penetration coefficient, without taking up space inside the car.
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