Carello, M., Andrea, S., Airale, A., and Ferraris, A., "Design the City Vehicle XAM using CFD Analysis," SAE Technical Paper 2015-01-1533, 2015, doi:10.4271/2015-01-1533.
XAM is a two-seat city vehicle prototype developed at the Politecnico di Torino, equipped with a hybrid propulsion system to obtain low consumptions and reduced environmental impact.The design of this vehicle was guided by the requirements of weight reduction and aerodynamic optimization of the body, aimed at obtaining a reduction of resistance while guarantying roominess. The basic shape of the vehicle corresponding to the requirements of style, ergonomics and structure were deeply studied through CFD simulation in order to assess its aerodynamic performance (considering the vehicle as a whole or the influence of the various details and of their changes separately). The most critical areas of the body (underfloor, tail, spoiler, mirrors, A-pillar) were analyzed creating dedicated refinement volumes.The CFD analysis confirmed that the shape of the simplified model, having been created in compliance with the best practices of automotive literature, had a good aerodynamic performance, synthesized by a low Cx.The development of the aerodynamics of XAM has followed the workflow: geometry modeling, simulation, analysis of results, and finally geometry changes. This study represents an iterative process very challenging since the implementation of each change in the surface model has required a relatively long time (with no automation in the process of generation of surfaces). This approach has proven itself very convenient from the design point of view as it has allowed estimating qualitatively how the different components might have been modified to achieve the best performance already in the design phase of a new car model.