Modelling of door cavities and simulations to assess ow properties in door cavities for dirt/dust applications

Examensarbete för masterexamen
Kukreja, Sagar Mahesh
In the automotive industry, where lead times are long and prototypes expensive, simulation driven designs play a vital role to reduce the overall cost and development time. Various tools utilizing Computational Fluid Dynamics (CFD) are used to e.g. evaluate the aerodynamic performance of vehicles. Firstly, the automotive industry is in the midst of a switch from combustion to electrified vehicles, hence it is essential to improve vehicle efficiency in order to increase the range of the battery. Secondly, modern vehicles are equipped with multiple cameras and sensors connected to driving aid and safety systems. For these systems to function well, the regions where cameras and sensors are mounted cannot be contaminated by e.g. snow or dust. Finally, preventing dirt/dust intrusion to the door-cavities of a car is desirable, as dirt/dust present in this region will likely cause soiling of the occupants when exiting/entering the vehicle. The Contamination and Core CFD department is responsible for the experimental and virtual assessment of contamination performance at Volvo Car. In prior tests the in-cavity air ow at the tailgate cavities have been evaluated. However, the cavities at the doors were not analysed for dirt/dust intrusions. The objectives of this thesis is to use previous knowledge and data on how to predict flow fields in cavities, and from that formulate a multiphase approach to also include dust/dirt distribution in the simulations by means of experiments and CFD. The vehicle geometry used for experimentation and CFD analysis is a Volvo V90 D4 AWD. The geometry to capture the cavities was prepared using ANSA and the following simulations were conducted in StarCCM+. The vehicle was driven on gravel roads to analyse, compare and validate dust patterns in the door cavities. The conclusions from the thesis is that it is possible to resolve the door cavities and subsequently simulate the in-cavity ow pattern in these cavities using CFD. In general, the dust particle are observed to enter the cavities at two major regions. First, at cavities between the fender, the front door and the sill moulding. Second, at cavities between the front door, rear door and the sill moulding.
Multiphase modelling, aerodynamics, in-cavity flow,, dirt/dust intrusions, door cavities, passenger vehicles, CFD simulations, StarCCM+, ANSA, contamination, self-contamination
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