Experiments and numerical simulations of snow contamination for automotive bluff bodies
2022-01-1081
03/29/2022
- Event
- Content
- The automotive industry is in a transformation process where advanced active safety systems are developed to make it feasible with autonomous vehicles. With this development the need for sensor availability is essential since the systems depend on the sensors surrounding the vehicle. One of the challenges with sensor availability is during driving in cold weather conditions, where accumulation of snow on a sensor surface can block the sensor. In this work we studied snow surface contamination of automotive bluff bodies. Specifically, we studied the Ahmed body as well as a simplified wedge body using experiments and numerical simulations. The objective of our work was to develop a numerical method that can predict snow contamination as well as increase the knowledge of this type of surface contamination. Experiments were performed in a climatic wind tunnel using a snow cannon at -15 °C. The experiments show that the deposition rate depends strongly on the aerodynamics of the bluff bodies and snow accumulation is especially present in the aerodynamic wakes of the bodies. The numerical method consists of a Eulerian hybrid LES/RANS simulation, a Lagrangian particle tracking model, and a velocity dependent collision model. The collision model determines if a particle stick or bounces and was implemented based on JKR contact theory for adhesive-elastic particles. The numerical simulations predict that particles generally bounce on initial collision and multiple collisions are needed for a particle to adhere to a wall. The same observation is made in the experiments, where many particles are seen to bounce away from the bluff bodies and only few particles accumulate on the surfaces. Our results also show that the unsteady velocity fluctuations are an essential part of the transportation of particles.
- Citation
- Eidevåg, T., Eng, M., Kallin, D., Casselgren, J. et al., "Experiments and numerical simulations of snow contamination for automotive bluff bodies," SAE Technical Paper 2022-01-1081, 2022, .