Experimental and numerical investigations of underhood flow for vehicle thermal management
Computational Fluid Dynamics (CFD) is an important tool for the investigation of the underhood flow, since it gives the possibility to look at the flow field even in areas where measurement equipment cannot reach. In the first part of this work, the focus is on the simulation of the axial cooling fan. Different methods to simulate an axial cooling fan were compared to each other and to experimental data that was acquired using Laser-Doppler-Anemometry. The commonly used Multiple Reference Frame approach was shown not to be suitable for investigating underhood flow, as the stationary blades leave an imprint on the wake flow. In addition, inhomogeneous temperature distributions experienced an unphysical rotation due to the switch in reference frame. These issues do not occur with the Rigid Body Motion approach, and the simulation results compared well to the measurements.
In the second part of this project, it was investigated how the flow downstream of a fan is affected by different components placed up- and downstream. A simplified underhood rig was designed and constructed to provide a controlled, vehicle-like environment for the measurements and simulations. Two front designs, representative of a hybrid and a battery electric vehicle, were utilised and it could be shown that the upper grille opening that is missing in the battery electric vehicle configuration has a visible impact on the flow field downstream of the fan. Simulating the same configurations in CFD showed some differences to the experimental data. For a second cooling fan, the results were well matched.
Vehicle thermal management
Simplified underhood environment
Chalmers, Mekanik och maritima vetenskaper, Fordonsteknik och autonoma system
Validation of Different Fan Modelling Techniques in Computational Fluid Dynamics
Proceedings of the 21st Australasian Fluid Mechanics Conference ,; (2018)
Paper i proceeding
Evaluation of the Multiple Reference Frame Approach for the Modelling of an Axial Cooling Fan
Energies,; Vol. 12(2019)
Artikel i vetenskaplig tidskrift
Franzke, R., Sebben, S., Willeson, E., "Experimental investigation of the air flow in a simplified underhood environment"
Franzke, R., Sebben, S., Willeson, E., "Numerical investigation of the air flow in a simplified underhood environment"
Numerical simulations are an important tool for the investigation of the underhood flow since they provide insight into the flow field even in areas where measurement equipment cannot reach. In the first part of this work, the focus is on the simulation of an axial cooling fan. Different methods to simulate the axial cooling fan were compared to each other and to experimental data. It was shown that advanced models are necessary to accurately capture the flow field and the transport of flow properties through the fan region.
For the second part of the thesis, a simplified underhood rig was designed and built to provide a controlled, vehicle-like environment for physical measurements and numerical simulations. Significant changes to the flow field could be triggered by restricting the front openings or placing different blockages into the test section. It could, for example, be seen that the reduced grille opening in a battery electric car has a notable effect on the flow field behind the fan. The simulations on the same configurations showed good agreement to the measurements for one fan design, while for a second fan some deviations were noticeable.
Industriell applicerbar simuleringsmodell för hybrid- och elbilar för analys av termodynamisk status i komplett bil
Energimyndigheten (2015-011207), 2016-10-25 -- 2019-12-31.
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5052
Chalmers tekniska högskola
Vasa A, Vera Sandberg allé 8, Chalmers
Opponent: Dr. Burkhard Hupertz, Ford Motor Company, Germany