In the present paper a coupled thermal and a aerodynamic design process is investigated. The thermal simulation accounts for all types of heat transfer, as there is: heat conduction, heat convection and heat radiation. The aerodynamic simulation relies on a highly sophisticated turbulence model and delivers both aerodynamic forces and heat transfer coefficients. The time scales of the two simulations are too different for a fully interactively coupled simulation To overcome this issue, an iteratively coupled workflow is proposed: The process starts with a segregated CFD simulation, were the surface temperature is a first guess. The resulting HTC is averaged in time and transferred to the transient thermal simulation, were a valid surface temperature distribution is calculated. In a second fluid simulation, the heat transfer coefficient is updated. With the last thermal simulation the questioned thermal values can be calculated. The process is validated with a simplified block test case In the second part of the paper, a broad validation basis for future simulations is presented. An AUDI A7 Sportback serves as test carrier. Under investigation is a generic electric motor assembled to the rear axle carrier The effect of different modifications on cooling curves is investigated. Cooling fins on the lower side of the electric motor can improve the HTC by 10-20%, whereas the investigated cooling flow guide vane barely improves the heat transfer. The main influence is from the flow through the underhood compartment of the car. Closing of the grill can improve heat transfer at the rear axle up to 28 5%. The application of the iteratively coupled simulation process to the production car test case is considered as the next natural step.
Approach to an iteratively coupled thermal and aerodynamic design process for production cars
2014
10 Seiten, Bilder, Tabellen, 16 Quellen
Conference paper
English
Thermosimulation , Entwurfstechnik , Wärmeleitung , Wärmekonvektion , Wärmestrahlung , Kraftübertragung , CFD-Simulation , Hinterachse , Oberflächentemperatur , Zeitquerschnitt , Wärmeübergangskoeffizient , elektrischer Motor , Aerodynamik , Wärmeübertragung , Kühlmittelfluss , Durchströmung , Simulationsverfahren
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