Cooling Airflow Simulation for Passenger Cars using Detailed Underhood Geometry

Air flow in the underhood area is the primary source of engine cooling. A quick look at the vehicle underhood reveals exceptionally complex geometry. In addition to the engine, there are fans, radiator, condenser, other heat exchangers and components. The air flow needs to have adequate access to all relevant parts that require cooling. Due to complex geometry, the task to ensure sufficient air cooling is not a simple one. The air flow entering from the front grille is affected by many components on its path through the underhood. Even small geometry details affect the flow direction and can easily cause recirculation regions which reduce the cooling efficiency. Therefore, air cooling flow analysis requires detailed treatment of the underhood geometry and at the same time accurate air flow modeling. Recent advances in the lattice-Boltzmann equation (LBE) modeling are allowing both. Presented is analysis of air-cooling flow over a passenger vehicle, Land Rover LR3, that includes detailed external and underhood geometry. Simulations were performed using PowerFLOW, an LBE based flow solver. Shown are flow structures that form at 95 km/h and their effect on the overall cooling flow rate and coolant temperatures in the heat exchangers.