Analysis of flow phenomena on an acoustic roller dynamometer in order to analyse the flow through the engine compartment and on the underbody for thermal applications

摘要

Testing times in climatic wind tunnels are rare and expensive. In the development process of vehicles virtual testing and road tests are essential to reduce development costs. MAGNA STEYR runs a four wheel drive acoustic roller dynamometer with wind simulation up to 135 km/h which could also be used for thermal testing. It is definitely not the goal to have the right c{sub}P distribution on the upper side of the vehicle or the right drag coefficient as this would not be possible with the dimensions of the nozzle. The nozzle from the wind simulation is rather small and thus the flow is not the same as in an climatic wind tunnel. For thermal applications especially the flow towards the radiator, through the engine compartment and on the underbody (up to the B-column) are of special interest. The current work focuses on the differences in the flow when looking on the roller dynamometer compared to an climatic wind tunnel and road tests focussing on the flow towards the radiator, through the engine compartment and on the underbody (up to B-column). The differences are shown on a thermal model of a full vehicle. This model is run under typical testing conditions (e.g. 35 km/h hill with trailer). To perform these simulations a conventional CFD is used. Three environmental testing conditions are simulated and compared to each other. These are the acoustic roller dynamometer, the climatic wind tunnel and the road simulation. The aim is to show whether the acoustic roller dynamometer can be used for thermal investigations and where the limits of the wind simulation are.