During the development of a sports car, in which we were involved, an even more powerful engine was to be installed.

The problem with the first prototypes was not driving. Here, there is usually sufficient airflow at higher speeds to supply all relevant components such as the engine, brake radiator and above all the hot exhaust system with sufficient cooling air.

The problems occurred while drinking coffee at the rest stop.
The vehicle was parked properly, certain plastic parts above the engine now felt the vehicle reheating, became too hot, dripped on the engine, ignited and a prototype costing several million disintegrated into smoke and pleasure.

This was the beginning for us to specifically observe the post-heating properties of vehicles via CFD simulations and to develop suitable and efficient calculation methods for this purpose.

In the beginning the CFD models, which are already complete vehicle models, were relatively simple. The engine was a massive block that had an initial temperature and cooled down via radiation and free convection. The engine compartment was only shown in a simplified form. Later more and more details were added, not only the standing but also the moving vehicle was considered and the models became more and more extensive.

Even if you may not believe it, even a car can run out of air and the individual development departments (for brakes, engine, drive train, cooling circuit) fight over what cooling air is needed.

Thermal management is the question of the level of temperature that can occur at different points in time and environmental conditions on different components and whether this is still permissible.

And it is the question of what can be done if the temperature is too high.

Here, detailed considerations are of only limited help.

Nowadays, the entire vehicle is entered into the computer. In addition to the flow via CFD, temperatures and heat transfer mechanisms such as radiation, convection and heat conduction have to be considered.

The limiting factor for the model size is often the radiation. However, Moor’s Law strikes mercilessly here too and what was unthinkable years ago is already state of the art today.

We use different software pairings for CFD calculations and temperature calculations. Flow and temperature are solved transiently in co-simulations.

Will these issues become irrelevant when it comes to electromobility and fuel cells? On the contrary!

Here the temperature control of the stacks and the batteries is even more important, temperature differences lead to losses up to overheating, short circuit and fire hazard. And extinguishing a fire under high voltage is anything but fun.

Everyone who has ever peed against an electric fence as a boy knows this from his own experience. Or am I alone in this?

Thermal management with CFD is the ultimate discipline.

Work together with us as a very experienced partner. Send us an e-mail and we will be happy to advise you without obligation in a personal meeting.

I look forward to meeting you.

Your Stefan Merkle

PS: Also chainsaws, lawnmowers, electric motors and everything else in the garage can get too hot … even machine tools, tanks and airplanes. But that is another story.