Improving Fan Conception to Get the Expected Performance

Keep the engine of vehicles working in optimum temperature conditions is one of the main functions of cooling systems. It helps to extend the engine lifetime and to decrease fuel consumption, then contributing to reduce the CO2 emissions.

As part of the engine cooling system, the fan system is used to force air through the radiator, increasing the dissipation of heat. So, the final thermal performance is closely linked to the fan aerodynamic efficiency.

Unfortunately, even if fans are made of injected reinforced plastic, they deform under rotation, degrading the efficiency. This issue has led us to develop a methodology able to provide a pre-deformed design, so that the blades shape are as expected when the fan is turning.

Once the geometry which leads to the expected performance is defined, the process starts from a rheology simulation in order to calculate fibers orientation. This result is used to determine the mechanical stiffness anisotropy needed for further structural simulations.

A fluid simulation is also performed, aiming to estimate the aerodynamic loads. These values are then combined to the inertial load to get blade deformation through a structural simulation.

This last output is used to build a counter-deformed mesh, obtained by inversing the displacements, and then used as input in a new cycle of simulations.
The approach includes a comparison between the deformed shape and the recommended one. If differences are detected, they are integrated to the counter-deformed concept, until the gap falls into a predefined tolerance.

 

The Author

Rodrigo BENEVIDES
Simulation Expert & Team Leader
Valeo Powertrain Thermal Systems - La Verrière