Detailed 3D Rotor-Stator Interaction in Automotive Engine Cooling Fan Systems

In order to address the interaction of the automotive engine cooling fan with its system environment, the unsteady interaction of the fan blades with its support struts or stator vanes is presently studied. The resulting unsteady sources are consequently used to predict the tonal noise of such systems. Preliminary detailed 2D unsteady simulations at a given mean radius have helped testing the necessary numerical spatial and time parameters. A newly developed acoustic post-processing code RSF based on the Acoustical Analogy for both Rotor and Stator blades in the Frequency domain, has then been used to compute the fan system tones. An initial coarse 3D simulation has stressed the crucial role of the spatial resolution and had motivated the consequent refined simulation of the complete reference fan system, for which the main features and preliminary results are highlighted here. A first comparison with experimental noise data on a similar system also suggests a partial contribution of this mechanism to the spectral tones.