Experimental analysis of the sound radiated by an automotive cooling module working at different operational conditions

Abstract

An automotive cooling module working at three different operating conditions is investigated using a microphone array method. Experiments on an open rotor and on a full module configurations were conducted in the ALCOVES anechoic chamber of the von Karman Institute for Fluid Dynamics, Belgium. The acoustic data are post-processed using the ROtating Source Identifier algorithm. As first step, the method was applied for the fan-alone configuration at the nominal operating point. The sound maps of one-third octave band are discussed with respect to the minimum resolving frequency emerging by the Rayleigh criterion. Integrated spectra of the whole beamforming maps are used to validate the method whereas acoustic characteristics of the fan are identified by evaluating integrated spectra of each blade separately. Subsequently, the ROSI method was applied to both configurations, demonstrating the acoustic transparency of the automotive heat exchanger. Depending on the adjusted mass flow rate, sound sources are located on the leading or trailing edges of the fan blades. To complement the analysis, sound directivity measurements have been carried out in the anechoic wind tunnel at the University of Sherbrooke, Canada, on an another sample of the same engine cooling module.