Dissociation of noise sources foraeronautical fans

Abstract: To ensure health and hearing comfort, acoustics becomes more and more essential in the design of fans. 3D numerical calculations (mechanical, aerodynamic and magnetic) are used to ensure the compliance of fans before production test prototypes. However, numerical modelling is long and costly to the company; the use of analytical software calculations is an alternative for designers. An analytical chain allows less precise but way faster calculations enabling to link earlier in the design, the aerodynamic, mechanical and magnetic with the acoustic part. The master thesis is split in two steps. First, the reliability between the aerodynamic and the acoustic data is enhanced for a better estimation of the aerodynamic noise. This is done by using an extraction tool of the aerodynamic and geometric data, inputs of an analytical software OPTIBRUI that estimates the aeroacoustic noise. An automatic chain on a set of Technofan fans is also used in order to validate and optimize the OPTIBRUI configuration in relation to test measurements. In addition to this analytical chain, links between CFD data and measurements have been created. These links are used to compare the data from analytical and numerical calculations with the measurements in order to establish the suitability of the results. The results obtained are very encouraging as they predict the noise level within 3dB. The master thesis ends with the dissociation of the three noise sources occurring in fans (aerodynamic, mechanical and magnetic) knowing the characteristic frequencies of the mechanical and magnetic noise mechanisms. With this dissociation, it is possible to know rapidly from measurements the parts of the fan that are noise dominant and to guide the working times on the jobs treating the zones where the noise is predominant (aerodynamic engineer, electric motor engineer or mechanical engineer).