Aeroacoustic prediction of complex hvac systems

Reliable tools for predicting aeroacoustic noise are of major interest for the automotive industry and HVAC (Heating, Ventilation and Air Conditioning) suppliers whose aim is to reduce the negative impact of HVAC noise onto passengers. In this work, a hybrid approach based on the acoustic perturbation equations is tested for this purpose. In a first step the incompressible flow field is computed using a commercial finite volume solver. The large eddy simulation (LES) turbulence model is used to obtain time resolved flow data required to accurately predict acoustic phenomena. Subsequently the aeroacoustic source are computed and, after their conservative interpolation to a finite element grid, the acoustic propagation is calculated. This procedure will be tested for an HVAC unit, a radial blower and finally for an overall system combining these two components. Measurements of the aeroacoustic noise excited by these components are performed in an anechoic chamber. The comparison of spectra obtained from the simulations and the experiments reveals a good agreement up to a specific frequency. This frequency depends on the mesh sizes chosen for the flow simulation.