Aerodynamic and Aeroacoustic Interaction of Heat Exchangers and Low-Pressure Axial Fans

Description

The sound emission of axial fans in heat pumps and air conditioning systems has not yet been sufficiently addressed and contributes to the reduced acceptance of these systems among the general public. Continuous and excessive noise emissions have a negative impact on both the environment and people in the immediate vicinity of the noise source. As sales of air conditioning systems and heat pumps continue to rise, the acoustic impact of these devices is also increasing from year to year. In these devices, the axial fan is usually operated in direct coupling with a heat exchanger. The presence of a heat exchanger on the suction side of the fan further increases its noise emissions compared to the fan noise alone. These additional noise emissions due to the interaction of the heat exchanger with the axial fan are referred to as installation effects. The aim of this scientific work is to analyze and understand the physical mechanisms of installation effects induced by heat exchangers. For this purpose, an active turbulence grid was developed that can replicate various flow fields of heat exchangers. As a result of extensive experimental investigations, a generally valid schematic sound pressure spectrum for an axial fan was derived, which summarizes the influences of the installation effects of heat exchangers on the sound generation of axial fans.