Numerical investigation of the aeroacoustic properties of a slot diffuser

Institute for Energy Efficient Buildings and Indoor Climate, RWTH Aachen University, Germany

^* Corresponding author: lisa.krueger@eonerc.rwth-aachen.de

Abstract

Reducing noise emissions from building ventilation systems not only improves acoustic comfort but also extends the operating limits of mechanical ventilation systems. The geometric characteristics of an air diffuser have a significant influence on its acoustic behavior. Implementing geometric modifications early in the design process based on a simulation model offers a promising approach for optimization. This paper introduces a numerical model of a commercial slot diffuser. The study aims to investigate the applicability of aeroacoustic simulation for deriving noise reduction strategies by the successful prediction of acoustic characteristics. We compute the acoustic pressure below the diffuser within a Large Eddy Simulation (LES) in combination with an approach based on the Linearized Perturbed Compressible Equations (LPCE). Acoustic measurements are performed to verify the transient simulation solution. A comparison of the power spectral densities obtained from the experiment and simulation confirms that the model successfully reproduces the characteristic properties of the commercial air diffuser at the investigated operating points. Limitations arise from insufficient resolution in the low-frequency range due to the short time interval considered and external influences on the acoustic measurements. With the aim of noise reduction, we implement modifications in the form of droplet-shaped elements at a leading edge of the air diffuser geometry and investigate their influence on the acoustic behavior of the air diffuser.