As aviation propulsion systems become increasingly electrified, quiet propulsion systems are becoming a key focus of future urban and regional mobility concepts. This is particularly true for aircraft operating in and around cities, where social acceptance depends largely on noise emissions.
The goal of the VALERIE project, which is funded by the Aviation Research Program, is to develop efficient methods for the quantitative assessment of noise generation and propagation from small aircraft propulsion systems. The focus is on low computational effort combined with high prediction accuracy, taking into account all essential geometric influencing factors. These methods are intended to enable targeted noise reduction through overall system optimization as early as the preliminary design stage. To this end, VALERIE is developing reduced-order models (ROMs) for the noise emissions of ducted fans and free propellers. These models are based on higher-order methods and offer a significant reduction in computational effort compared to classical computational aeroacoustics (CAA) methods. The ROMs enable precise evaluation and optimization of noise emissions, even for novel propulsion configurations. In addition, they allow for a uniform and comparable analysis of free propellers and ducted propellers.
At IFAS, VALERIE is used to specifically investigate three-dimensional design measures on shrouded propellers with regard to their influence on noise generation. High-resolution uRANS simulations are used to generate validation data for aerodynamics and acoustics, with a particular focus on rotor-stator interaction and its acoustic effects, such as tonal components, broadband noise, and propagation characteristics.