INVESTIGATION AND MODELLING OF THE WALL PRESSURE FIELD BENEATH A TURBULENT BOUNDARY LAYER AT LOW AND MEDIUM FREQUENCIES

In the case of a vehicle moving in a fluid, computation of flow-induced panel vibrations, and the resulting sound generated inside the passenger compartment requires a model that describes the statistics of the turbulent wall pressure fluctuations accurately. However, the models currently available in the literature usually rely on simplifying assumptions and necessitate specific measurements in order to, for example, evaluate the evolution of the coherence length with frequency. This paper describes the work done in order to propose a semi-empirical model for the wall pressure field beneath a fully turbulent boundary layer flow. The main goal is to try to avoid the necessity of preliminary experiments to determine the model coefficients, i.e., propose a model for the power spectral density, coherence length, and phase velocity. After a quick literature review, it proves necessary to acquire a set of experimental data with a fine space–time resolution. Fluctuating wall pressure transducers are developed in this perspective, and experiments are performed in an anechoic wind testing facility. The results are then compared with some published data, analyzed to attempt to offer a schematic description of the physical phenomena involved, and to define the pertinent parameters of the flow and properties of the wall pressure field. These observations are then used to propose a new model for the wall pressure field beneath a fully turbulent boundary layer flow.