Article Experimental design and stochastic modeling of hydrodynamic wave propagation within cavities for wind tunnel acoustic measurements Colin P VanDercreek 1 , Alireza Amiri-Simkooei 1 , Mirjam Snellen 1 and Daniele Ragni 2 Abstract This study investigates how embedding microphones in different cavity geometries along the wall of a wind tunnel reduces the measured turbulent boundary layer pressure fluctuations. The effect of these cavities on the measured signal-to-noise ratio of an acoustic source with flow present was also quantified. Twelve cavity geometries defined by theirdepths, diameters, chamfer, open- ing percentage, and mesh covering were tested. The cavity geometries were selected using a design of experiments methodology. The application of design of experiments enabled a statis- tically sound and efficient test campaign. This was done by applying a D-optimal selection crite- rion to all potential cavity geometries in order to select 12 cavities to allow for the individual effect of the geometric parameters such as depth and diameter to be quantified with statistical confidence. The resulting wind tunnel test data were fit to a generalized additive model. This approach quantified the relative effect of these parameters on the turbulent boundary layer pressure spectral energy and signal-to-noise ratio while accounting for non-linear frequency dependence. This experimental investigation quantified how much increasing depth reduces the turbulent boundary layer spectral energy and increases signal-to-noise ratio. It also 1 Section Aircraft Noise and Climate Effects (ANCE), Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands 2 Section Aerodynamics, Wind Energy, Flight Performance and Propulsion (AWEP), Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands Corresponding author: Colin P VanDercreek, Section Aircraft Noise and Climate Effects (ANCE), Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands. Email: c.p.vandercreek-1@tudelft.nl International Journal of Aeroacoustics 2019, Vol. 18(8) 752–779 ! The Author(s) 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1475472X19889949 journals.sagepub.com/home/jae