Numerical and experimental investigation of a beveled trailing edge flow and noise field

Abstract

Efficient tools and methodology for the prediction of trailing edge noise experience substantial interest within the wind turbine industry. In recent years, the Lattice Boltzmann method has received increased attention for providing an efficient alternative for the numerical solution of complex flow problems. Based on the fully explicit, transient, compressible Lattice Boltzmann solution in combination with the Ffowcs Williams and Hawking analogy, an estimation of the acoustic emission in the far field is obtained. To validate this methodology for the prediction of trailing edge noise, the flow around a plate with an asymmetric 25 degree beveled trailing edge in low Mach number flow is analyzed. Flow field dynamics are compared to experimental data obtained from Particle Image Velocimetry measurements and show similar trends and behavior for both the mean and fluctuating velocity. Results of the acoustic prediction are compared to acoustic measurements obtained through phased array beamforming in combination with a source power integration technique. Vortex shedding is captured, broadband noise is present on both the experimental and numerical obtained noise spectra and a typical cardioid-like directivity behavior is found.

Near-wall pressure fluctuations over noise reduction add-ons

“…Surface pressure fluctutations are sampled at 30 kHz. The prescribed methodology was validated in a previous study by van der Velden et al 34 The trailing-edge thickness in the simulation is equal to the one of the aluminum model (1 mm thickness), in order to minimize any tonal noise component due to vortex shedding (t/δ ≈ 0.1 where δ is the expected boundary-layer thickness at the tested Reynolds, cfr. Table II).…”