The Effect of the Step Height on the Wall Pressure Fluctuations near Its Side Edge in the Turbulent Boundary Layer

Wall pressure fluctuations in a turbulent flow are a source of noise and vibrations in elastic structures immersed in a flow. This paper presents the results of an experimental study on the effect produced by the height of a step on the spatiotemporal structure of wall pressure fluctuations in the vicinity of its side edge in the turbulent boundary layer. Measurements were performed in a subsonic low-noise wind tunnel of the Moscow Complex of the Zhukovsky Central Aerohydrodynamic Institute. The height of a step was varied from 3 to 17% of the incident-boundary-layer thickness. It has been shown that the area of the most intensive pressure fluctuations is located near the frontal side corner of the step. The characteristic Strouhal number determining the spectra of pressure fluctuations behind the leading edge of the step was established. An essential effect of the step height on the spatiotemporal structure of the pressure field in the vicinity of the side edge was shown. The obtained results evidence the existence of a strong correlation with the field of pressure fluctuations in the incident turbulent boundary layer in the case of steps with a small height.