An experimental investigation into the influence of acoustic disturbances on the development of a turbulent boundary layer

Abstract

An experimental investigation is described into the effects of acoustic disturbances on the mean flow in a turbulent boundary layer developing in a mildly favourable pressure gradient. A Hartmann generator, mounted on the centre line of the RAE 8ft x 8ft wind tunnel, was used as a noise source, and the mean flow in the boundary layer on the tunnel sidewall was examined for any effects of the noise. Even at noise levels up to Cp~ = 0.08 it was not possible to identify any effect of the noise itself on the boundary layer, and it is concludedthat the acoustic disturbances generally found in the working sections of transonic wind tunnels are unlikely to exert a measurable influence on the development of turbulent boundary layers on wind-tunnel models - at least for mild pressure gradients.