Measurements of wall pressure fluctuations under a turbulent boundary layer were made on the fuselage of a sailplane. This flow offers a noise-free environment with a low free stream turbulence level. The axisymmetric boundary layer undergoes natural transition and develops in a zero pressure gradient region. Spectra of the wall pressure were found to decrease at low frequency in agreement with calculations based upon a turbulence–mean shear interaction mechanism. Velocity fluctuations at several positions within and outside the boundary layer were measured and correlated with the wall pressure. A special conditional correlation method was also employed to find the contribution of various velocity fluctuations to the wall pressure. A conditioning signal was formed based upon the signs of u and v and the turbulent–non-turbulent nature of the flow. This signal was time lagged and correlated with the wall pressure signal. It was found that in the outer portion of the boundary layer (y/δ > 0·5), irrotational motions were more highly correlated with the wall pressure than vortical motion.
No takes yet. Share an insight, caveat, or question.
Panton et al. (1980) studied this question.