Eine experimentelle Untersuchung beschleunigter turbulenter Wandgrenzschichten

Accelerating turbulent boundary layers on plane walls were generated in a rotationally symmetrical working section with the aid of displacement elements in order to investigate the effects of negative pressure gradients on the mean velocity profiles and turbulence strcture for varied initial conditions as well as the profile change upon removal of the pressure gradient. Four different cases with different acceleration curves (velocity increase by a factor of 1.7 resp. 2.9) and different Reynolds numbers prior to acceleration (860-5810) were investigated. Flow parameters and turbulence structures were determined on the basis of time curves of wall shear stress and velocity obtained with the aid of hot bands on the wall, normal wire probes and X-wire probes. Reynolds stresses, spectra, autocorrelations, 2-point spatial correlations and higher statistical moments were calculated on this basis and evaluated. This is followed by a short discussion and an interpretation of important findings. A comparison between various methods of measuring wall shear stress showed good agreement between hot wires on the wall and oil film interferometry in all flow regions. (orig./AKF)SIGLEAvailable from TIB Hannover: RR 4393(5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman