Flow Disturbances Associated with Preston Tubes in Turbulent Boundary Layers (Stromungsstorungen von Prestonrohren in Turbulenten Grenzschichten) (Des Perturbations des Courants a Cause des Preston Tubes dans des Couches Limites Turbulentes).

摘要

An investigation has been made concerning the disturbances from a surface cylinder aligned with the flow in turbulent boundary layers. The object is to study the flow around Preston tubes. Mean velocities and rms-values of the fluctuations were obtained in the centre plane of the cylinder when immersed in turbulent pipe flow. A rough estimate of the drag due to the surface sylinder was also obtained in this case. The pressure distribution near the cylinder was measured in a flat plate boundary layer, and flow visualizations were made with the oil flow technique. In addition, smoke pictures were obtained of the flow for the cases when the boundary layer thickness on the plate was negligible compared to the tube diameter. The present results are of interest in connection with the use of Preston tubes, in particular with regard to the measurement of static pressure. (Author)