Investigation of pressure fluctuations beneath a turbulent boundary layer by means of an optical method

• Published in: The Physics of fluids (1958) 1977-10, Vol.20 (10), p.S216-S224
• Main Authors: Dinkelacker, A., Hessel, M., Meier, G. E. A., Schewe, G.
• Format: Article
• Language: English
• ISSN: 0031-9171; 2163-4998
• DOI: 10.1063/1.861733

An optical method has been developed by Emmerling, Meier, and Dinkelacker which allows the investigation of the instantaneous structure of the wall pressure field under a turbulent boundary layer. The main component of this method is a pressure transducer consisting of several hundred small elastic membranes, the displacements of which are recorded by interferometric means with a high‐speed camera. The method is explained and examples of measurements in a wind‐tunnel are presented. The measurements show the development and convection of pressure patterns of a wide range of sizes (from larger than one boundary layer thickness δ down to 0.1 δ) and with a wide range of convection velocities (from about 0.9 U ∞ down to about 0.2 U ∞, with U ∞ the flow velocity outside the boundary layer). Some speculative considerations are made on what sort of flow configurations might be connected with the observed pressure patterns.