Fundamental study of Tollmein-Schlicting waves in a boundary layer. Part 1. Design and characterization of compliant materials for boundary layer control

A series of cooperative US/UK experiments are being undertaken in the National Institute of Standards and Technology (NIST) Low Turbulence Water Tunnel to obtain high quality data on the suppression of artificially produced Tollmien-Schlicting (TS) waves and transition delay by compliant surfaces and verify the theoretical predictions. The experimental approach consists of injecting TS waves into a laminar boundary layer and monitoring the growth rate of TS waves using hot-wire probes, flow visualization, and optical measurement of the compliant surface displacement. This paper presents progress to date on preparation and characterization of low modulus materials, design, construction and test of laminar flow test fixtures, test plates, and measurement apparatus, and measurements obtained on a very soft compliant surface under turbulent flow conditions.