Hot-Wire Measurements of two-Point Correlations in the Flat Plate Boundary Layer at High Reynolds Numbers

Abstract

Two-point correlations were measured in the 8 ×test section of the low- speed German-Dutch wind tunnel at Reynolds numbers up to Re = 50 × 106. In the experiments a zero pressure gradient turbulent boundary layer along a flat plate with a length of 13.5 m was generated. The two-point correlations were measured at freestream velocities of 40 m/s and 60 m/s with two triple hotwire probes, which could be moved independently above the surface of the flat plate. With this setup it was possible to collect data for the normal and shear stresses in the normal and in the spanwise direction for all levels. It is the objective of this investigation to obtain a database for turbulent boundary layers at large Reynolds numbers with exactly known boundary conditions that can be used, e.g., to validate subgrid scale models in large-eddy simulations and to experimentally verify the new exponential law in the outer region of the boundary layer [1]. Additionally, velocity profiles of the boundary layer and two-point correlations in the normal and spanwise direction were measured to study the variation of the integral length scale in the spanwise direction.