Hot-Wire Measurements in sequentially sucked Boundary Layers

Abstract

Wind tunnel tests with a modular flat plate with applied multiple boundary layer suction are presented. Hot-wire measurements are conducted over the first and second suction panel to determine mean velocity profiles as well as disturbance frequency spectra and amplitudes. The mean velocity profiles show excellent agreement with calculations, whereas a shift in the frequency spectrum can be seen compared to LST methods. Additionally, the maximum allowable disturbance level at the beginning of suction is evaluated, which is crucial for the design of an HLFC system with sequential suction areas. If the amplitude at the beginning of suction is higher, an intermittent region develops downstream. Inside this region, hot-wire measurements are used to investigate the degree of intermittency.