Development of Tollmien-Schlichting waves at the suction-non-suction junction of an HLFC flat plate

Kurzfassung

Increased receptivity at the suction-non-suction junction is identified as the main contributor to reduced critical N -factors in wind tunnel tests on a modular flat plate with boundary layer suction. This is achieved by comparing Tollmien-Schlichting wave amplitudes measured with a hot-wire probe to linear stability calculations. The implementation of basic increased receptivity at the suction panel edges results in good accordance of measurement and calculations. Receptivity coefficient factors are determined empirically. It is shown that even simple assumptions can result in a much more constant critical N-factor. Furthermore, it is expected that a smooth junction is able to mitigate the detrimental effect.