Influence of active cooling on second mode instabilities investigated on hypersonic, conical flows

Abstract

In the present study the influence of active cooling on hypersonic boundary layer transition is investigated. The analyses are carried out on a 7° half angle, blunted cone with different nose radii and various gas injection mass flow rates. At the considered free stream conditions second mode waves are the dominant boundary layer instabilities, which are consequently the focus of this stufy. The stability analyses are performed by means of the stability code NOLOT, NOnLOcal Transition analysis, of the German Aerospace Center (DLR). The influence of mass injection on the frequencies and growth rates of the second modes is analyzed in detail. The effect on the transition onset locations are discussed. The numerical predictions are compared with experimental results. The experimental data referred to in the present study were obtained in the DLR High Enthalpy Shock Tunnel Göttingen (HEG).