Compilation and Analysis of Second-Mode Amplitudes on Sharp Cones in Hypersonic Wind Tunnels

Abstract

This research effort coordinated by the NATO AVT-240 specialists’ group compiles and analyzes second-mode amplitudes on sharp slender cones at 0 degrees angle of attack. The analysis focuses on pressure fluctuations measured with piezoelectric sensors in 11 hypersonic wind tunnels operated by 9 organizations located in 3 NATO countries (Belgium, Germany, and USA) and Japan. The measurements are at freestream Mach numbers between 5 and 14, unit Reynolds numbers Re/m between 1.5 and 16 million per meter, and wall-to total temperature ratios between 0.1 and 0.8. The study shows that second-mode growth rates can be predicted with Parabolized Stability Equations (PSE) over the wide range of conditions. The maximum second-mode amplitudes vary weakly at edge Mach number Me greater than ~5.8, but significantly decrease at lower Me. The maximum N factor envelope from PSE and the measured amplitudes are used to estimate the initial amplitudes A0. At each Mach number, A0 varies approximately as Re/m^(-1). This leads to transition N factors that increase with Re/m. This behavior is consistent with the results from Marineau (AIAA Journal, Vol. 55, No. 2, 2017).