On Linear Stability of Compression Corner Flows Obtained by Kinetic Theory

Two-dimensional supersonic flow over several compression corners are computed by Direct Simulation Monte Carlo (DSMC) and their linear global stability analysed by solution of the compressible BiGlobal eigenvalue problem on generalised coordinates. The base flow features a large separation bubble, while time resolved data showed that the flow reached a steady state at the parameters examined. The maximum recirculation, calculated by reference to the free stream velocity, is found to be around 10% for all cases. Linear stability analysis performed confirms this conjecture, yielding a globally stable solution for a wide range of spanwise wavenumbers. The two-dimensional (spanwise wavenumber β = 0) limit is found to be the least stable, an increase of β leading to more stable spectra while retaining the same leading stationary mode. Higher scaled ramp angles, leading to substantially higher recirculation levels, are currently being analyzed.