Dynamics and interaction of shock oscillation and flow separation in transonic profile flow

• Applicant: Dr. Sven Scharnowski
• Subject Area: Fluid Mechanics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 535550047

Shock-induced buffeting represents a flow instability that causes strong periodic pressure fluctuations and consequently alternating loads in components with transonic flow around them, and thus significantly limits the operating range. For efficient use and the definition of a safe range of operation, it is necessary to be able to predict at which flow conditions shock-induced buffeting and the associated structural interactions occur. In the research project applied for here, the transonic flow around different wing profiles is to be investigated experimentally in order to physically understand the cause and dynamics of this flow instability. For this purpose, experiments are planned at the Trisonic Wind Tunnel Munich (TWM) using state-of-the-art optical flow measurement methods. By using them, the density change, the surface pressure as well as the velocity field can be determined with high temporal resolution. This makes it possible to systematically investigate the relationship between the boundary layer state (especially the flow separation) and the shock location. Furthermore, the acoustic wave propagation velocity and the convection velocity of coherent structures in the detached boundary layer will be determined in order to verify and, if necessary, adapt existing prediction models for the Buffet frequency. In addition to the model geometry, the angle of attack and the Mach number will be varied to derive and verify physical models for the occurrence of Buffet as well as its dynamics. To ensure the best possible quality of the experimental results, the wind tunnel tests will be accompanied by optimizations and further developments of the measurement and evaluation methods. It is expected that this research project can make a significant contribution to the understanding of the underlying relationships of buffeting, as well as their effect on frequency and amplitude.

• DFG Programme: Research Grants