Numerical Analysis of Separation Events for Two-Dimensional Supersonic Wavy Geometries

Axial supersonic bladeless turbines offer a promising solution for power extraction in supersonic environments by exploiting pressure gradients generated by shocks waves and expansion fans induced by wavy-contoured geometries. This paper addresses the aerodynamic performance and the aerodynamic interactions of a two-dimensional wavy-surfaced geometry based on a sinusoidal profile. Numerical simulations, both inviscid and viscous, are used to analyze flow separation, total pressure losses, and pressure profiles across a range of geometric configurations, defined by the height-to-length ratio (h/l). Results indicate that increasing h/l amplifies pressure loading and torque potential, but also triggers complex separation mechanisms. At high h/l, cavity-like separation dominates and severely impacts entropy generation and, in contrast, intermediate h/l configurations exhibit separation driven by shock/boundary layer interactions (SBLI), suggesting a distinct and potentially more controllable mechanism. A classification of these separation regimes is proposed to inform a new class of optimal geometries aimed at maximizing the pressure differential by controlling the separation position. The investigation is further broadened to encompass multiple operating conditions, with variations in both inflow Mach number and stagnation pressure. The findings provide new insight into the complex dynamics of large wavy-contoured supersonic surfaces (h/l ≥ 0.01).