Design of an H2–O2 Standing Oblique Detonation Test Bench and Study of Recirculation-Zone Influence on Shock Structure

Building on the previous theoretical parametrisation of oblique detonation wave (ODW) stability limits for hydrogen–oxygen mixtures, the present work advances the investigation by combining CFD analysis with the complete mechanical design of a planar ODW test bench. While the earlier study established feasible inflow conditions and wedge-angle ranges through detonation theory and oblique shock relations, the current work focuses on the numerical characterisation of ODW-relevant flow fields and the constructive development of the experimental facility. CFD simulations were performed for seven wedge deflection angles to assess shock formation. A key finding is the identification and systematic characterisation of a recirculation-induced secondary deflection mechanism, which emerges for wedge angles above ~20°. The recirculation zone forms an effective secondary wedge whose boundary angles remain nearly constant, thereby altering the resulting shock angle and explaining the deviation from classical oblique-shock predictions. This behaviour was quantified through velocity-component sampling and shown to be consistent across multiple geometries. Based on the numerically optimised configuration, the full 3D design of the test bench is developed, including diagnostics integration, sealing solutions, and a modular wedge system enabling rapid geometry replacement. By linking theoretical analysis, numerical validation, and experimental design, the study establishes a robust foundation for forthcoming ODW experiments and contributes to the development of pressure-gain combustion concepts for rocket-type propulsion.