Detonation-based combustion has re-emerged as a promising pathway for enhancing the efficiency and compactness of future aerospace propulsion systems, motivated by the intrinsic pressure-gain characteristics of detonative heat release. This review provides a comprehensive synthesis of the physical foundations, technological progress, and practical limitations associated with pulse detonation engines, rotating detonation engines, and standing or oblique detonation wave concepts. By tracing the evolution from early theoretical models and laboratory-scale demonstrations to engine-relevant configurations, this article highlights how detonation physics, ignition mechanisms, wave stability, and flow–structure interactions collectively govern propulsion performance. Particular attention is paid to recent experimental and numerical studies, with the review focusing on their technological impact and on the feasibility of integrating detonation-based propulsion concepts into practical aerospace systems. The analysis evaluates these approaches’ potential to enhance system-level performance compared to conventional propulsion technologies, while highlighting key challenges associated with scalability, operability, and compatibility with existing aerospace architectures. The review further identifies emerging design strategies, including geometry tailoring, adaptive flow control, and hybrid architectures, as key enablers for extending operability and system integration. Overall, the findings indicate that future progress in detonation-based propulsion will depend less on demonstrating detonation itself and more on achieving robust, controllable, and scalable implementations suitable for realistic aerospace applications.

A Type 22 Broadsword class of frigate uses a combined gas or gas (COGOG) propulsion system that utilizes four different gas turbines, depending on the mode of operation. Its twin ST40M cruise gas turbines are operational most frequently, and an increase in their efficiency would significantly impact fuel usage and ship range. This study evaluates the option to upgrade the cruise gas turbines to a combined gas turbine–electric and steam (COGES) system, which utilizes a steam Rankine cycle to recover energy from the exhaust gases of the gas turbine. An alternative system using hot air is also analyzed for performance comparison. The analysis contains calculations for the energy extraction and dimensions of heat exchangers, for the power extracted from the additional steam or air turbine and for pressure losses of the exhaust gas. Different configurations for the heat exchangers were investigated, as well as various parameters for the steam and hot air. The size and mass of the system were an important aspect of the analysis. It was concluded that an auxiliary system operating at a maximum steam pressure of 20 bar could generate an additional 771 kW of power while adding a mass of 7.4 tons to the frigate. These findings suggest that upgrading to a COGES system could cover the electricity needs of the entire ship and thus reduce the overall fuel consumption, resulting in lower operational costs and less emissions.

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.

The deep underground salt cavities have the advantage of allowing storage of hydrogen at higher pressures than surface installations. Worldwide, in the 2020s there were 4 functional sites of salt caverns used as hydrogen deposits, three in the United States and one in the United Kingdom, at an average of 600,000 m3 capacity each at pressures varies between 50 ÷ 150 bar in the United States and 3 x 70,000 m3 at a pressure of 45 bar in the United Kingdom [1, 2]. From 2020 until now, there is an increase in the salt deposit development for hydrogen storage, expecting to account for about 18% of global energy demand by 2050 [3]. Near Vadu locality, Constanta County, Romania, there are sald deposits located between 705 m and 905 m, respectively 1542 m and 1778 m, offshore in the Black Sea continental shelf. The study consists in determining the storage capacity, at the two drilling depths, for reliable projects of hydrogen storage, for Romania's Energy Strategy, leading to a reduction in the carbon footprint at 70% in 2050 compared to the levels recorded in 2008 of CO2 emissions per transport unit for all the civilian or military transport ships [4, 5].