As the temperature of gas turbines continues to rise, turbine cooling faces significant challenges. Facing significant flow and heat transfer non-uniformity issues in turbines, the ability of artificially defined topological structures to control physical fields is insufficient. Therefore, it is necessary to utilize intelligent geometry algorithms to address such bottleneck issues in turbine cooling. This study applies self-organizing structures with biomimetic capabilities to flat double-wall cooling systems, addressing the issue of non-uniformity in turbine cooling. Referencing the impingement-film cooling layout in the first-stage vane of the turbine, typical features of the inlet and outlet of the double-wall cooling area were extracted. A geometric modeling method based on the self-organized algorithm, which uses the diffusion-anti-diffusion equation, was applied to generate topological structures. These were then used as flow disruption structures to create a new impingement-film-disruption cooling structure. This study conducts numerical simulations on four different configurations of flat double-wall structures, comparing the heat transfer and flow performance of double-wall cooling systems incorporating self-organized structures under various parameters. The results indicate that for flat double-wall structures, the more fully the self-organized structures grow within the limited space of the impingement chamber, the greater the improvement in heat transfer performance. The flow field of the impingement-film-self-organized structure composite within the flat double-wall is significantly different from the traditional impingement-film flow field. Considering different combinations of self-organized parameters, when the self-organized structure can guide the impingement cross-flow towards the film cooling holes within the impingement chamber, it results in reduced flow losses and enhances heat transfer.

In confined spaces, due to various interfering factors, oblique detonation waves inevitably reflect off the walls, resulting in the formation of a Mach stem. When the Mach reflection is excessively strong, it can lead to the instability of the oblique detonation waves. Therefore, it is necessary to study the stability characteristics of the reflected wave system. Based on a simplified combustor-nozzle model, this paper studies the effects of jet injection on the stability of oblique detonation waves in confined space. The results indicate that injecting a jet on the wedge surface reduces the angle of the oblique detonation waves, decreases the intensity of Mach reflection, and enhances the stability of the wave structures. The oblique detonation waves induced by jets of varying pressure exhibit different characteristics. Compared to a hot jet, cold jet can induce a stronger shock wave at the same pressure. Both excessively high or low jet pressure can lead to a reduction in the stability of the wave structures.

To elucidate the detailed mechanism of the fan swirling flow on generator internal cooling, a numerical investigation was conducted on a compact fan-generator system designed for small aircraft, characterized by high rotational speeds and elevated power densities. A simplified three-dimensional axial fan-generator integration model was developed, employing coupled fluid-thermal numerical methodology to analyze the internal flow field and heat transfer processes. And the isolated generator with uniform inflow, which usually represents the ram-air cooling in aircraft are also compared with fan-generator integration. The results reveal that the fan swirling flow enhances turbulence generation, effectively modifying flow structures to eliminate stagnant zones and mitigate heat accumulation. It leads to a better cooling performance, especially for the upstream components where the high power-density electric element should be arranged. Additionally, it is revealed that the circumferential and radial components of the velocity play important roles in cooling some hot surfaces of key components of the generator, even at the similar mass flow rate. The augmentation of total fluid velocity induced by the fan swirling further intensifies convective heat transfer. This study provides comprehensive insights into temperature distribution patterns and flow characteristics, offering valuable guidance for optimizing energy-efficient and reliable generator cooling system designs.

To address the issues of severe noise pollution and high carbon emissions associated with turbine engine propulsion systems used in previous generations of supersonic technology, this study proposes the ammonia decomposition turbine-less SOFC/supersonic jet engine hybrid system (NH₃ SOFC/SJE system). The proposed design aims to achieve supersonic cruising, transoceanic flight, and zero-carbon emissions, offering a sustainable solution for next-generation supersonic propulsion systems. The results indicate that as the pressure ratio increases, specific thrust continues to rise, while the fuel consumption rate initially decreases and then increases. The optimal pressure ratio is found to lie between 15.1 and 19.8. Higher fuel utilization efficiency contributes to the improved performance of the hybrid system. When the ammonia decomposition temperature is around 900 K, both the fuel economy and propulsion performance of the hybrid system are effectively met. The hybrid system achieves the most economical cruising state at an altitude of 20 km and a Mach number of 1.8. In this optimal cruising state, the Cost per unit distance of the conventional turbojet engine is 39.9% higher, while that of the H₂ SOFC/SJE system is 6.03% higher compared to the proposed system. In summary, ammonia, as a zero-carbon fuel, offers significant advantages for supersonic flight.

Achieving sustainable aviation requires high-power, high-efficiency, and lightweight electric propulsion systems, with superconducting technology showing great potential for significantly enhancing electrical component performance. This paper presents a comprehensive review of megawatt-class superconducting propulsion architectures for aircraft, highlighting their principles, benefits, limitations, and technology readiness levels. A comprehensive analysis is provided on four critical aspects of superconducting power transmission and distribution—superconducting cables, cryogenic power electronics, superconducting fault current limiters, and superconducting magnetic energy storage—with an emphasis on their developmental progress, technical barriers, and future prospects. A comparative assessment of prospective architectures toward 2035 is conducted under three scenarios: conservative, baseline, and optimistic. Findings suggest that for a 5 MW regional aircraft utilizing hydrogen fuel cells, superconducting hybrid-electric propulsion can significantly reduce system weight and enhance power density. For a 10 MW single-aisle aircraft with turbine engines, a parallel hybrid configuration offers superior efficiency and density. Considering the system-control complexities associated with mechanical coupling, the DC transmission series turbo-electric hybrid propulsion system is identified as a particularly promising pathway, aligning with the anticipated trajectory of high-power aviation systems.

As the primary power source, propellants enable faster and more distant space exploration. While the traditional hydrazine-based bipropellants are gradually replaced due to their extreme volatility and carcinogenicity, ionic liquid-H₂O₂ has become an important research direction for green propellants because of the environmental friendliness. This review mainly focuses on two aspects of ionic liquid-H₂O₂ bipropellants: (1) the structures and properties of ionic liquids that spontaneously ignite with H₂O₂. These ionic liquids include the BH₃CN⁻, BH₄⁻, and SCN⁻-based compounds, which possess strong reduction ability, enabling hypergolicity with high-concentration H₂O₂; (2) the structures and properties of catalysts that enhance the ignition of ionic liquids with H₂O₂. These catalysts include pure iodine-based, CuI-based, and metal (Cu, Ni, Mn) complex-based catalysts, which boost N(CN)₂⁻-based ionic liquids from non-ignition to ignition, and BH-based ionic liquids from long to short ignition delay times with high-concentration H₂O₂. The properties of the mentioned ionic liquids and catalysts, such as decomposition temperature, density, viscosity, enthalpy of formation, and specific impulse, are analyzed. Ignition delay times are measured using drop tests, and imidazolium thiocyanate (IL 8) exhibits the shortest ignition delay time of 7.3 ms with 97% H₂O₂. Based on the calculations, N-methyl-N-ethylpyrrolidinium thiocyanate (IL 16) has the highest propulsion performance with a specific impulse of 320 s. Here, the detailed research of the ionic liquid-H₂O₂ system is summarized, which is valuable to get the overall understanding and the new development of green propellants for rocket applications.

In order to reduce the axial size of the supercritical carbon dioxide (SCO₂) Brayton cycle system and enhance its power-weight ratio, this paper proposes a counter-rotating design approach for SCO₂ turbines. The design process primarily involves 1D aerodynamic design based on theoretical analysis of velocity triangles and blade geometry modeling. A three-stage 10 MW SCO₂ axial turbine is selected as a test case and redesigned as a 1 + 1/2-stage counter-rotating turbine (CRT) configuration. Compared with the three-stage turbine, the axial length of the CRT is reduced by 63.5%. Subsequently, the performance of the designed counter-rotating SCO₂ turbine is validated through detailed numerical analysis utilizing the three-dimensional computational dynamics method, considering real gas effects of CO₂ by employing a physical property database for property calculations. The computational fluid dynamics results demonstrate that under design conditions, the isentropic efficiency is 92.4%, which represents a 12.4 percentage points improvement over the design target and satisfactorily meets the design objectives. Further analysis on the flow field was conducted, and it was found that the turbine streamlines are uniform, the entropy increase is concentrated at the trailing edge of the blades, and the average absolute outlet flow angle is 0° approaching the axial direction. The behavior of the CRT under off-design conditions is also discussed.