Reusable liquid-propellant launch vehicles constitute a pivotal direction for future space transportation systems. During vertical re-entry of a rocket, the aft-mounted engines descend in an irregular configuration facing the freestream. The local thermal environment and flow characteristics are highly complex. A simulation study of the flow over a Falcon 9 v1.2 derived geometry was conducted for four representative re-entry phases: high-altitude powered deceleration, high-altitude aerodynamic deceleration, low-altitude aerodynamic deceleration, and low-altitude powered deceleration. The vehicle thermal environment is markedly transient and non-uniform: plume morphology evolves continuously with altitude and engine operating condition. Powered deceleration phases exhibit substantially stronger flow disturbances and heat-flux maxima than aerodynamic deceleration phases owing to intense plume-freestream coupling. Secondary combustion exerts a global thermal influence on the far-field plume at low altitude. Across the four characteristic stages, the peak heat flux persistently localizes at the nozzle lip and the aft-edge of the rocket base, reaching 380 kW/m², these data constitute a quantitative basis for engine thermal-protection design.

The hydrogen–oxygen-steam gas turbine system embodies a promising pathway toward zero-emission technology. The inherent challenges of flashback and ablation associated with hydrogen fuel and high-oxygen-concentration flames have steered current hydrogen turbine advancements toward micro-mix combustion technology. To meet the experimental demands for hydrogen–oxygen micro-mix high-pressure combustion under steam dilution, this study utilized 3D printing technology for the fabrication of the combustion chamber, and developed an innovative experimental technique utilizing throat pressure buildup and regenerative cooling for steam generation. The system is capable of accommodating hydrogen–oxygen-steam micro-mix high-pressure (0.3–1 MPa) combustion testing across a power spectrum of 5.40–10.80 kW, with pressure fluctuation below 0.01 MPa during stable combustion stage. Regenerative cooling and steam dilution can substantially lower the maximum temperature of hydrogen–oxygen flame even at high pressure near 1 MPa, thus offering a viable means to achieve hydrogen–oxygen combustion in gas turbines. By integrating wall-mounted temperature sensors, combustion chamber pressure monitoring, and infrared thermographic imaging, comprehensive data on combustion chamber wall temperatures, combustion pressures, and qualitative steam temperature fields at the outlet were systematically acquired. The combustion efficiency was evaluated through combustion temperature and pressure metrics. The findings demonstrate that the initial temperature within the combustion chamber and the structure of micro-mixing injection exert a considerable influence on combustion efficiency, whereas the impact of combustion chamber pressure is marginal. In particular, the cross-jet injection technique augments combustion efficiency by 6%–8% in contrast to the axial-tangential swirl approach. Moreover, an elevation in the initial temperature of the combustion chamber from 100 ℃ to 300 ℃ results in a 4% improvement in combustion efficiency. Thus, a novel integrated system combining 3D-printed combustion chambers with regenerative steam cooling for high-pressure hydrogen–oxygen combustion studies was developed. This technology may provide experimental validation and design guidelines for next-generation hydrogen gas turbine development.

This work aims to establish a stable premixed ammonia/air flame in a tangential swirl combustor by employing an ethanol spray to extend the fuel-lean extinction limit of the ammonia flame and reduce pollutant emissions. A Planar Laser Induced Fluorescence (PLIF) system is introduced to acquire the flame structure of this blending system. The results demonstrate that OH radicals originating from the ethanol flame support the ammonia flame, in which fluorescence images are indicated by the NH₂ radicals. Moreover, the lean extinction limit is significantly extended from an equivalence ratio of 0.6 to 0.1. In particular, the addition of a minor quantity of ethanol (3 mL/min) to ammonia flame sustains the blending flame due to the ultralow extinction limit of the ethanol swirl spray flame. However, both experimental data and chemical reaction analysis reveal that an increase in OH radical concentration leads to an elevation in NO_x (nitrogen oxides) concentration. This poses a challenge in balancing the effects of ammonia consumption and NO_x generation in the blending combustion system. Ethanol flames indeed generate active radicals (O, OH, HO₂, etc.) to accelerate ammonia oxidation. However, these active radicals also exacerbate the reaction between NO and NO₂, inhibiting their conversion to N₂. Even so, the objective of achieving clean combustion with low concentrations of both NO_x and unburned NH₃ can still be met under the condition of the total air flow rate 90 L/min and the global equivalence ratio 0.7.