High-performance propulsion technology is one of the core issues for high-speed aircrafts which are of important strategic value. The "thrust trap" problem in current propulsion systems based on the Brayton cycle can be avoided by the rotation detonation. Consequently, the rotating detonation propulsion technology has significant advantages and is expected to help high-speed aircrafts achieve long-term development. To this end, this article summarizes the rotation detonation combustion process and analysis models. The performance advantages and research progress of propulsion systems based on the rotation detonation are introduced as well. Furthermore, the design requirements of the intake and exhaust systems for rotating detonation ramjets by taking the unsteady combustion into effect are discussed. Feasible measures to suppress the back propagation of pressure waves in the inlet are validated through numerical simulations. Finally, prospects of propulsion systems based on the rotation detonation are proposed.

The diagnostic testing and regular interpretation of combustion flow fields have significant value for the design, development and engineering applications of engines. This paper summarizes the comprehensive experimental techniques for the study of spray combustion flow fields in engine combustion chambers, mainly using modern optical diagnostics. The basic principles and experimental systems of measurement methods such as schlieren method, laser Doppler velocimeter, laser-induced fluorescence and laser particle size analysis are described for the testing and analysis of two-phase flow fields and spray combustion flow fields. This paper also introduces the measurement of combustion flow fields in commonly used optical transparent model combustion chambers in the laboratory, such as single nozzle cylindrical combustion chambers and annular combustion chambers. The aim of this paper is to provide a reference for readers to understand the optical experimental testing techniques of spray flow fields, and to provide a foundation for the development of new combustion flow field measurement instruments or new measurement technologies.

Carbon capture technology is a focal point in the realm of carbon capture, utilization, and storage. Enhancing CO₂ capture efficiency and reducing energy consumption are pivotal for the viability of industrial applications and the attainment of the "carbon peaking and carbon neutrality" objective. Cryogenic CO₂ capture by desublimation is a post-combustion capture technology that has the advantages of high CO₂ capture rate, environmental friendliness, and the production of high-purity CO₂ products. Consequently, it holds substantial potential for both academic research and industrial applications. Nevertheless, conventional CO₂ desublimation capture methods using solid media present limitations, including challenges in collecting and removing solid CO₂, compromised heat transfer between solid media and gaseous CO₂, and corrosion issues. Although utilizing liquid media for desublimating and capturing CO₂ can overcome these challenges, pertinent research remains insufficient. This study employs the cryogenic carbon capture method, utilizing liquid media to desublimate CO₂. It establishes a one-dimensional model for the isopentane spray tower to examine the temperature and CO₂ concentration fields within the tower. The aim is to elucidate the relationships and physical mechanisms governing the tower's overall CO₂ capture rate in relation to the initial conditions of the inlet gas, isopentane droplets, and spray tower settings. Numerical results from the one-dimensional isopentane spray tower revealed the following: (1) The temperature variation of isopentane droplets was minimal and primarily occurs around the gas inlet area, indicating that desublimation was contingent upon CO₂ concentration fields and mass diffusion. (2) The temperature of the CO₂ mixture gas undergone significant changes throughout the tower at a constant rate, highlighting the dominance of gas temperature fields by thermal convection with negligible effects from droplet desublimation on gas temperature. (3) The initial diameters and temperatures of isopentane droplets significantly affected the spray tower's overall CO₂ capture rate. Initial diameters smaller than 2.0-mm and initial temperatures below 150.00 K for isopentane droplets result in a CO₂ capture exceeding 90% for a 2.0-m high spray tower, validating the efficacy and efficiency of the isopentane spray tower in cryogenic CO₂ capture. (4) The spray tower's overall CO₂ capture rate was influenced by the tower's height, initial velocity and temperature of isopentane droplets, and inlet gas velocities. The efficiency of the desublimation process was strongly dependent on the heat transfer efficiency and contact time between isopentane droplets and CO₂ mixture gases. Through numerical simulation and investigation of temperature and CO₂ concentration fields within the isopentane spray tower, this study unveils and analyzes factors influencing the tower's CO₂ capture rate and the pertinent mechanisms of CO₂ desublimation on liquid droplets. Additionally, it demonstrates the effectiveness of the isopentane spray tower in capturing CO₂, emphasizing the substantial potential for cryogenic CO₂ capture using liquid spray in the field of carbon capture.

The study presents a new type of detonation engine called the Ram-Rotor Detonation Engine (RRDE), which overcomes some of the drawbacks of conventional detonation engines such as pulsed detonation engines, oblique detonation engines, and rotating detonation engines. The RRDE organizes the processes of reactant compression, detonation combustion, and burned gas expansion in a single rotor, allowing it to achieve an ideal detonation cycle under a wide range of inlet Mach numbers, thus significantly improving the total pressure gain of the propulsion system. The feasibility and performance of RRDE are discussed through theoretical analysis and numerical simulations. The theoretical analysis indicates that the performance of the RRDE is mainly related to the inlet velocity, the rotor rim velocity, and the equivalence ratio of reactant. Increasing the inlet velocity leads to a decrease in the total pressure gain of the RRDE. Once the inlet velocity exceeds the critical value, the engine cannot achieve positive total pressure gain. Increasing the rim velocity can improve the total pressure gain and the thermodynamic cycle efficiency of RRDE. Increasing the equivalence ratio can also improve the thermodynamic cycle efficiency and enhance the total pressure gain at lower inlet velocities. While at higher inlet velocities, increasing the equivalence ratio may reduce the total pressure gain. Numerical simulations are also performed to analyze the detailed flow field structure in RRDE and its variations with the inlet parameters. The simulation results demonstrate that the detonation wave can stably stand in the RRDE and can adapt to the change of the inlet equivalence ratio within a certain range. This study provides the preliminary theoretical basis and design reference for the RRDE.