Combined cycle propulsion combines two or more single types of power organically, with integrate each other in structure and complements each other in function, greatly expanding flight envelope and improving flight efficiency. It has important applications in near space hypersonic vehicle, reusable space transportation system and other fields. This paper introduces the basic classification and working principle of combined cycle propulsion, reviews the application of combined cycle propulsion technology in near space hypersonic vehicle and reusable space transportation system, and summarizes the development trend and main key technologies of combined cycle propulsion vehicle.

The horizontal take-off and horizontal landing (HTHL) aerospace vehicle is an important means for future space rapid response and low-cost space transportation. Combined cycle power has full envelope flight capability, and uses air as an oxidant in the atmosphere to greatly enhance the specific impulse of the engine. Therefore, it is the preferred engine system for future HTHL aerospace vehicle. This paper reviews the development history and status of the combined cycle powered aerospace vehicles at home and abroad, and describes the advantages and disadvantages of various types of takeoff and landing. The advantages of HTHL and the requirements for the vehicle and engine are clarified. By comparison of RBCC and rocket for aerospace vehicle, the application advantage of combined cycle engine in HTHL aerospace vehicle is confirmed.

Combined cycle propulsion technology is an organic combination of multiple propulsion technologies from the aspects of thermal cycle, structural configuration and so on, which has the characteristics of wide flight envelope and better comprehensive performance. In this paper we summarize the development history of foreign combined cycle engines, then introduce several mainstream typical combined cycle engines. We also discuss and summarize the development trend and key technologies of combined cycle propulsion technology. Finally we propose some suggestions for technology development.

Reuse is a promising technology for launch vehicles. Rocket based combined cycle(RBCC) propulsion system is a good choice for reusable launch vehicles. In this article the development status of RBCC engine and key technological issues are described, possible application areas, and development path are analyzed as well. To make full use of the advantages of ramjet and rocket engine and remedy function disfigurement and performance deficiency of LRE(改为全称) or ramjet distinguishes RBCC engine from other power engines. On the basis of current technologies, the RBCC engine solution formed by different working modals and engine configurations is the developmental route of RBCC power system to meet the needs of fly mission.

Turbine based combined cycle engine will be the main power device of future hypersonic aircraft. It can meet the requirements of space transportation, high-speed transportation and long-distance rapid strike. It has the advantages of conventional take-off and landing, repeated uses and good economy. This paper reviews the development of key technologies of turbine-based combined cycle power in many aviation powers, and analyzes the key technical bottlenecks that must be solved in the research of turbine based combined cycle engine technology including mode transition, aircraft and engine integration, ultrawide operating range, high temperature resistance, compatibility and so on. Combined with the advanced experience of foreign countries, the paper expounds the development prospects and suggestions of domestic turbine based combined cycle engine research, and summarizes the key technical problems of turbine based combined cycle engines that must be solved.

Based on an analysis of the characteristics of pre-cooled air-breathing combined engine, the research progress of five types of engines in the world are summarized. Key techniques, advantages and disadvantages of the engines are also analyzed and discussed. Finally a proposal for future development of the engine is presented.

The history of hypersonic propulsion facilities and tasks are briefly reviewed in this paper, the operating principle, main structures and basic parameters of these reclassified facilities are also surveyed, including direct-connect supersonic combustion test facility, combustion-heated high temperature tunnel, arc-heated scramjet test facility, high enthalpy shockwave facility and combustion-heated impulse tunnel. After an analysis of the characteristics of different facilities, it is pointed out that the combustion-heated impulse tunnel is the ideal facility for aero-propulsion integration test.

In this paper, thermal management technologies for hypersonic flight vehicles are reviewed from the point view of heat dissipation and reuse. For heat dissipation, concepts concerning such as passive/semi-active/active thermal protection, structure/thermal integrated protection, and other multi-functions are reviewed. For heat reuse, some regenerative cooling and thermoelectric conversion technologies are also reviewed. Finally, based on the characteristics and research progress of aforementioned technologies, some potential research fields of thermal management for hypersonic flight vehicles are proposed.

To meet the needs of new space vehicles in the future, the combined power engine emerges timely. This paper introduces the main types and working principles of the combined power system, makes a preliminary analysis of the research progress and management mode of the typical combined power vehicle technology project in the United States, and puts forward some relevant measures and suggestions based on the military and civilian integration strategy in China.