Rocket-based Combined Cycle Propulsion Research Articles

A survey on the conceptual design of hypersonic aircraft powered by RBCC engine

Rocket-based combined-cycle (RBCC) powered vehicles have been widely recognized as the most promising aircraft solution that could dramatically reduce the cost of space transportation. Researchers and scientists worldwide have conducted considerable overall design researches to cope with the challenges in RBCC development including mode transition, thermal protection and thrust enhancement. According to the way to orbit and the configuration characteristics, the hypersonic aircraft powered by RBCC engine are classified as four categories: single-stage-to-orbit (SSTO) two-dimensional configuration, SSTO axisymmetric configuration, two-stage-to-orbit (TSTO) two-dimensional configuration, and TSTO axisymmetric configuration. This paper systematically presents the development of the conceptual design of RBCC-powered vehicles. Both the structural and operating key parameters like the weight distribution, the RBCC propulsion performance and take-off mode, et al. are introduced in detail. On this basis, a comparative analysis of the advantages and disadvantages of the orbit model, the configuration selection and takeoff modes are conducted. In addition, the application prospect and technology development direction for hypersonic aircraft are also discussed. At the same time, the lessons that can be drew from previous hypersonic vehicle concept design are explored.

Research and development on inlets for rocket based combined cycle engines

Rocket based combined cycle (RBCC) engine is regarded as one of the most efficient propulsion systems for reusable space transportation vehicles and hypersonic cruise vehicles. It can perform excellently over a very broad range of Mach numbers and flight altitudes through multi-mode operations by effectively integrating high thrust-to-weight ratio of the rocket engine and high specific impulse of the airbreathing engine. The RBCC inlet, commonly operating in an extremely wide flight speed range covering static, subsonic, transonic, supersonic, and hypersonic, plays a vital role in the RBCC propulsion system and flight vehicles. This paper presents a comprehensive and systematical review of the research progress on the inlets for RBCC engines in different countries and different historical periods. A number of key technical and scientific issues specially concerning RBCC inlets are sorted out, including the wide range RBCC inlet design and optimization, inlet/embedded rocket/combustor matching and control, dynamic operation, etc. Several typical RBCC inlet applications and the corresponding research are discussed, including the Strutjet inlet, A5 inlet, GTX inlet, and the Astrox's inlet in the U.S., the RBCC inlet in JAXA, and a sidewall compression RBCC inlet in China. Finally, experience gained and some recommendations are summarized for future research of the RBCC inlet.

An analysis tool of the rocket-based combined cycle engine and its application in the two-stage-to-orbit mission

The rocket-based combined cycle (RBCC) engine is believed to be an ideal propulsion system for the space round trip mission in the future. The mission planning process is limited because there is no available performance data on the RBCC engine. This paper proposed a thermodynamic analysis tool of the RBCC engine. Working over a wide speed range, this tool divides the engine’s working process into four modes, namely the ejector, the ramjet, the scramjet and the pure rocket modes. The results are validated by data in the previously published literatures. Based on this tool, the equal-dynamic pressure trajectory analysis is implemented for the first stage of a two-stage-to-orbit vehicle equipped with an RBCC propulsion system. The influences of the launch weight and the engine size of the vehicle on the acceleration performance are studied. The dynamic pressure of the designed trajectory is also in the scope of this work. The results show that a lighter launch weight, a larger engine size and a larger designed dynamic pressure are positive for the fast acceleration process with lower fuel consumption. In addition, a long distance transportation mission requires different design conditions with that in the fast acceleration mission.

Climbing performance analysis of rocket-based combined cycle engine powered aircraft

Evaluating the climbing performance of rocket-based combined cycle (RBCC) powered aircraft has a guiding role for single-stage to orbit. This study establishes a new modularized thrust model of the RBCC engine for low speeds (Ma∞ = 0.8–3) based on independent ramjet stream and pressure matching. The model can quickly estimate the quasi one-dimensional flow characteristics of secondary flow and primary flow at given runner geometry and operating conditions. Comparison with experimental results shows that the thrust model is correct. In this model, the influence of altitude, Mach number, and rocket flow on thrust and specific impulse is considered. The model was used to optimize the climbing trajectory of RBCC powered aircraft with a typical lifting-body. The comparison of RBCC propulsion and pure rocket propulsion shows that the former offers propellant saving advantages. During the climb, the RBCC powered aircraft needs to strictly control the air flow rate and ensure the pressure matching in the flow path to improve propulsion efficiency.

Investigation on Effective Sampling Strategy for Multi-objective Design Optimization of RBCC Propulsion Systems via Surrogate-assisted Evolutionary Algorithms

Rocket-based combined cycle (RBCC) engines are an airbreathing propulsion technology that offers considerable potential for efficient access-to-space. Successful design of RBCC-powered space transport systems requires reliable databases for both vehicle and engine performance, calling for an effective sampling method to accurately resolve non-linear characteristics in vast design space. This paper presents an optimal sampling strategy based on the function gradients to realize efficient database construction based on evolutionary algorithms and assesses its effectiveness by applying the methodology to various test functions with multiple objectives as well as surrogate models representing scramjet intake characteristics for validation.

Combined Rocket and Airbreathing Propulsion Systems for Space-Launch Applications

A review of rocket-airbreathing combined-cycle propulsion systems for Earth-to-orbit applications is presented. Rocket-based combined-cycle (RBCC) engines take advantage of the synergistic interactions between the rocket and the airbreathing elements of the engine and the use of high-specie c impulse cycles to yield a mission-averaged specie c impulse that is higher than all-rocket technology can provide. An overview of the multimode operation is given, along with a review of both experimental and modeling work that has been done on this class of engines. Selected issues involved with these engines are discussed. These include engine/vehicle integration, e ow-path design for multimode operation, fuel selection, mixing enhancement and afterburning in rocket-ejector mode, thermal choking, and e ameholding. RBCC propulsion is becoming recognized as a promising technology for achieving a signie cant reduction in the cost of delivering payload to orbit.