Progress in Aerospace Sciences最新文献

A review of research progress in the design of the exhaust system for the scramjet and turbine based combined cycle (TBCC) engine is presented. Firstly, the technical challenges encountered in designing the exhaust system for a hypersonic propulsion system are highlighted and discussed, and the performance parameter definition as well as the theoretical thrust prediction for the exhaust system is introduced. The review of scramjet nozzle focuses on three aspects: 1) the design method of the single expansion ramp nozzle (SERN) for the integration of the airframe with the propulsion system, in which the design method developments of the two-dimensional (2D) SERN, SERN with lateral expansion and three-dimensional (3D) SERN with shape transition are all summarized; 2) the unique flow phenomena of the scramjet nozzle, including the nonuniform inflow and chemical nonequilibrium flow in SERN; 3) the coupling and interaction of the internal flow with the external freestream. Besides, the design and flow researches of the TBCC exhaust system is also reviewed for three parts: 1) variable geometry design for wide flight range, in which both a 2D and 3D exhaust system are described; 2) the overexpanded flow separation mechanism and its control at low flight Mach number; 3) mode transition from low-speed flowpath (LSF) to high-speed flowpath (HSF) for over-under exhaust system. Through the above summary and analysis, the current status, bottlenecks, and development trend of the exhaust system for an airbreathing hypersonic propulsion system can be further clarified.

The vast majority of shock wave–boundary-layer interactions in practical applications like supersonic aircraft intakes are three dimensional in nature. The complex behaviour of such interactions can generally be understood by combining the flow physics of a limited number of canonical cases. The physical understanding of these flow fields developed by numerous investigators over the last half century is reviewed, focusing predominantly on steady aspects of turbulent, uncontrolled interactions in the transonic and supersonic regimes, i.e. for Mach number less than 5. Key physical features of the flow fields and recent developments are described for swept compression corners, various fin interactions, semi-cones, vertical cylinder-induced interactions, swept oblique shock reflections and flared cylinders. In addition to the canonical geometries, a different type of three dimensionality concerning sidewall effects in duct flows, like intakes or propulsion systems, is also reviewed. The underlying mechanisms, centred on pressure waves propagating from the corner regions, are introduced and the implications for separation unsteadiness and flow control are discussed.

From the perspective of aeronautical engineers, this paper gives a systematical summary of the technical aspects of bird flight that should be considered in the analysis and design of flapping unmanned and micro air vehicles (UAVs and MAVs). The relevant aspects include the scaling laws, avian wing geometry, avian wing kinematics, aerodynamics models, computations, and special topics. Instead of extensively and uniformly reviewing a wide range of materials studied by avian biologists, we focus on the analytical and semi-analytical models and quantitative data as the useful guidelines for the design of flapping UAVs and MAVs.

This comprehensive study delves into the significance of asteroid research and proposes a systematic classification consisting of seven distinct categories. Initially, a concise definition is presented to differentiate between asteroids, meteorites, and comets, accompanied by a brief exploration of their unique characteristics. Recognizing the valuable scientific insights that these celestial bodies hold, the reasons for studying asteroids are categorized as follows: 1) Life's origin, 2) The Moon's origin, 3) The origin of water on Earth, 4) Vast reservoirs of valuable resources, 5) Colonization, 6) Threats, and 7) Advancing our understanding of physics. This paper meticulously reviews these seven reasons and subsequently delves into the achievements of past missions to low-gravity bodies, including Pioneer 10, Galileo, Clementine, NEAR Shoemaker, Deep Space 1, Cassini–Huygens, Stardust, Hayabusa, New Horizons, Rosetta, Dawn, Change 2, Hayabusa2, Lucy, Dart, and OSIRIS-REx. Additionally, future missions are introduced, while the challenges associated with flybys, mining operations, and asteroid landings are thoroughly examined.

Hierarchical structures provide a means to systematically deconstruct an engineering system of arbitrary complexity into its subsystems, components, and physical processes. Model validation hierarchies can aid in understanding the coupling and interaction of subsystems and components, as well as improve the understanding of how simulation models are used to design and optimize the engineering system of interest. The upper tiers of the hierarchy address systems and subsystems architecture decompositions, while the lower tiers address physical processes that are both coupled and uncoupled. Recent work connects these two general sections of the hierarchy through a transition tier, which blends the focus of system functionality and physics modeling activities. This work also includes a general methodology for how a model validation hierarchy can be constructed for any type of engineering system in any operating environment, e.g., land, air, sea, or space. We review previous work on the construction and use of model validation hierarchies in not only the field of aerospace systems, but also from commercial nuclear power plant systems. Then an example of a detailed model validation hierarchy is constructed and discussed for a surface-to-air missile defense system with an emphasis on the missile subsystems.

In recent years, the realm of space exploration has undergone a transformative shift, marked by the emergence of a thriving new space economy. This evolution has not only redefined existing space infrastructures and services but has also democratized access to space, accelerating exploration endeavors. At the core of such evolution is additive manufacturing (AM), a groundbreaking technology that has fundamentally altered the landscape of designing and producing launchers and space systems. AM not only enhances the efficiency of existing space missions but also unlocks novel avenues for space exploration and the establishment of sustainable human settlements beyond Earth. This paper provides a comprehensive and current exploration of the industrial catalysts driving AM adoption across key space domains. It delves into existing applications and uncharted frontiers, exploring innovative advancements while spotlighting industry gaps and obstacles. Motivated by the maturation of AM technologies, the proven track record of additively manufactured components in space missions, and the surge in research and investments aligning with major space market trends, this paper aims to provide aerospace and manufacturing communities with a panoramic view of present and future opportunities for AM within the rapidly expanding new space economy. Additionally, it sheds light on the profound impact and momentum gathering in this field, all the while examining the significant challenges that demand concerted attention.

Advanced Air Mobility (AAM) represents a collaborative vision shared by NASA, regulatory agencies, and global industry leaders, aimed at establishing a robust and reliable air transportation ecosystem, which is expected to facilitate safe and efficient movement of both people and cargo within urban, suburban, and regional environments. This paper presents a holistic review and analysis encompassing various aircraft designs, including different propulsion system designs and architectures (electric, hybrid electric, turboelectric, etc.), for different AAM aircraft applications, and state-of-the-art air traffic management, cybersecurity, and infrastructure strategies. Recent academic and industry literature on these aspects is critically reviewed and summarized, and a compilation of the aircraft models currently in development is also provided. The aircraft designs are categorized into a set of core groups, which include lift + cruise, tilt-wing, tiltrotor, multirotor, and rotorcraft, to analyze the existing literature systematically. For each of these core groups, literature on different propulsion system designs and architectures is reviewed and analyzed. Next, these core groups, including their variations based on propulsion system designs and architectures, are analyzed through a set of evaluation lenses. This provides a comprehensive insight into their respective strengths, weakness, and gaps in design considerations. The identified lenses include range and payload, performance, environmental impact, feasibility, traffic and infrastructure, noise, vehicle safety, and cybersecurity. Finally, directions for future research in AAM aircraft and overall ecosystem development are identified. In general, a more in-depth, quantitative analysis on the various evaluation lenses identified in this study and appropriate consideration to all these evaluation lenses at the design and development stage are highly recommended. This type of holistic approach will drive AAM aircraft designs towards convergence and help build an efficient, affordable, and sustainable AAM ecosystem.

The main goal of this paper is to present a vision for the future of aviation. Developing such a vision is always a complex matter, but in times of environmental emergencies and unjustifiable wars it becomes even more difficult. One of the main reasons of this paper is to show that there is still room for advancing clean technology developments and to demonstrate that the aviation sector is ready for embarking on new challenge.

Green and environmentally sustainable aviation, in our opinion, can be achieved with continuous improvements along multiple parallel paths, ramp up of SAF (Sustainable Aviation Fuel) production, and of course, breakthrough technologies. The latter will require a significant amount of research, testing and probably mistakes need to be made before reaching the level of transportation efficiency and mission safety obtained with traditional propulsion, but these drawbacks should only encourage scientists, engineers, politicians and visionaries to strongly pursue the objectives of a new eco-aviation.

Aviation decarbonization requires a strategy change from near term improvements in aircraft fuel efficiency to long term (from neutral to zero carbon emissions) fuel switching. The successful introduction of long-term solutions requires transdisciplinary research into technological, operational and economy fields.

New technologies should probably be introduced into smaller aircraft segments first then migrate into the larger segments as the technologies mature. We should expect a first electric and hydrogen fuel cell commuter aircraft entry into service by the end of this decade, with hydrogen combustion-powered narrow bodies around 2040.

In 2019, aviation accounted for approximately 2.3% of global greenhouse gas emissions, with global commercial fleet CO₂ emissions totaling 0.918 Gigatonnes. Narrowbody and widebody aircraft produce over 95% of the industry's greenhouse gas emissions, therefore, while the introduction of new technologies on smaller aircraft will be important for the development of sustainable solutions, they will have minimal impact on the overall carbon footprint until they make their way onto larger platforms. However, carbon-free fueled (electric, hydrogen) aircraft will require significant infrastructure investments to develop the novel transportation network and the re-fueling procedures that will be required to support their use. Therefore, their success will require the coordinated combined efforts of the entire industry (airlines, airports, air navigation service providers, manufacturers) and significant government support.

This paper tries to summarize the most important aspects for a vision on sustainable green aviation and to indicate a possible roadmap for reaching this goal.

Sustainability has recently been identified as the greatest challenge facing the modern aviation field. Given the extreme power and energy characteristics of transport-class aircraft today,achieving sustainability goals across the aviation sector is a tremendous challenge when compared to other modes of transportation. Several key energy carriers have emerged, promising an environmentally sustainable aviation future. Those considered here include bio-jet fuel pathways for synthetic kerosene, power-to-liquid pathways for synthetic kerosene, liquid hydrogen, ammonia, liquid natural gas, ethanol, methanol, and battery electric systems, all of which are compared to conventional fossil-derived aviation turbine fuel. However, these alternate energy carriers bring forward significant technoeconomic considerations that must be addressed before such approaches can be viably implemented. These factors include material properties impacting aircraft performance and fuel handling, emissions, cost and scalability, resource and land requirements, and social impacts. The purpose of this review is to provide a summary of current approaches to alternative aviation energy carriers, which includes a discussion of key advantages, challenges, and implications determining the future viability of each approach. It is found that bio-jet fuels, power-to-liquid synthetic kerosene, liquid natural gas, and liquid hydrogen all have technical feasibility and can contribute to improved environmental outcomes. However, hydrocarbon fuels and non-renewable production pathways for carbon-free energy carriers are not viable permanent solutions for a fully sustainable aviation ecosystem. As a result, potential transition scenarios from fossil-derived aviation turbine fuel to synthetic kerosene, with simultaneous development for adoption of liquid hydrogen and battery-electric systems, are recommended.