Hypersonic Aerothermodynamics

For most re-entry capsules, the shape of the forebody of the capsule is designed based on the blunted nose cone. A similar shape can be created using a hyperboloid of revolution that can control the nose bluntness and the half angle of the cone easily. In this study, the hypersonic aerodynamic characteristics of re-entry capsules designed with hyperbolic contours were investigated using the CFD code, FaSTAR, developed by Japan Aerospace Exploration Agency (JAXA). The CFD results showed that, using the hyperbolic contours, the drag and lift coefficients can be increased compared to those for the Hayabusa re-entry capsule without changing the shape of the capsule drastically. This suggests that shape design based on the hyperbolic contours can improve the aerodynamic characteristics of re-entry capsules.

HE shock-shock phenomena occurring at supersonic and hypersonic flows present critical challenges in the design of supersonic and hypersonic vehicles. Aerodynamic heating and increased pressure loads are two such challenges as highlighted in the cases of the X-15 ...

Smart structures sense external stimuli, process the sensed information, and respond with active control to the stimuli in real or near-real time. The response to external stimuli can be through deforming or deflecting the structure, or through communicating the sensed information to another control center. Smart materials enact a deformation or deflection of the structure by changing their physical properties when subject to either an electric, magnetic or thermal load. Multifunctional structures (MFS), in addition to supporting loads, incorporate sensors to detect and evaluate loads or failure, and to interact with the surrounding electromagnetic environment. MFS represent a new manufacturing and integration technology by which communications and electronics equipment are integrated into conformal load-bearing structures. The technology is enabled by advances in large-scale integrated electronics packaging, lightweight composite structures and high-conductivity materials. In multifunctional structures, electronic assemblies (multichip modules), miniature sensors and actuators are embedded into load-carrying structures, along with associated cabling for power and data transmission. This level of integration effectively eliminates traditional boards, boxes, large connectors, bulky cables, and thermal base plates, thereby yielding major weight, volume and cost savings, over traditional structural and electronic packaging techniques. The Aeronautics Enterprise works closely with it customers and partners to ensure that its technology, products and services are developed to levels where customers can confidently make decisions regarding the application of those technologies. This strategy allows the enterprise to support the national aeronautics goals: Maintain the superiority of U.S. aircraft and engines; Improve safety, efficiency and affordability of the global air transportation system; Ensure the long-term environmental compatibility of the aviation system; and Achieve aircraft-like operations and costs for launch systems. Research programs are in place to develop technology that provides benefits in the following areas: Performance a Efficiency and affordability Survivability Safety and security Capacity and efficiency Environment, and Cost per pound to place payload into low-earth orbit. System Benefit Framework for the National Goals National Goals Maintain the S ' ' of U.S. Aircraft an NASA R&T BASE LEAD ROLES To take advantage of the unique capabilities that exist at each of the research centers, the Aeronautics Research and ~e c h n o l o ~~ Base consists of six programs: Airframe Systems Aviation Operations Systems Flight Research Information Technology Propulsion Systems, and Rotorcraft. Each element is led where the center of gravity of relevant expertise exists. The Airframe Systems Program is led at Langley Research Center. Airframe systems are those systems that determine or characterize the performance of an aircraft, including airframe-propulsion system integration. Key elements of airframe systems include the following: Conceptual design Aerodynamic design, development, and testing Structural design, development, and testing (including airframe materials) Flight crew station design, integration, and testing, and Airborne systems (including flight mechanics, controls, electromagnetics, and flight-crucial systems) design, integration, and testing. The Agency Center of Excellence for Structures and Materials, one of the key elements of airframe systems, is located at Langley Research Center. ASP0 LEVEL-HI PROGUMS Airframe systems technology development for some specific vehicle classes are addressed in other Aeronautics Enterprise programs. The Advanced Subsonic Technology (AST) Program has focused technology efforts for general aviation, civil tiltrotor, and subsonic transport aircraft. In addition, Ames Research Center leads the Research and Technology Base portion of the Rotorcraft Research Program. The High-Speed Research (HSR) Program is developing technologies that will allow the decision on the feasibility of building an economically viable supersonic civil transport aircraft. Reusable launch vehicle (WV) technology is being developed in the X-33 Program. While technology developments in the focused programs are aimed at relatively nearterm applications, the Airframe Systems Program has the following characteristics: Breakthrough technologies High-rismigh-payoff * Revolutionary Expanding Frontiers * Pioneering research for the twenty-first century Requires paradigm shifts A sound investment in America's aeronautics future, and Complemented by focused programs. The Airframe Systems Program Office (ASPO) has planned a set of innovative Level-I1 research programs that are focused along advanced conceptual (systems) studies, transport aircraft, high-performance aircraft, and fundamental aeronautical concepts and methods. These programs are shown in the figure. In order to assure that the research planning and implementation is responsive to customers' needs, the management of the Airframe Systems Program centers around vehicle classes and long-term aeronautics research needs. A Systems Studies and Analysis element provides independent assessments, high-payoff research and concepts, and data for deciding investment strategies. The Level-I1 programs are managed within the Aeronautics Systgms Analysis Division, the Civil Transportation Office, the High-Performance Aircraft Office, and the Fundamental Concepts and Methods Office. The Rotorcraft, Airspace Operations, and Information Systems managers serve as the Langley points of contact for those programs. The figure shows how the Airframe Systems Level-I1 programs align with the national goals. This slide presents a brief description of the following Level-I1 programs: Megaliner Error-Proof Flight and Aircraft Electronic Systems * Advanced Life Extension (ALEX) Integral Airframe Structures (L4S) Alternate Civil Capacity, Environment, Efficiency, and Safety Solutions (ACCESS), and Advanced Subsonic Transport Aircraft Research (ASTAR). This presentation contains details about the following programs: Megaliner ALEX * IAS. These programs involve a significant amount of structures research. Airframe Systems Programs v Revolutionary subsonic long-haul transports Error-Proof Error-Proof flight deck and mission critical systems Systems (Error-Proof) Advanced Life Airworthiness of thick, metallic structural Extension (ALEX) components typical of wing structure, in the aging commercial transport fleet Integral Airframe Low cost large, integral, metallic structures Structures (IAS) Alternate Civil Capacity, Cooperative activities with industry or other Environment, Efficiency, government agencies 81 Safety Solutions (ACCESS)

Conventional multi-layer insulations exhibit excellent insulation performance but they are limited to the temperature range to which their components reflective foils and spacer materials are compatible. For high temperature applications, the internal multi-screen insulation IMI has been developed that utilizes unique ceramic material technology to produce reflective screens with high temperature stability. For analytical insulation sizing a parametric material model is developed that includes the main contributors for heat flow which are radiation and conduction. The adaptation of model-parameters based on effective steady-state thermal conductivity measurements performed at NASA Langley Research Center (LaRC) allows for extrapolation to arbitrary stack configurations and temperature ranges beyond the ones that were covered in the conductivity measurements. Experimental validation of the parametric material model was performed during the thermal qualification test of the X-38 Chin-...

This study explores how surface temperature influences the critical Reynolds number and turbulence onset in the boundary layer over a flat plate. Using Computational Fluid Dynamics (CFD) simulations in ANSYS Fluent, the research examines the effects of varying surface temperatures (300 K, 350 K, 400 K, and 450 K) on fluid behaviour. The simulations model the interaction between flow dynamics and temperature-dependent fluid properties, such as viscosity and density, to determine how these changes impact flow stability. The results demonstrate that increasing surface temperature significantly lowers the critical Reynolds number, leading to an earlier transition from laminar to turbulent flow. This behaviour is validated through critical Reynolds number plots, skin friction coefficient profiles, and turbulence intensity contours, all of which show that higher temperatures destabilize the boundary layer and shift the transition point upstream. The findings are consistent with theoretical predictions and emphasize the destabilizing effect of temperatureinduced reductions in fluid viscosity. These insights have practical implications across fields such as aerospace engineering, where temperature control on surfaces can optimize aerodynamic performance and fuel efficiency, and HVAC systems, where turbulence management can improve energy efficiency. While the study uses a simplified 2D flat plate model, it provides a strong foundation for understanding temperature-turbulence relationships. Future research could extend these findings by exploring more complex 3D geometries, surface roughness, and different flow conditions to further refine turbulence control strategies.

This NRC Decadal Survey white paper, provided by the thermal protection technology community, is a general assessment of the current capability of thermal protection systems (TPS) with respect to the scientific exploration of Venus as well as anticipated TPS requirements in support of future Venus missions 1,3,5. The paper begins with a brief history of

A comprehensive state-to-state (StS) model for air was formed -including vibrationvibration-translation (VVT) reactions. The generated VVT reaction rates were compared to available first principles calculations and reasonable agreement was obtained. The influence of multi-quantum transitions revealed that the possible reduction on the number of VVT transitions depends on the application. The influence of VV transitions revealed that the vibrational excitation becomes too fast if VVT transitions are reduced to VT transitions, invalidating this approximation. Comparisons were made with existing NO emission measurements in the UV and mid-IR spectrum. At velocities of 3 -4 km/s, some of the current O2 dissociation rates may be inaccurate. At a higher velocity of 6.81 km/s, the NO mole fraction predicted by the StS model is around an order of magnitude greater than that predicted by the two-temperature model. Finally, recommendations were given on the further development of the state-to-state model.

A multistage system has been proposed for cooling a circulating fluid that is subject to intermittent intense heating. The system would be both flexible and redundant in that it could operate in a basic passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a second cooling subsystem that could be active, passive, or a combination of both. This flexibility and redundancy, in combination with the passive nature of at least one of the modes of operation, would make the system more reliable, relative to a conventional cooling system. The system would include a tube-in-shell heat exchanger, within which the space between the tubes would be filled with a phase-change material (PCM). The circulating hot fluid would flow along the tubes in the heat exchanger. In the basic passive mode of operation, heat would be conducted from the hot fluid into the PCM, wherein the heat would be stored tempora...

are gratefully acknowledged • The team also thanks Prof. Bruce Fegley, Jr. (Washington U., St. Louis) for discussions & references on silicate chemistry • We thank Prof. Peter Brown (U. Western Ontario), Prof. Jay Melosh (Purdue), & Dr. Olga Popova (Russian Academy of Sciences) for informative seminars • We thank line managers (ERC, Inc. & TS Division) for their support • ERC, Inc. was funded by NASA contract NNA10DE12C 7/7/2015 Entry Capsules vs Meteors Capsule (Earth entry) Meteoroid (Asteroid) Shape Regular and smooth geometry Irregular and rough geometry Material Manufactured ablative material Depends on asteroid class (S, M, X) Structure Minimal voids and cracks; Known structural properties Could have voids & could be fractured; Structural properties of meteorites Shape Change Negligible recession/mass loss Recession dominated Fragmentation Not an option! S-class most likely to fragment 7/7/2015 Although meteor physics has some things in common with capsule entry physics, the approaches to the problem are different-reconstruction vs prediction Capsule (Earth entry) Meteoroid (Asteroid) Validation Data Sensors, imaging, capsule recovery Light curves, infrasound, falls Ground Testing Ballistic ranges, arc jets, wind tunnels, laser facilities Probably same facilities as capsules, but with limitations Recovered Stardust Capsule Recovered Chelyabinsk Meteorite

One of the major challenges for researchers in hypersonic flow is to reduce and optimize the drag that occurs when a body is in continuous interaction with fluids. The effects of drag are relatively lower when the body is moving at slower speeds but as the relative motion between the fluid and the body increases, the drag and heat generation increases rapidly. Geometrical modifications are one of the ways to reduce the drag on the afterbody in hypersonic flow. In this paper a series of numerical simulations are carried out on a 2-D axisymmetric model of a blunt module. The stepped, conical, cylindrical and end cavity after bodies are simulated and their drag values are evaluated and compared. Finally, this paper will help the researchers to study the effect of drag on different geometries and optimally choose the best suited geometry according to their requirements.

Проведено прямое численное моделирование развития турбулентных пятен в пограничном слое на плоской пластине под нулевым углом атаки при числе Маха набегающего потока $\mathrm{M}_\infty=6$. Рассмотрено распространение искусственно возбуждeнных локализованных трeхмерных вихревых возмущений с различными начальными амплитудами, которые при распространении вниз по потоку развиваются в турбулентные пятна. Моделирование выполнено в рамках решения уравнений Навье--Стокса для пространственных течений сжимаемого газа с помощью авторского расчeтного кода, реализующего неявный метод сквозного счeта. Показано, что универсальная квазимонотонная численная схема позволяет корректно оценивать основные характеристики турбулентных пятен - угол поперечного раскрытия и скорости переднего и заднего фронтов. Продемонстрировано согласование полученных параметров пятен с результатами других авторов.

: In many engineering applications involving fluid-thermal systems, detailed quantitative information on the flow, temperature, and species concentration is needed for system optimization. Numerical simulation can obtain the desired information and thus optimize the system. However, this approach requires well-defined boundary and operating conditions which may not be completely known due to limited access for experimental measurements. The objective of our research is to develop a Dynamic Data Driven Applications System approach that synergizes experiment and simulation to determine the boundary and operating conditions, thereby achieving a full simulation capability. Regarding the heated wall jet in the crossflow problem, the objective is to determine the met inflow conditions using a Dynamic Data Driven Applications Systems method that synergizes experiment and simulation.

This paper addresses the question of whether humans will ever be able to settle space in an economically sustainable way and, if there is still hope of this, where the greatest hope may lie. It reviews key developments of the last 40 years relevant to this issue, such the space shuttle, the National Aerospace Plane, the Russian Ajax effort, nonlinear control challenges, challenges of developing a "skin" to withstand re--entry, current space programs around the world, and key markets for using such vehicles, such as energy from space and space manufacturing. Very powerful new mathematical tools have been developed, and are still being developed, which could play a crucial role in allowing humans to achieve economically sustainable settlement of outer space. [1--5]. Unfortunately, the global dynamics of science and technology as a cultural system are coupled with larger economic and political dynamics all over the earth, in such a way that the probability of humans moving out in a permanent, serious way into space now seems only slightly larger than the probability of monkeys learning to fly on their own. There is still some hope, logically. It is not rational to give up hope when it is a matter of survival of an important endangered species (humans), but all the remaining hope requires some understanding of the larger situation. I would like to express my thanks to Dr. Kuzmina for asking me to give some reminiscences on the progress and challenges which I have been part of here. Of course, the hope for humans to settle space in a sustainable, permanent way goes back to people long before I was born. People who read this journal probably all know about Tsiolkovsky more than I do. Even in the USA, many people remember the words: 'The earth is the cradle of mankind, but we cannot live forever in the cradle." In the US, many people remember the vision of Kraft Ehricke , who said that the movement of humans into space would be a great moment in the history of life in this solar system, as important of the movement of the first ocean vertebrates up onto the land. Still, in considering this vision of Ehricke, a cartoon story has sometimes appeared in my mind. I see a beat--up talking fish in the ocean (a bit like myself in some ways) who is talking to the other fish. He says: "I have succeeded in the great ambition to visit that other world above us, to explore, and to learn what our true * The views herein are just my personal views. They do not represent the views of any of the organizations I have worked with or for. role in the universe really is. In that greater world, they call us sashimi…" Not exactly, but in order to be "rational" as defined by von Neumann and Morgenstern , it is important that we consider a wide range of alternative possible scenarios. This paper will discuss a lot of earlier history, precisely because of the pressing needs we have today. Most of the space policy makers today are on track to repeat the same kinds of mistakes they have made in the past, both at the political level and at the technical level. Only by learning the lessons of past mistakes could we have much hope at all for success in the future. I will discuss this from my personal viewpoint, because that is the original database I have to work with here. My own journeys into the human space program began in graduate school, in the early 1970's. Actually, I saw the first moon landing on TV in 1969, on a television in Ann Arbor, Michigan. In 1971, when I worked at the Bendix Office of National Security Studies, in Ann Arbor, data from the latest moon landings came right back from space to the computer I was using for my summer job. I remember this well, because the computer operators gave priority to the program I was developing myself. At that time, I had developed a concept later called "Granger causality," and was using it to disentangle the web of causation for variables describing the state of the war in Vietnam. My early papers on this concept were not published, because they were classified; however, on my 21 st birthday, in September 1971, they flew me to present the findings to the number 6 and number 3 people in the Pentagon (Thayer and Einthoven), and they had a major impact on the changes which extracted the US from that war. Back at Harvard that year, I learned of the then recent seminal NASA reports by George Mueller of the Goddard Space Flight Center (GSFC) in Greenbelt, Maryland [6]. Muller's reports demonstrated a level of careful analysis, vision and detail which was already more advanced than most of what I see in the space area today. He understood, intuitively, that the hopes for humans in space depend very directly on a key number: the cost of access to space, which I think of as "$/kg--LEO." Dollars per kilogram, for mass conveyed to Low Earth Orbit. Mueller showed that the actual fuel cost of getting to earth orbit is much, much lower than the cost we were paying for the Apollo program. He performed an in--depth analysis of the many sources of cost in traditional 1960's launch technology. Above all, he developed a comprehensive strategy for how to minimize that cost. He performed tradeoff studies for airplane--like reusable launch vehicles, two stage to orbit (TSTO) and single stage to orbit (SSTO). He also provided a concept of operations at airports, to minimize the cost. These NASA reports were widely available, and I read them in the Harvard library. Mueller's reports were exciting and electrifying to me, because of my own previous efforts to understand the dynamics of historical processes and the role of key technologies. I recognized immediately why this breakthrough would be crucial in opening up a viable new economic frontier in space , and in creating a new

The viability of a High-Speed Civil Transport, HSCT, is very dependent on its cruise aerodynamic performance. The nature of the flow over a supersonic configuration changes through out its operating flight regime from low speed take off and landing condition, through subsonic cruise, transonic acceleration to supersonic cruise. The aerodynamic performance characteristics as well as the effectiveness of the control surfaces can be very dependent on both Reynolds Number and the flight Mach number. The lack of understanding Reynolds numbers effects, together with the inability to test at full scale conditions plus the uncertainties in the adequacy of CFD predictions lead to a number of fundamental Reynolds Number related questions: • Are correct configuration decisions being made? • Are the correct high lift systems and control surfaces being developed? • When is testing at low Reynolds adequate? • When is testing at high Reynolds number required? • Can CFD codes, validated with low Reynolds number data, adequately predict forces, moments and flow characteristics at full-scale conditions? • Do errors between experiment and theory imply of incorrect representation of the flow physics? This paper will focus on the effects of Reynolds number on HSCT type configurations over the supersonic climb / cruise portions of the flight envelop. Many of the discussions and conclusions will apply equally to military type aircraft operation in a similar flight regime having similar geometric features. The general nature of possible types of surface flow, that a supersonic aircraft may encounter within its flight regime, will be summarized. Simplified flow analogies along with wind tunnel data and CFD computational results will be used to explore the dependency of the flow characteristics on specific geometric design features of an aircraft as well as upon Reynolds number. In the process, assessments will be made of the ability of the inviscid and Navier Stokes CFD methods to predict flow features, forces, moments and pressures at both wind tunnel and flight conditions.

The control of the flow gains importance due to the expected increasing fuel cost as well as environmental constraints. For the most aircrafts in service, the flow over the swept wings is turbulent in cruise conditions, partially due to the contamination experienced from the fuselage and partially due to given wing geometry configuration and flow conditions. In this paper several solutions for passive anti-contamination-devices (ACD) for laminar flow control, applicable for swept subsonic and supersonic wings are presented. The ACDs are capable to stop the spanwise propagation of fuselage-induced contaminated flow along the attachment line and to ensure the generation of a new laminar attachment line boundary layer. The first solution was originally developed for supersonic flow in the frame of the European Project SUPERTRAC, where it was also experimentally tested and proven to be effective. This solution is also suitable for existing aircrafts in service as “add-on” and it was ext...

Herein we present a numerical analysis of the drag force produced by the flow over a square cylinder with a flat plate positioned upstream thereof. The numerical model used to solve the comprenssible Navier-Stokes equations is based on a finite difference method, second order in time and fourth order in space. The plate height was varied from 20% to 100% the side of the square cylinder, and the distance between the plate and the cylinder was varied from 0.5 to 3.0 times the side of the cylinder. The Reynolds number was considered to be 650, based upon the side of the cylinder and the inflow speed. The numerical predictions show that, for some cases, the total drag force produced by the square cylinder and plate system is lower than that of the square cylinder only.

Wide Range Ramjets appear to be a good solution for propulsion of reusable space launchers. These airbreathing engines are able to work from Mach 2 to 6 with subsonic combustion and then with supersonic combustion from Mach 6 to Mach 12 (for example). It could be interesting to complete the Wide Range Ramjet operation with detonationbased cycles. AEROSPATIALE has now a good experience of actual size hydrogen fueled hypersonic ramjets, from the system point of view, the air intake design, the combustors tested in Bourges up to Mach 6,5, the CFD support, the testing and measurement technics (ground and flight test methodology) and the engine structural point of view, with close connection with the launcher designer. The intest CHAMOIS supersonic combustion ramjet is an example of this know-how. Moscow Aviation Institute (M .A. I .) propulsion specialists have been working since the sixties on hypersonic ramjets and scramjets. A lot of experiments have been performed, and the laboratory's engineers have an accurate understanding (including high level of mathematical modelization) of the phenomena occuring in such engines. The interactions with the air intake, the nozzle and the vehicle have also been taken into account. The M.A.I. materials laboratory has been associated to design, build and test the structures required for these engines. Three years of personal contacts and high level of cooperation have shown that the AEROSPATIALE and Moscow Aviation Institute multicomponent methodologies for hypersonic propulsion are similar but complementary. The main common features are the both analytical and experimental understanding, the systematic experimental validation of the thermodynamic and structural options for the engine, the interest on the Wide Range Ramjet for reusable space launchers.

The study of laminar, shock boundary layer interactions is performed using direct simulation Monte Carlo and linear stability theory for Edney type IV flows over a double wedge and a double cone. The high-fidelity time accurate simulations are shown to characterize the complex shock interactions of such flows as well as their unsteadiness. Comparison of bow shock oscillations and Kelvin-Helmholtz instabilities are found to be consistent with earlier values in the literature.

The performance of Advection Upstream Splitting Method AUSM schemes are evaluated against experimental flow fields at different Mach numbers and results are compared with experimental data of subsonic, supersonic and hypersonic flow fields. The turbulent model used here is SST model by Menter. The numerical predictions include lift coefficient, drag coefficient and pitching moment coefficient at different mach numbers and angle of attacks. This work describes a computational study undertaken to compute the Aerodynamic characteristics of different air vehicles configurations using a structured Navier-Stokes computational technique. The CFD code bases on the idea of upwind scheme for the convective (convective-moving) fluxes. CFD results for GLC305 airfoil and cone cylinder tail fined missile calculated on above mentioned turbulence model are compared with the available data. Wide ranges of Mach number from subsonic to hypersonic speeds are simulated and results are compared. When the...

An innovative type of pressure distribution for the hypersonic aircraft forebody (bump) is presented, and this design is based on the newly established known as pressure ridge (PR) flow mechanism. Studies on the low-kinetic-energy fluid over the aircraft surface are summarized. Then, the challenges of the inlet-airframe integration at high speeds are discussed. The flow structure around the bump is analyzed in detail to eliminate the side-embedded shock (SES) effect at the inlet entrance. The concept of PR is proposed to improve the overall aerodynamic characteristics of the bump, namely, the boundary layer removal, the reduction of external drag, and the streamline direction at bump end-section. On the basis of the developed inverse method to generate the bump surface by the prescribed pressure distribution, the improved PR-derived bump is designed and numerically compared with the typical pressure-controllable bump (PCB) while the identical leading edge profile is imposed. Results demonstrate that the PR creates outward and inward pressure gradients. The removed amount of boundary layer increases with the increase in outward pressure gradient. Meanwhile, the inward pressure gradient * = stagnation properties x = freestream direction y = height direction z = crosswise direction peak = peak value s = starting cross section of bump e = ending cross section of bump

This work is a computational study of a rarefied non-reacting hypersonic flow past a forward-facing step at zero-degree angle of attack in thermal non-equilibrium. Effects on the flow field structure and on the aerodynamic surface quantities due to changes in step frontal-face height are investigated by employing the direct simulation Monte Carlo method. The work focuses the attention of designers of hypersonic configurations on the fundamental parameter of surface discontinuity, which can have an important impact on even initial design. The results presented highlight the sensitivity of the primary flow field properties, velocity, density, pressure and temperature, to changes in the step frontal-face height. In addition, the behaviour of heat transfer, pressure and skin friction coefficients with variation of the step frontal-face height is detailed. The analysis shows that hypersonic flow past a forward-facing step in the transition flow regime is characterized by a strong compression ahead of the frontal face, which influences the aerodynamic surface properties upstream and adjacent to the frontal face. The analysis also shows that the extension of the upstream disturbance depends on the step frontal-face height. It was found that the recirculation region ahead of the step is also a function of the frontal-face height. A sequence of Moffatt eddies of decreasing size and intensity is observed in the concave step corner. Locally high heating and pressure loads were observed at three locations along the surface, i.e. on the lower surface, on the frontal face and on the upper surface. The results showed that both loads rely on the frontal-face height. The peak values for the heat transfer coefficient on the frontal-face surface were at least one order of magnitude larger than the maximum value observed for a smooth surface, i.e. a flat plate without a step. A comparison of the present simulation results with numerical and experimental data showed close agreement concerning the wall pressure acting on the step surface.

The SCDI (Satelite de Coleta de Dados I) is a spin stabilized low-Earth orbit satellite dedicated to the collection and distribution of environmental data. It was completely developed at the Brazilian Institute for Space Research (INPE) and is scheduled to be launched in 1992. The SCDI passive thermal control design configuration is presented and the thermal analysis results are compared with the temperatures obtained from a Thermal Balance Test. The correlation between the analytical and experimental results is considered very good. Numerical flight simulations show that the thermal control design can keep all the subsystem temperatures within their specified temperature range.

The principle objective of this design competition is to provide upper-level students with an opportunity to integrate the use of engineering measurements and analytical modeling techniques to accurately predict a priori the performance of a miniature rocket system. A secondary objective is to provide these students an opportunity practice and improve communication, leadership, and technical skills while grouped in small competing teams. Each engineering team is challenged to predict the performance of a miniature rocket by developing an analytical model of the rocket trajectory using engineering principles and laboratory measurements. The student teams also participate in the hands-on activity of building and launching the prototype rocket system. This prototype is ultimately used to test the predictions of the analytical model. It is launched for the first, and last, time as the concluding event of this design competition. To add realism to the activity, the student teams are given imitation money that is used to buy the materials (e.g. the rocket) and services (e.g. wind tunnel time). Points are awarded based on the analytical model, the results from the component testing, the aesthetics of the rocket, the weight of the finished rocket, the costs of the project, and finally, the performance of the r ocket. This design competition provides the students with an open-ended design problem that emphasized the importance of employing the engineering design process in the development of a functioning prototype.

Many studies have forecast the development of hypersonic flight systems to meet future military and commercial needs while some systems are already in the early development and testing stages. Systems have been envisioned for space launch, fastreaction, global-reach strike and reconnaissance, tactical weapons and missile defense, for example. Before extensive flight testing is undertaken during the acquisition process, these systems will require ground testing, and evaluation capabilities which far exceed those available today. Requirements are anticipated for flight duplication testing at Mach numbers in the range from 8 to 20 at relatively high flight dynamic pressures to adequately support the full range of system development and acquisition programs. It is critical to duplicate the hypersonic flight environment in terms of pressure, temperature, velocity, and air chemistry at nearly full scale for airbreathing propulsion, because of non-scalable combustion processes involved, as well as for jet interaction and aero-optics testing. Ground testing facilities do not currently exist in the U.S. to perform adequate development and qualification testing at the necessary atmospheric flight simulation conditions above Mach 4, and technologies are not available for building adequate test facilities above about Mach 7. Conventional ground testing techniques utilize electric arcs, combustion heating or compression heating of the test gas in a stagnation chamber before the gas is expanded through a nozzle throat to the desired test conditions. These techniques involve serious deficiencies in test duration, gas composition, or gas thermodynamic conditions (velocity, pressure, and/or temperature). For any of * The research reported herein was performed by the Arnold Engineering Development Center (AEDC), Air Force Materiel Command. Work and analysis for this research were performed by personnel of Sverdrup Technology, Inc., AEDC Group, technical services contractor for AEDC. Further reproduction is authorized to satisfy needs of the U. S. Government. " Senior Member, AIAA.

This paper presents the design logic of the USV3, an autonomous space vehicle capable of orbital flight, re-entry and landing demonstration. Starting from high level requirements, the aeroshape class was identified and developed mainly looking at landing performances and mass reduction. Preliminary aerodatabases and re-entry trajectories were developed to assess also mission capability. Once the aeroshape and the mission scenario were identified system and subsystem analysis were performed to close the system loop. Main results of the system development are described.

The SPICE Door Mechanism (SDM) is foreseen to be flown on Solar Orbiter, to close the SPICE instrument aperture and shield it from the solar flux and from contamination. The environment it is exposed to is particularly extreme, as the Solar Orbiter mission will reach a distance of 0.28 AU (41’887’403.8 km) to the Sun, and the SPICE instrument will be looking directly at it. Because of its position at the far end of a cantilevered structure, the SDM is also exposed to amplified launch loads and must remain very light and compact. The cleanliness constraints are also very tight, as the mechanism is positioned directly at the aperture of the SPICE spectrometer. To tackle these issues, two novelties were introduced on the SPICE Door Mechanism: A specifically engineered reflective coating to protect the Aluminium door from the heat generated by the solar flux The use of miniature profile rail type linear bearings to support the door during launch and allow its motion during the mission T...

During the Validation Phase of the CIRA-PWT SCIROCCO Facility located at Capua (Italy), a test campaign has been carried out to verify the performances of the facility with the use of the two conical nozzle configurations "D" and "F" with exit diameters are, respectively of, 1150 and 1950 mm. For the first time the data results of the tests have been used to characterize the plasma flow in the test section of the facility. In particular, analytical relationships between the main thermo-fluid-dynamic parameters in the test section and the reservoir conditions of the facility have been found, and compared to the CFD prediction developed during the Design Phase of the facility. Very interesting has been the application of the boundary layer theory to calculate the displacement thickness at the nozzle exit section and the determination of the boundary layer thickness. Good agreement has been found between the boundary layer theory and the experimental results.

Recently developed OpenFOAM application hy2FOAM is employed to predict the aerodynamic heat transfer numerically and compared with the experimental data from the University of Illinois. Mach 7 nitrogen flow at 2.1 MJ/kg stagnation enthalpy, and Mach 7 nitrogen and air flows at 8 MJ/kg stagnation enthalpy over a double wedge geometry have been reproduced numerically assuming chemical and thermal non-equilibrium. Good agreement of mean heat transfer profiles has been observed, although none of the simulations achieved a steady-state. The reattachment heat transfer peak in the high enthalpy air case showed an improved agreement with the experimental data, which is due to the non-equilibrium in the flow field.

This paper presents the application of a Finite Volume Godunov-type implicit large eddy simulation method to study fuel injection into the combustion chamber of HyShot-II scramjet engine without combustion. Such a flow is generally termed as transverse jet injection into supersonic cross-flow. The HyShot-II experiment was successfully carried out at the UoQ, Australia. Subsequently, wind tunnel tests were carried out for the HyShot-II geometry for the conditions representing the Mach number of 7.4 at an altitude between 27 km and 35 km at the German Aerospace Centre (DLR). This study is carried out in two parts; part one presented full HyShot-II geometry in 2D in order to obtain the combustion chamber inlet conditions using the real gas effects, which are then utilised in part two where three-dimensional combustion chamber simulations are carried out using the inlet conditions obtained earlier along with hydrogen injection but without combustion. Supersonic turbulent boundary layer in the free-stream is an important aspect of such a flow which has been implemented using a digital filter based turbulent inflow data generator. The purpose of the study is to understand the flow physics and air & fuel mixing inside the HyShot-II scramjet geometry which is vital at the design stages. The work presented analyses the sonic circular hydrogen jet emerging into and mixing with a free-stream turbulent supersonic air flow. The flow physics is investigated for various flow features such as the Mach number, velocity, pressure distributions, counter rotating vortices, horseshoe vortices, jet penetration & mixing.

The paper investigates the influence of the thermochemical modeling on the flow-field properties for both compressing and expanding flows. For the nitrogen hypersonic flow over a cylinder a comparison between a model neglecting vibrational energy and two-temperature Park's nonequilibrium model has been performed in a wide variety of experimental and free flight conditions. It is shown that the differences are confined in a thin layer behind the bow shock while the overall flow properties are slightly affected. For the expanding air flows inside hypersonic facilities, besides the two models mentioned above, vibrational equilibrium and CVDV model have been compared. It was found that vibrational nonequilibrium can not be disregarded but no discernible differences have been observed between Park's and CVDV model results, unless the enthalpy is very large. Sommario. L'articolo analizza l'influenza della modellizzazione termochimica sul campo fluidodinamico nel caso di flussi ipersonici sia in compressione che in espansione. Per il flusso di azoto attorno ad un cilindroè stato effettuato un confronto fra un modello che trascura l'energia vibrazionale ed il modello di non-equilibrio a due temperature di Park. L'analisiè stata condotta per un ampio intervallo di variazione dei parametri caratteristici comprendente condizioni sia di volo che di prove in laboratorio. Il confronto ha mostrato che l'effetto del nonequilibrio vibrazionaleè sempre limitato ad una regione molto sottile dietro l'onda d'urto e che l'influenza sulle proprietà generali del flussoè in ogni caso modesta. Per il caso dei flussi in espansione in gallerie ipersoniche siè invece assunto come gas l'aria ed oltre ai due modelli già menzionati sono stati utilizzati anche il modello di equilibrio vibrazionale ed il modello CVDV. Siè osservato che per i flussi in espansione il non-equilibrio vibrazionale non può essere trascurato ma che comunque i modelli di Park e CVDV sono sostanzialmente equivalenti tranne nei casi di valori molto elevati dell'entalpia totale.

In this paper the ESA internal approach regarding the assessment of materials for inner solar system missions is presented. A main part of the work is devoted to the assessment of thermal control materials and space environmental testing at elevated temperature. As these materials are the most exposed it is important to understand how they will interact with the relevant space environment at elevated temperature. Driving parameters for materials degradation are discussed and ongoing testing efforts are described. An important input parameter for thermal models is the knowledge of the end of life values for the thermooptical properties as these determine the equilibrium temperatures. In certain cases end of life testing needs to be done when the uncertainty of extrapolation is too high.

The Integrated Thermal Response Modeling System consists of a twodimensional implicit thermal response and ablation program (TITAN), a commercialized finite-element thermal/mechanical analysis code (MARC), a high fidelity Navier-Stokes equation solver (GIANTS), and a boundary layer engineering correlation program (MEIT). This system is developed for fully coupled then-hal response analysis of

Numerical simulations of an arc heated flow inside NASA's 20 [MW] Aerodynamics heating facility (AHF) are performed in order to investigate the three-dimensional swirling flow and the current distribution inside the wind tunnel. The plasma is considered in Local Thermodynamics Equilibrium(LTE) and is composed of Air-Argon gas mixture. The governing equations are the Navier-Stokes equations that include source terms corresponding to Joule heating and radiative cooling. The former is obtained by solving an electric potential equation, while the latter is calculated using an innovative massively parallel ray-tracing algorithm. The fully coupled system is closed by the thermodynamics relations and transport properties which are obtained from Chapman-Enskog method. A novel strategy was developed in order to enable the flow solver and the radiation calculation to be preformed independently and simultaneously using a different number of processors. Drastic reduction in the computational cost was achieved using this strategy. Details on the numerical methods used for space discretization, time integration and ray-tracing algorithm will be presented. The effect of the radiative cooling on the dynamics of the flow will be investigated. The complete set of equations were implemented within the COOLFluiD Framework [1]. Fig. 1 shows the geometry of the Anode and part of the constrictor of the Aerodynamics heating facility (AHF) [2]. Fig. 2 shows the velocity field distribution along (x-y) plane and the streamline in (z-y) plane.

Effects of a jet emanating from the nose of a generic rocket in the opposite direction of the incoming freestream have been studied to determine the effects of the jet in reducing the drag and the heat loads on the rocket. The effects are comparatively evaluated for different jet exit Mach numbers from ideally expanded nozzles, designed using the method of characteristics, operating at a total temperature of 500 K and at total pressures with predetermined ratios of the freestream total pressure. Axisymmetric computations were conducted with the generic rocket flying at a Mach number of 6.0 and 40,000 ft altitude with zero-degree angle of attack. Results indicate that a jet generated by the Mach 1.5 nozzle, operating at a total pressure corresponding to 1/4th of the freestream total pressure, resulted in the best combined overall drag and temperature reduction. The area-averaged surface temperature and drag were reduced by 52%, and 22%, respectively, in comparison to the body without the flow control.

Este artigo busca demonstrar como argumentos centrais da obra de Maquiavel, muitos deles aprofundados por Hobbes e demais autores realistas, foram incorporados no início do século XX como base fundadora da disciplina de Relações Internacionais. Desde então, uma gama de autores contribuiu na elaboração do modelo teórico realista da Política Internacional. O realismo predominou nas discussões teóricas da disciplina durante décadas. Cumpriu a função essencial de institucionalizar as Relações Internacionais como campo de estudo independente nas Ciências Sociais. Entretanto, como efeito colateral, “encapsulou” lições clássicas de Maquiavel em arranjos analíticos reducionistas. Limitando assim, a fecundidade do pensamento maquiavélico à análise de agendas de pesquisa na área de Relações Internacionais. ABSTRACT This article searchs demonstrate how main arguments on Maquiavel´s work, many of them deepened by Hobbes and other realistics authors, were incoorporated on the begning of the XX c...

The objective of this work is to predict the optimal speed of an aerospace vehicle by aerothermochemical analysis of the hypersonic flow during atmospheric re-entry, out of equilibrium vibrational and chemical behind a detached strong shock. This study focuses on the influence of the ionization process that plays a significant role in the absorption of heat, because the characteristics of hypersonic flows are that molecules behind a strong shock wave become vibrationally excited, partially or completely dissociated and ionized depending on their bond energy, and the velocity of flow. On the other hand, we present the mathematical model that governs the flow of reactive gas mixture out of vibrational and chemical equilibrium that is composed of 79% nitrogen N2 and 21% oxygen O2. Conservation and relaxation equations (chemistry-vibration) are presented with particular importance to the expression of source terms. The numerical resolution method used is based on physical modeling, gove...

In this paper, we study the phenomena of thermo-chemical imbalance in a reactive monodimensional flow composed of a mixture of (79% nitrogen N2 and 21% oxygen O2). We are interested in modeling the physicochemical process that may be encountered in hypersonic flows, as vibrational excitation, dissociation and ionization, also the formation of chemical species to higher temperatures behind a detached strong shock. We put a special emphasis on vibrational relaxation model of CVD coupling. At these high temperatures, collisions electrons-atoms become very effective, taking in account the radiation that requires knowledge and modeling of all physicochemical processes (collisional and radiative). The mathematical model of flows at the atmospheric reentry is governed by Euler stationary equations coupled with the chemical kinetics and the radiative transfer equations. Our computational code is based on the finite differences method that used to discretize and resolve the obtained numerical model, where an appropriate mesh is selected in the relaxation zone in order to determine the flow parameters at each grid position

A new testbed for hypersonic flight research is proposed. Known as the Phoenix air-launched small missile (ALSM) flight testbed, it was conceived to help address the lack of quick-turnaround and cost-effective hypersonic flight research capabilities. The Phoenix ALSM testbed results from utilization of two unique and very capable flight assets: the United States Navy Phoenix AIM-54 long-range, guided air-to-air missile and the NASA Dryden F-15B testbed airplane. The U.S. Navy retirement of the Phoenix AIM-54 missiles from fleet operation has presented an excellent opportunity for converting this valuable flight asset into a new flight testbed. This cost-effective new platform will fill an existing gap in the test and evaluation of current and future hypersonic systems for flight Mach numbers ranging from 3 to 5. Preliminary studies indicate that the Phoenix missile is a highly capable platform. When launched from a high-performance airplane, the guided Phoenix missile can boost research payloads to low hypersonic Mach numbers, enabling flight research in the supersonic-to-hypersonic transitional flight envelope. Experience gained from developing and operating the Phoenix ALSM testbed will be valuable for the development and operation of future higher-performance ALSM flight testbeds as well as responsive microsatellite-small-payload air-launched space boosters.

Infrared thermography equipment is used to measure the temperature rise at a surface of a model simulating a deflected flap of a re-entry vehicle. The model is tested in the VKI-H3 hypersonic wind tunnel with a flow at Mach 6 at different Reynolds numbers and temperatures. Examining the rise of temperature on the interested surface, it is possible to visualize the flow topology on the surface and to infer the heat flux on the model. By heating artificially the model before the tests it is possible to evaluate the effects of the wall temperature on heat flux and flow topology.

Concepts for the operation of two fluid experiments in the mid-deck region of the STS were developed Based upon these concepts a preliminary design for each experiment is made. The two experiments are the Surface Tension Induced Convection experiment and the Free Surface Phenomena experiment. The mid-deck lockers of the STS are described and the requirements for operating an experiment in this region are described. For each locker the experiment design uses a two locker volume with an experiment unique structure as a housing. For the Surface Tension Induced Convection experiment a manual mode is developed. The fluid is maintained in an accumulator pre-flight. To begin the experiment a pressurized gas drives the fluid 'i nto the experiment conta i ner. The fluid is an inert silicone oil and the container material is selected to be compatable. A wound wire heater is located axisymmetrically above the fluid. The heater is designed to deliver three wattages to a spot on tne fluid surface. These wattages vary from 1-15 watts. The fluid flow is observed through the motion of particles in the fluid. The experiment container is illuminated by a 5 mw HeiNe laser. Scattered light is recorded on the film plane of a 35mm camera. The free surface phenomena experiment consists of a trapezoidal cell which is filled from the bottom The fluid is photographed at high speed using a 35mm camera which incorporated the entire cell 'Iength in the field of view. The assembly can incorporate four cells in one flight. For each experiment an electronics block diagram is provided. A control panel concept is given also for the surface tension induced convection. Both experiments are within the mid-deck locker weight and c-g 1 imits. 17. Key Words (Suggested by Author(s', 18. Distribution St.tamant mid-deck experiments Unclassified-Unlimited 'Iow gravity fluid behavior surface tension induced convection free surface phenomena low gravity research 19. Security Clallif. (olthitreport, 120. Security elllsif.

Concepts for the operation of two fluid experiments in the mid-deck region of the STS were developed Based upon these concepts a preliminary design for each experiment is made. The two experiments are the Surface Tension Induced Convection experiment and the Free Surface Phenomena experiment. The mid-deck lockers of the STS are described and the requirements for operating an experiment in this region are described. For each locker the experiment design uses a two locker volume with an experiment unique structure as a housing. For the Surface Tension Induced Convection experiment a manual mode is developed. The fluid is maintained in an accumulator pre-flight. To begin the experiment a pressurized gas drives the fluid 'i nto the experiment conta i ner. The fluid is an inert silicone oil and the container material is selected to be compatable. A wound wire heater is located axisymmetrically above the fluid. The heater is designed to deliver three wattages to a spot on tne fluid surface. These wattages vary from 1-15 watts. The fluid flow is observed through the motion of particles in the fluid. The experiment container is illuminated by a 5 mw HeiNe laser. Scattered light is recorded on the film plane of a 35mm camera. The free surface phenomena experiment consists of a trapezoidal cell which is filled from the bottom The fluid is photographed at high speed using a 35mm camera which incorporated the entire cell 'Iength in the field of view. The assembly can incorporate four cells in one flight. For each experiment an electronics block diagram is provided. A control panel concept is given also for the surface tension induced convection. Both experiments are within the mid-deck locker weight and c-g 1 imits. 17. Key Words (Suggested by Author(s', 18. Distribution St.tamant mid-deck experiments Unclassified-Unlimited 'Iow gravity fluid behavior surface tension induced convection free surface phenomena low gravity research 19. Security Clallif. (olthitreport, 120. Security elllsif.