Hypersonic Ramjets Research Articles

French-Russian Partnership on Hypersonic Wide-Range Ramjets

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. Copyright 1996 by AEROSPATIALE and Moscow Aviation Institute. Published by the American Institute of Aeronautics and Astronautics, Inc with permission. The use of kerosen and then hydrogen on the trajectory, the study of integration of detonation-based cycle to the Wide Range Ramjet, the solutions for the movable parts are particulary studied in this cooperation. The test methodology and in particular the scale effect between the full scale space launcher, a 30 meter medium vehicle and a small Flying Test Bed, are also under common study.

Effects of thermal compression on the performance estimates of hypersonic ramjets.

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Turbulent transport coefficients in supersonic flow

Hypersonic ramjets employing supersonic combustion of hydrogen fuel have attractive potentialities for future aircraft or launching systems. The object of the present work §§This work was sponsored by the Office of Aeronautical Research, Office of Advanced Research and Technology, National Aeronautics and Space Administration, Washington, D.C. The Applied Physics Laboratory operates under Contract NOw 62-064c with the Bureau of Naval Weapons, Department of the Navy. was to study quantitatively the effects of fuel injection parameters on the mixing of gaseous hydrogen fuel with a supersonic air stream confined within a cylindrical duct, to provide some of the fundamental background needed for the design of supersonic combustors for high-performance engines. Hydrogen was injected at sonic velocities into Mach 2 and Mach 3 air streams, at overall equivalence ratios of 0.17 to 0.50, in both radial and axial (downstream) directions from circumferential wall slots. Results showed that considerably better mixing occurred in the case of radial injection, although the decrease in stagnation pressure also was greater for this case.The eddy diffusivity of mass, Ed (turbulent diffusion coefficient) and radial velocity, Vr, were determined by differentiating experimental concentration, velocity and density profiles, obtained at various axial distances from the injection station. For the radial injection case, with a 1-in i.d. test section, a simple model in which Ed varied only in the radial direction and Vr varied only in the axial direction, allowed reasonable correlation of the experimental results. The validity of the trends obtained in Ed and Vr were checked by numerical integration of the diffusion equation, and simultaneous solution of the diffusion and momentum equations; computed profiles agreed reasonably well with downstream experimental concentration and velocity profiles. A method for solving turbulent mixing problems by simultaneous solution of the diffusion, momentum and energy equations is presented.

Chemical and nozzle flow losses in hypersonic ramjets

Chemical and nozzle flow losses in hypersonic ramjets

Ear‐to‐ground

RAMJET RAMIFICATIONS. ‘Hands across the sea’ was the order of the day for Bristol Siddeley Engines Ltd. when they announced recently that they had signed a format agreement for the exchange of information relating to advanced propulsion systems with the Marquardt Corporation of America. The agreement has the blessings of the governments of both the United States and the United Kingdom. Initially, at least, collaboration will be limited to an exchange of technical knowledge concerning supersonic and hypersonic ramjets, and their subsystems and components. Bristol Siddeley are currently producing the ThorBT.1 ramjet—incidentally the first ramjet power unit to go into production in Europe—for the Bloodhound surface‐to‐air guided missile, as welt as carrying out work on a number of other projects including the BSRJ‐824 ramjet for long‐range operations at high altitudes.

Kinetics in hydrogen-air flow systems. I. Calculation of ignition delays for hypersonic ramjets

An analytical method of estimating auto-ignition delay time based on dissociation and recombination rates of gases has been developed. In this analytical method, the one-dimensional gas-dynamics equations are combined with reaction-kinetics equations to formulate a, set of ( n +5) simultaneous, nonlinear-first-order differential equations, where n is the number of species considered. These equations describe the behavior of a mixture of reacting gases flowing supersonically down a duct. A computer program has been evolved and used to solve these equations for the particular case of hydrogen-air mixtures. The ignition delay periods obtained through this program are in good agreement with the limited amount of experimental data available for hydrogen and air.

Recombination and Condensation Processes in High Area Ratio Nozzles

D or evaporated species that do not recombine or condense to equilibrium values during expansion in the nozzle of a rocket or air breathing engine may represent a large thrust loss. Data and understanding on recombination and condensation rates are needed for predicting engine performances such as hypersonic ramjets, chemical rockets, and nuclear rockets. Trends to higher operating temperatures, expansion to lower pressures, and use of metals or their compounds in fuel lead to the increasing importance of the chemical and physical processes in nozzles. This paper summarizes information on nozzle processes for certain systems of current interest; essentially it brings Ref. 1 up to date. In particular, the effect of recombination on performance, some implications to design, and data and analyses are presented for hydrocarbon-air, hydrogen-air, hydrogenfluorine, hydrogen-oxygen, jet fuel-oxygen, metallized propellant, and heated hydrogen systems. Not all available information in the field is treated, but the grosser aspects of the problem are highlighted. The systems discussed are examples of the three types of study that can be considered for evaluating nozzle performance. First, applying rate data to evaluate nozzle performance can be accomplished by solving a set of equations relating the flow, thermodynamics, and kinetics of the system. One difficulty in this rigorous approach is the mathematical complexity of including a number of processes. For example, assume that the hydrogen-air system requires consideration of four elementary reactions and seven species as follows:

Relative Thermodynamic Efficiency of Supersonic Combustion and Subsonic Combustion Hypersonic Ramjets

Relative Thermodynamic Efficiency of Supersonic Combustion and Subsonic Combustion Hypersonic Ramjets