Marc Bouchez

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 laboratorys 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.

Advanced Composite Materials for Current and Future Propulsion and Industrial Applications

Various technology programmes in Europe are concerned with preparing for future propulsion technologies to reduce the costs and increase the life time of components for liquid rocket engine components. One of the key roles to fulfil the future requirements and for realizing reusable and robust engine components is the use of modern and innovative materials. One of the key technologies which concern various engine manufacturers worldwide is the development of fibrereinforced ceramics – CMCs (Ceramic Matrix Composites). The advantages for the developers are obvious – the low specific weight, the high specific strength over a large temperature range, and their good damage tolerance compared to monolithic ceramics make this material class extremely interesting as a construction material. Different kind of composite materials are available and produced by EADS ST, the standard material SICARBON® (C/SiC made by Liquid Polymer Infiltration) and the new developed and qualified composite materials SICTEX® (C/SiC made by Liquid Silicon Infiltration) and CARBOTEX® (C/C made by Rapid Chemical Vapour Infiltration). The composites are based on textile techniques like weaving, braiding, stiching and sewing to produce multiaxial preforms, the SICTEX® material is densificated by the cost effective Liquid Silicon Infiltration (LSI). Over the past years, EADS Space Transportation (formerly DASA) has, together with various partners, worked intensively on developing components for airbreathing and liquid rocket engines. Since this, various prototype developments and hot firing-tests with nozzle extensions for upper and core stage engines and combustion chambers of satellite engines were conducted. MBDA France and EADS-ST have been working on the development of fuel-cooled composite structures like combustion chambers and nozzle extensions for future propulsion applications.

Hydrocarbon fueled airbreathing propulsion for high speed missiles

Sustained airbreathing hypersonic flight shows potential operational advantages for military applications. In particular future missiles or drones will give crucial benefit if they fly at hypersonic speeds in the atmosphere. High speed ramjets (scramjet and dual mode ramjet) are well-known as key-technology for these future systems. Military applications are typically associated with liquid hydrocarbons, generally with a maximum Mach number about 8 and non reusability. Advanced studies of such missiles have been performed at AEROSPATIALEMissiles. Reusability could be specified for recognition missiles or high speed aircraft. The main purposes of the presented advanced studies of high speed missiles are to head-line the potential interest of hypersonic speeds in comparison to the present near-term missiles and to address the pinch points in order to lead the technological studies. Hydrocarbon scramjet studies have been supported by internal funding since 1985. Integration of airbreathing propulsion to high speed missiles deals in particular with forebody characterization, air intake design and several trade-offs such as the relative length between the air intake, the combustor and the nozzle. High speed combustion of kerosene in an actual scramjet is one of the topics to be addressed. This work deals with analytical design, experimental studies and CFD computation (two-phase flow full NavierStokes). The thermo-structural point of view has to be taken into account in the preliminary design of hydrocarbon fueled scramjets. Advanced materials, use of endothermal fuels and other new concepts could solve a lot of problems but with a need of technological risk reduction and with a system complexity more difficult to be successfully managed on the whole mission. Preliminary studies of hydrocarbon cooled structures have then been conducted. Hydrocarbon-fueled scramjet combustors have been studied at AEROSPATIALEMissiles using analytical codes and CFD analysis. Two phase flow Navier-stokes computations of kerosene-fueled scramjet combustor have been performed. First tests of kerosene fueled scramjet have been conducted by AEROSPATIALE Bourges. Copyright

Experimental Investigation of Cooling Techniques and Materials for Highspeed Flight Propulsion Systems

The multidisciplinary design process of future supersonic and hypersonic flight vehicles implies the development of propulsion systems using sophisticated cooling techniques in combination with advanced materials. Within the framework of the European research project ‘Aerodynamic and Thermal Load Interactions with Lightweight Advanced Materials for High Speed Flight’, in short ATLLAS, different cooling techniques using both metallic and ceramic materials for propulsion systems are under investigation. The hot fire experiments deal with the application of film and transpiration cooling in operating conditions beyond the scope of conventional aeroengines. Different newly developed ceramic materials are studied with respect to their applicability in oxidizer rich as well as fuel rich combustion atmospheres and operating conditions typical for the high-pressure turbojet and ram-based lower pressure engines. The information gained in the different test programs is fed back to the project partners engaged in the development of design and simulation tools and used as an input for the MDO design process of the overall propulsion system.

Semi-empirical and CFD analysis of actively cooled dual-mode ramjets : 2006 status

Dual-mode ramjets could thrust future hypersonic vehicles such as Reusable Space Launchers, and in particular SSTO. If the propulsive performance have to be computed, optimised and if possible demonstrated, a major challenge is the capacity to build such an engine, and to estimate its robustness and its weight. System studies, technologies demonstration and computational techniques have been under concern at MBDA France from conventional ramjets to hypersonic engines. Aerodynamical, chemical, mechanical and thermal investigations of composite and metallic structures have been carried out, using both analytical tools and 3-D numerical simulations.

Multi-Level Coupled Simulations of Cooled Structures in the ATLLAS European Programme

The objective of the 3 years ATLLAS program is to identify and assess lightweight advanced materials which can withstand ultra high temperatures and heat uxes enabling high-speed ight above Mach 3. Indeed, classical materials used for airframes and propulsion units are not longer feasible at these high speeds and need to be replaced by hightemperature, lightweight materials, with active cooling of some parts. Three main issues are considered within the project. First, the overall design for highspeed transports is revisited with Mach 3 and Mach 6 cruising options, taking into account sonic boom reduction. Second, materials and cooling techniques and their interaction with the aero-thermal loads is addressed for both the airframe and propulsion components. Finally, since particular aero-thermal-material interaction strongly in uences the aerothermal loadings, conjugate heat transfer, transpiration cooling and compressible transition phenomena are investigated and modeled. The present paper gives the status of this part of the ATLLAS work, dealing with numerical toolbox enhancement.

SFGP 2007 - Pyrolysis of Supercritical Endothermic Fuel: Evaluation for Active Cooling Instrumentation

Hypersonic flight is expected to be achieved in the coming years by use of Supersonic Combustion RAMJET (SCRAMJET). One of the main issues is the thermal management of the overall vehicle and more specifically the cooling of the engine. In order to simulate the behaviour of an actively cooled SCRAMJET by use of supercritical endothermic fuel, a one-dimensional transient numerical model has been developed with heat and mass transfer, fluid mechanics and detailed pyrolysis chemistry. A dedicated experimental test bench is now available since 2006 at the LEES laboratory of Bourges to study supercritical fuel pyrolysis under steady-state and transient conditions. It aims to provide understanding of coupled phenomena, validation data for the numerical code and evaluation of onboard and real-time measurement methods for industrial use. A brief overview of the numerical code and a presentation of the experimental bench are proposed in this paper. Experimental results are discussed and a comparison is provided between numerical and experimental data. Discrepancies are shown to be lower than a few percent in terms of molar chemical compositions. This is due to uncertainties on experimental temperature measurement and to 2-D effects, which are not taken into account by the modelling. The numerical code appears to be of great importance in accessing unmeasured data and providing new understanding of coupled phenomena. Experimental and numerical tools are proved to be efficient to test future measurement methods under extreme conditions, especially at supercritical states.

Characterization of supercritical reactive flow for hypersonic real-time application

In the framework of the hypersonic propulsion, with cooled engine by endothermic hydrocarbon fuel, it is necessary to provide adapted measurement methods for the cooling regulation as for the control of the engine thrust. The sensors should be robust because of the extreme in-flight conditions, of vehicle acceleration and vibration, of the fluid temperature (1500 K) and pressure (3.5 MPa) and of the multi-component supercritical mixture. Their response time should be lower than one second. Therefore, a large range of real time and on line measurement methods has been tested and some of these methods among the most promising are presented in this paper. The aim is not to necessarily develop a new technology but to evaluate the feasibility and the adaptability of existing ones for our purpose, even if those are not especially dedicated for it. Numerical evaluation is firstly conducted then some of the techniques are experimentally tested. Two of them, the sonic throat and the Fourier Transform Infra Red spectroscopy (FTIR), appear to be particularly promising and allow uncertainties of few percents. The first one allows evaluating the mass flow rate of a supercritical reactive mixture. The second one characterizes the chemical composition before injection in the combustion chamber, for mole fraction greater than 5 %. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc.

Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management

The last years saw a renewal of interest for hypersonic research in general and regenerative cooling specifically, with a large increase of the number of dedicated facilities and technical studies. In order to quantify the heat transfer in the cooled structures and the composition of the cracked fuel entering the combustor, an accurate model of the thermal decomposition of the fuel is required. This model should be able to predict the fuel chemical composition and physical properties for a broad range of pressures, temperatures and cooling geometries. For this purpose, an experimental and modeling study of the thermal decomposition of generic molecules (long-chain or polycyclic alkanes) that could be good surrogates of real fuels, has been started at the DCPR laboratory located in Nancy (France). This successful effort leads to several versions of a complete kinetic model. These models do not assume any effect from the material that constitutes the cooling channel. A specific experimental study was performed with two different types of steel (regular: E37, stainless: 316L). Some results are given in the present paper.

Numerical and experimental validation of transient modelling for Scramjet active cooling with supercritical endothermic fuel

One of the main issues of hypersonic flight is the thermal management of the overall vehicle and more specifically the cooling of the engine. In order to simulate the behaviour of a complete actively cooled scramjet, a one-dimensional transient numerical model has been developed with heat and mass transfer in a cooling channel for supercritical fuel under pyrolysis. This model is called RESPIRE (French acronym for Scramjet Cooling with Endothermic Fuel., Transient Reactor Programming). A supplementary step by step validation of the model, based on 2-D numerical data from CFD-ACE, is presented in this paper. On stationary cases, fluid temperature profiles are in good agreement and values are comprised between those of centre fluid and those of near-wall fluid. Effects of one-dimensional semi-empirical correlations are shown and the boundary layer impact at the channel entrance is of great importance on wall temperatures. Heat fluxes conservation is verified and hydraulic behaviour too. On transient cases, temperature and velocity evolutions are well followed. Values after the change in mass flow rate are exactly those of stationary test case. RESPIRE is quantitatively validated under stationary and transient conditions and can be used to compare with experimental data. Qualitatively good agreement is found with experimental results on a chemical aspect.