Francois Falempin

R&T Effort on Pulsed and Continuous Detonation Wave Engines

Due to its thermodynamic cycle, the pulsed detonation engine (PDE) has theoretically a higher performance than classical iso-pressure combustion propulsion concepts. Nevertheless, PDE design must avoid this advantage being not fully compensated by the difficulties encountered for practical use of the PDE concept or by the complex technology, which could be needed to implement it in an operational flying system, particularly due to severe generated vibration environment. The Continuous Detonation Wave Engine (CDWE) can also be considered to reduce the environmental conditions generated by PDE while reducing the importance of initiation issue and simplifying some integration aspects. Specific experimental program has been performed by MBDA and Lavrentiev Institute to understand unsteady, three dimensional flow behind the detonation wave and to address some key points for the feasibility of an operational rotating wave engine for space launcher. On the basis of these results, a preliminary design of an operational engine has been performed by taking into account all engine/airframe integration issues in order to optimize the ben efit of detonation wave engine. Beyond these first steps, MBDA designed a large scale ground demonstrator allowing to address all issues for a continuous detonation rocket engine using LH2/LOx mixture. As a first step toward the development of this large scale engine, a small scale demo is to be tested in Fall 2009.

French Flight Testing Program LEA Status in 2009

French R&T effort for hypersonic airbreathing propulsion is focusing on needed technologies for the propulsion system and acquisition of aero-propulsive balance prediction capability. A large part of technology development effort can be led on ground and is currently dedicated to combustion chamber to ensure its performance and thermomechanical strength. On the contrary, it is mandatory to flight demonstrate capability to predict the aero-propulsive balance. In that view, MBDA and ONERA are leading the flight testing LEA program. Started in January 2003, the program will end in 2015 after 4 autonomous flight tests of an experimental vehicle in Mach number range 4 to 8. Guidelines for LEA vehicle and its propulsion system design have been validated in 2006 by a Preliminary Design Review. The running Phase 2 aims at getting a detailed design while validating the aero-propulsive configuration by a first free jet test series to be performed early in 2011. It led to a Critical Design Review performed in June/July 2009.

Pulsed and Rotating Detonation Propulsion Systems : First Step Toward Operational Engines

Due to its thermodynamic cycle, a detonation wave engine has theoretically a higher performance than an other classical propulsion concept using the combustion process. Nevertheless, it still has to be proved that this advantage is not compensated by the difficulties which could be encountered to practically define a real engine and to implement it in an operational flying system. For space launcher, the application of detonation wave propulsion to the liquid rocket engine could strongly increase the specific impulse and improve the feasibility of a full rocket SSTO. But, obtaining this result probably needs to radically change the concept of the vehicle in order to take all the advantage of the detonation wave process but also to limit the technology needs and to mitigate the dry mass increase, due to the generated environmental conditions. For military application, and for Europe, it seems that the application to an aircraft can not be considered in the near or middle term future. On the contrary, the airbreathing detonation wave engine could be very attractive for low cost missiles and UAV. Indeed, for these applications, a detonation wave engine with simplified technology could provide an economic alternative to the turbo-engine, particularly in the field of very small caliber turbo-engine. If PDE seems promising in air- breathing mode, for rocket engine the use of rotating detonation wave (CDWRE) can also be considered to reduce the environmental conditions generated by PDE while reducing the importance of initiation issue and simplifying some integration aspects. Such a concept has been studied since a long time, particularly at Lavrentiev Laboratory in Novosibirsk. As it was done for PDE, specific experimental program is being performed by MBDA and Lavrentiev Institute to assess some key points for the feasibility of an operational rotating wave engine for space launcher : detonation of two-phase mixture, limitation of injection pressure, feasibility of thrust vectoring… and the main results of this experimental program will be summarized in the paper. On the basis of these results, a preliminary design of an operational engine is under progress taking into account all engine/airframe integration issues in order to optimize the benefit of detonation wave engine. The main options of this design will be presented and discussed in the paper before a global performance evaluation.

A Contribution to the Development of Actual Continuous Detonation Wave Engine

During past years, MBDA performed some theoretical and experimental works, mainly in cooperation with LCD laboratory at ENSMA Poitiers, on Pulsed Detonation Engine (PDE). These studies aimed at obtaining a preliminary demonstration of the feasibility of the PDE in both rocket and airbreathing modes and at verifying the interest of such a PDE for operational application : rocket and airbreathing mode experimental evaluation, effect of filling coefficient, effect of a nozzle, thermal, mechanical, acoustic and vibrations environment generated, evaluation of different fuels, performance code development. Due to its thermodynamic cycle, the pulsed detonation engine (PDE) has theoretically a higher performance than an other classical propulsion concept using the combustion process (+ 20 to 25% in term of thermal efficiency). Nevertheless, it is necessary to verify that this advantage is not fully compensated by the difficulties, which could be encountered for practical use of the PDE concept or by the complex technology, which could be needed to implement it in an operational flying system. Moreover, a PDE a priori generates a severe vibration environment, which can imply higher more severe requirement for all on-board vehicle equipments or subsystems. After some in house studies performed in national and international cooperation, MBDA is now focusing its efforts to the development of a demonstration engine led in cooperation with Singapourian DSO in order to really assess the feasibility and the interest of this propulsion concept.

LEA Flight Test Program - Status in 2004

During the 10 last years, a large Research and Technology effort has been led by MBDA and ONERA to develop knowledge on high-speed airbreathing propulsion and master associated technologies. Development of operational, civilian or military, application of the hypersonic airbreathing propulsion depends of two key points : development of needed technologies for the fuel-cooled structure of the propulsion system, capability to predict with a reasonnable accuracy and to optimise the aeropropulsive balance (or generalized thrust-minus-drag balance). The most part of the technology development effort can be led with available ground test facilities and classical numerical simulation (thermics, mechanics

Recent experimental results obtained on Continuous Detonation Wave Engine

Due to its thermodynamic cycle, the Continuous Detonation Wave Engine has theoretically a higher performance than classical iso-pressure combustion propulsion concepts. CDWE can also be considered to reduce the environmental conditions generated by other detonation engines such as PDE while reducing the importance of initiation issue and simplifying some integration aspects. After performing some specific experimental and numerical programs at LIH, MBDA designed a preliminary demonstrator of CDWE with the support of the EADS Nursery. A first assessment of the tests in progress is presented in the following article.

Flow Control in Model Supersonic Inlet by Electrical Discharge

The paper is aimed to present the results of experimental and computational research in a field of supersonic Flow Control by means of near-surface electrical discharge generation. The specific task of this activity is to demons trate the steering effect of low-temperature nonequilibrium plasma on supersonic flow structure in a compression ramp. The experiments were arranged in connected pipe configuration (lab-scale) at M=2-2.5. CFD efforts in 3D NS approach clarify extra features of plasma-flow-surface interaction.

Design of a Continuous Detonation Wave Engine for Space Application

*† ‡ § ** The last years showed a renewed interest in space exploration with the announcement of new and ambitious space programs. The prospect of the near term return of manned missions to the moon or the development of clusters of small-size satellites imply that we need simple and affordable access to space. Detonation wave engines, thanks to their more efficient thermodynamic properties, are expected to exhibit a higher level of performance than more conventional propulsion system that rely on constant-pressure combustion processes. Nevertheless, it still has to be proved that this advantage is not superseded by the difficulties which could be encountered to practically define a real engine and to implement it in an operational flying system. Application of detonation wave propulsion to the liquid rocket engine could increase the specific impulse and improve the feasibility of a full rocket SSTO, but obtaining this result probably needs to radically change the concept of the vehicle in order to take all the advantage of the detonation wave process. During past years, MBDA performed some theoretical and experimental works, mainly in cooperation with the Lavrentyev Institute of Hydrodynamics in Novosibirsk. These studies aimed at obtaining a preliminary demonstration of the feasibility of a Continuous Detonation Wave Engine (CDWE) for air-breathing and rocket application. Compared to a Pulsed Detonation Engine, this design allows an easier operation in reducedpressure environment and an increase in engine mass flow rate and thrust-toweight ratio. Those studies were focused on global performance and understanding of the unsteady, three dimensional flow behind the detonation wave. Investigations were conducted to gain knowledge of the noise generated by a CDWE operating at several kiloHertz, heat fluxes (intensity, areas) and cooling strategies, composite materials (Carbon / Silicon Carbide) compatibility, engine thrust vectoring capability and pollution (for air-breathing application). Those results were used to validate 1-D and 2-D unsteady computations. Discrepancies between numerical results and analytical flow-solutions were found that highlight the difficulties of detonation waves simulations. On the basis of these results, a preliminary design of an operational engine is under progress taking into account all engine/airframe integration issues in order to optimize the benefit of detonation wave engine. The main options of this design will be presented and discussed in the paper before a global performance evaluation

LAPCAT 2 - Axisymmetric Concept for a Mach 8 Cruiser Preliminary Design and Performance Assessment

1 Head of Future Powered Airframe, MBDA France, francois.falempin@mbda-systems.com 2 R&D engineer, hypersonic propulsion, MBDA France, marc.bouchez@mbda-systems.com 3 R&D engineer, hypersonic propulsion, MBDA France, vincent.perrillat@mbda-systems.com The LAPCAT 2 program, led under ESA/ESTEC technical coordination in the European Union Framework Program FP7, aims at preliminary designing a high-speed civilian transport airplane able to perform very long range and at acquiring some associated necessary knowledge. Two options are considered : one airplane cruising at Mach 5 and another cruising at Mach 8.

First steps for the development and testing of a Pulse Detonation Engine for UAV application

Due to its thermodynamic cycle, the pulsed detonation engine (PDE) has theoretically a higher performance than an other classical propulsion concept using the combustion process (+ 20 to 25% in term of thermal efficiency). Nevertheless, it is necessary to verify that this advantage is not fully compensated by the difficulties, which could be encountered for practical use of the PDE concept or by the complex technology, which could be needed to implement it in an operational flying system. Moreover, a PDE a priori generates a severe vibration environment, which can imply higher more severe requirement for all on-board vehicle equipments or subsystems. On the basis of knowledge acquired during the last ten years, MBDA and DSO started a collaboration devoted to the pre-development of a small-scale PDE demonstrator that could be flight tested within the next years. This demonstrator should use storable fuel, be throttle-able, provides a good specific impulse in a small-size engine with a good thrust-to-weight ratio and minimum maintenance cost. This demonstrator should also be able to operate in a complete airbreathing mode, without onboard oxidizer, so the design of the ignition device is one of the key points of this engine, the other being the inlet integration and the capability to provide continuous inlet flow even with a pulsed combustion chamber operation. Since the repetitive and direct initiation of a detonation inside a PDE requires large amount of energy and hence high power consumption, two other low-energy mechanisms are generally used, they are deflagration-to-detonation transition (DDT) and Shock-to-detonation transition (SDT). Pre-detonation tubes with Shchelkin spirals are commonly found on most PDE concept. The mechanism involved is both DDT and SDT. Inside the pre-detonation tube, the flame accelerates from low-velocity laminar (or turbulent in some cases) to medium velocity turbulent regime, up to the thermal blockage velocity, and ultimately up to real CJ detonation velocity. For fuel – air mixture, the pre-detonation tube diameter is generally marginally larger than one detonation cellsize, so when the detonation diffracts into the main chamber, the sudden expansion from confinement results in decay of the reaction zone and decoupling from the shock wave in the subcritical regime (complete propagation failure as shock decouples from the reaction zone). In this case, re-ignition of the detonation could only be achieved by shock – shock interactions (main shock and reflected shock waves from the walls), so after the DDT inside the pre-detonation tube we could observe a SDT inside the main chamber. During the detonation phase, the pressure inside the chamber is higher than the total inlet pressure so without careful design some parts of the hot gases could be exhausted thru the inlet, decreasing both impulse from the detonation and engine operating frequency. The paper describes the numerical and experimental investigations on shock waves generated by fast flames as well as some work related to engine integration, performed by DSO and MBDA, in order to develop a first version of an operational ignition device for the envisioned PDE.