Intermediate eXperimental Vehicle Research Articles

Plasma Effect on Radiofrequency Communications for Lifting Reentry Vehicles

The present work investigates plasma effects around two lifting hypersonic vehicles and their implications on the radiofrequency communication blackout performances during the Earth atmospheric reentry phase. In particular, the Intermediate Experimental Vehicle developed by the European Space Agency and a slender, high lift-over-drag space plane, investigated during previous studies, have been taken into account. Chemical nonequilibrium analyses have been carried out by means of a numerical code, updated with a customized chemical model comprised of several reacting species and different reaction mechanisms. Different flight conditions, including the most critical for communications, have been considered for both vehicles. The main outcomes of the study show that, for very similar freestream conditions, the slender space plane exhibits better communication capabilities when compared with the Intermediate Experimental Vehicle. Particularly, the results suggest that the Intermediate Experimental Vehicle would be able to communicate from the lee side for a limited range of the angle of sight, while no communications from the wind side would be possible. On the other hand, for the slender space plane, flying at relatively low angles of attack, communications are possible either from the lee side or the wind side with very wide angles of sight.

Modeling of reentry space vehicle aerodynamics with control thruster plume — free-stream interaction

Changes in aerodynamic characteristics of a space vehicle model due to interaction of the control thruster plume with the incoming flow are numerically studied. Parameters of the plume escaping from the thruster nozzle and flight data (velocity and altitude) are taken to be the parameters of the Intermediate eXperimental Vehicle. Simulations are performed by the Direct Simulation Monte Carlo Method. A multizone approach is used for combined modeling of the dense plume and the rarefied incoming flow. If the control thruster plume is fairly close to the space vehicle surface, flow interference is possible, which may alter the force and moment characteristics. In the problem considered in this paper, the pitching moment changes approximately by 10 % at altitudes below 120 km due to this interference.

Passive/active oxidation transition for CMC structural materials designed for the IXV vehicle re-entry phase

This paper reports the experimental results of oxidation studies for the determination of the transition between passive and active oxidation of two silicon carbide-based materials produced by Herakles-Safran (France) and MT Aerospace (Germany) with also the study of the oxidation kinetics in the active zone for the highest heating conditions of the Intermediate eXperimental Vehicle (IXV) re-entry trajectory. The transition between active and passive oxidation is determined for both materials using two different plasma facilities – a low enthalpy one using the MESOX at PROMES-CNRS (Font-Romeu Odeillo, France) and a high enthalpy one using the Plasmatron at VKI (Rhode St Genèse, Belgium) – and the experimental results lead to the same transition law. Characterization by SEM of the oxidized samples (surface and cross-section) is shown. Mass loss rates in active oxidation conditions are reported for both Herakles and MTA materials.

Aerodynamic database development of the ESA intermediate experimental vehicle

This work deals with the aerodynamic database development of the Intermediate Experiment Vehicle.The aerodynamic analysis, carried out for the whole flight scenario, relies on computational fluid dynamics, wind tunnel test, and engineering-based design data generated during the project phases, from rarefied flow conditions, to hypersonic continuum flow up to reach subsonic speeds regime. Therefore, the vehicle aerodynamic database covers the range of Mach number, angle of attack, sideslip and control surface deflections foreseen for the vehicle nominal re-entry. In particular, the databasing activities are developed in the light of build-up approach. This means that all aerodynamic force and moment coefficients are provided by means of a linear summation over certain number of incremental contributions such as, for example, effect of sideslip angle, aerodynamic control surface effectiveness, etc.Each force and moment coefficient is treated separately and appropriate equation is provided, in which all the pertinent contributions for obtaining the total coefficient for any selected flight conditions appear.To this aim, all the available numerical and experimental aerodynamic data are gathered in order to explicit the functional dependencies from each aerodynamic model addend through polynomial expressions obtained with the least squares method. These polynomials are function of the primary variable that drives the phenomenon whereas secondary dependencies are introduced directly into its unknown coefficients which are determined by means of best-fitting algorithms.

European Space Agency intermediate experimental vehicle: Development of an independent aerothermodynamic database tool

In the frame of the European Space Agency (ESA) Intermediate eXperimental Vehicle (IXV) project, ESA is coordinating a series of technical assistance activities aimed at verifying and supporting the IXV industrial design and development process. The technical assistance is operated by the Italian Space Agency, by means of the technical support of the Italian Aerospace Research Centre. One of the purposes of the activity is to develop an independent capability for the assessment and verification of the industrial results with respect to the aerothermodynamic characterization of the IXV vehicle. To this aim, CIRA have developed an independent aerothermodynamic database, intended as a tool generating in output the time histories of local quantities for each point of the IXV vehicle surface and for each trajectory, together with an uncertainties model. The whole procedure followed for the definition of the numerical tool and the main results achieved will be presented in this article.

Effect of steps and gaps on aerothermodynamics for the IXV hypersonic vehicle

The general aerothermodynamics environment of hypersonic vehicles is usually performed considering a smooth simplified geometry. However, in the case of the intermediate experimental vehicle (IXV), the thermal protection system includes a mono-block ceramic matrix composite nose and an assembly of shingles between which steps and gaps are generated. From an aerothermodynamic point of view, such a distributed roughness layout cannot be ignored in terms of modification of the interaction between the flow and the body and possible induced transition along the windward side. To assess these effects, dedicated wind tunnel tests and numerical simulations have been performed. This paper presents the general logic of the work, with emphasis on the wind tunnel model design, tests involving infrared thermal measurements as well as the computational fluid dynamics (CFD) rebuilding of the flow in the wind tunnel and the extrapolation from ground to flight.

Development of thermal protective seal for hot structure control surface actuator rod

For the Intermediate eXperimental Vehicle (IXV) the deflection of the highly loaded body flap is performed by an actuator system which is connected to the body flap by a rod. Besides the thermal and mechanical loads the sealing of the inner vehicle against the possible leaking hot plasma is an important issue whereby the special challenge for the design results from the spatial movement of the rod. This requires a design consisting of different parts and various materials in order to satisfy the mechanical flexibility and the resistance to the thermal and mechanical loads under the aspect of reusability. This paper describes the MT Aerospace approach for the thermal protection system for the actuator as presented for the critical design review of IXV. The design is presented and described including all necessary performed analysis steps toward such a design.

Experimental investigation of the influence of the flow structure on the aerodynamic coefficients of the IXV vehicle

In the framework of the ESA Future Launchers Preparatory Program (FLPP) an experimental study on the aerodynamic behavior during the re-entry phase of the Intermediate eXperimental Vehicle (IXV) configuration was conducted in the DLR hypersonic wind tunnel H2K in Cologne. Tests were carried out at Mach 6.0 and 8.7 with different flap deflection angles and the angle of attack varied continuously between 20° and 55° to investigate the flow topology as well as the aerodynamic forces and moments and the surface pressure distribution. The experimental data show that depending on the combination of the flap deflection angle (δL/R) and angle of attack (α) the complex flow structure in the vicinity of the flaps significantly influences the vehicle’s aerodynamic coefficients. An analysis of this shock/shock and shock/boundary layer interaction causing flow separation with reattachment is performed.

Experimental and Numerical Investigation of Aerothermal Characteristics of Hypersonic Intermediate Experimental Vehicle

Cp = pressure coefficient h = altitude, km k = transition tripping device height, mm L = vehicle length, m M = Mach number P = pressure, pa q = convective heat flux, kW=m Re = Reynolds number T = temperature, k X = distance along vehicle forebody running from nose, m Y = spanwise vehicle coordinate, m = angle of attack, deg = angle of side slip, deg = surface control deflection angle, deg = emissivity coefficient