Marco Di Clemente

Shock Wave Boundary Layer Interaction in EXPERT Flight Conditions and "Scirocco" PWT

One of the most challenging problems of modern aerospace engineering is the prediction of hypersonic flows, both for the complexity of the required physical modelling and for the impossibility to duplicate in wind tunnel the real flight conditions due to the high energy levels required. Experimental and numerical investigation techniques must be combined and mutually validated and improved. In the frame of the ESA-EXPERT programme, the main goal of Payload #07 is to design and execute a flight experiment on shock-wave boundarylayer interaction with flow reattachment on control surfaces in order to collect flight data to be used for a post-flight analysis and assessment of a methodology for the extrapolation-toflight of the interesting parameters of such flows. Another aspect of this payload concerns with the duplication of the conditions over the flap in a high enthalpy ground facility; to this aim, it is necessary to correlate the numerical and experimental plasma wind tunnel results with those predicted and, then, measured during the flight, the goal being to understand the test conditions necessary to reproduce the mechanical (pressure) and thermal (heat flux, temperature) loads acting on the control surface device (extrapolation-from-flight and toflight procedure).

AEROTHERMODYNAMI C DESIGN OF THE EXPERT OPEN FLAP ASSEMBLY PLASMA TEST

The present paper is related to the numerical analyses carried out before the test on the Open Flap Assembly scheduled in the CIRA Plasma Wind Tunnel Scirocco in the frame of the EXPERT pre-ight experimental activities. The aim of the test campaign is to address some technical issues related to scientic objectives of Payload 6, related with the analysis of ow reattachment on the ap due to the shock wave boundary layer interaction, and Payload 8 whose main objective is the measurement of the heat ux in the rear surface of the ap through an infrared camera mounted in the cavity. Additional goals are to consolidate the ground-to-ight extrapolation relations for the characterization of the convective heating on the ap and the reattachment and radiative heating in the cavity. The test article reproduces the EXPERT capsule geometry around the ap and the cavity region; a cylindrical cooled leading edge and lateral rounded edges have been also added in order to allow the mechanical interfacing with the facility model support system. The assessment of typical ow features has been done through two- and three-dimensional numerical computations around the model focusing the attention, in particular, on the eects of wall catalysis, emissivity and wall temperature on the results foreseen during the most energetic test to be performed on the conceived model. An important aspect of the present analysis has regarded the analysis of the coupled aero-thermal environment that is necessary to consider in order to analyze the heating of the cavity under the ap: radiative heating between the ap rear surface and the cavity has been estimated assuming ctitious emissivity coecient to be applied as boundary conditions in the CFD code, and then considering the coupling between the external eld and the internal thermal state within the ap and the cavity.

Shock Wave Boundary Layer Interaction Measurement Assembly on the EXPERT Capsule

In order to improve the level of confidence in the design of one of the most critical technology for re-entry space vehicles, a dedicated flight experiment on the shock wave boundary layer interaction phenomenon to be flown on the EXPERT capsule has been conceived. As matter of fact, the common approach to design a space vehicle is based on ground experimental tests, computational predictions and ground-to-flight extrapolation methodologies even though a modern approach foresees to improve such design tools by validating them with respect to flight experiments. At the moment the lack of hypersonic flight data that can serve as a point of reference for this validation process makes it impossible, especially for some of the most challenging hypersonic problems, as the shock wave boundary layer interaction phenomena that could take place in proximity of a deflected control surface. In the frame of the EXPERT program of the European Space Agency, focused to collect in-flight data on relevant aerothermodynamic phenomena, a certain number of experiments/payloads has been conceived in order to collect flight data for further analysis and comparison with numerical and experimental results. Among the others, the shock wave boundary layer interaction in proximity of two opposite deflected flaps will be analyzed through a dedicated payload in order to consolidate the knowledge on this particular phenomenon. The study of flow separation ahead of the open flap induced by a shock wave boundary layer interaction constitutes payload PL07, currently under investigation: two-symmetrically opposite faces, ahead the 20deg fixed open flaps, will be instrumented with temperature, pressure and heat flux sensors in order to analyze the interaction effects and to characterize the boundary layer approaching the flap. Measurements will be performed along the entire trajectory of representative surface properties to be used to assess the understanding about three dimensional viscous interactions and real gas effects on shock wave boundary layer interaction phenomena in high enthalpy re-entry flow conditions.

PRELIMINARY DESIGN OF A SUB-SCALE BREADBOARD FOR LOx-CH4 COMBUSTION ANALYSIS

regards to liquid oxygenmethane combustion, are currently on going. The main goal of the program is to built and operate a full system demonstrator, class 3 tons, fed by liquid oxygen and liquid methane which becomes gaseous in the regenerative cooling channels. In order to follow an incremental approach in terms of system complexity, suitable design of a small scale breadboard to test critical sub-system components has been performed. The breadboard has been designed in order to investigate manly the characteristics of dierent injectors (either co-axial or swirl) for oxygen-methane combustion at high pressure and their eects on the ame before their use on a full scale engine. The calorimetric design of cooling disks will allow for the characterization of heat ux prole along the combustion chamber for numerical validation. Moreover, for the windowed version, non intrusive optical techniques will be used to investigate the injection, mixing and ame characteristics.

Preliminary Design of a 30kN Paraffin-Based Hybrid Rocket Engine

One of the objectives of the HYPROB program is the development of tools, design and manufacturing methodologies applicable to hybrid systems and the verification of these technological developments through the realization and test of a 30 kN rocket engine. The technological demonstrator is based on nitrous oxide (N2O) as oxidizer and paraffin as propellant and will have most attractive capabilities of hybrid systems compared to solid or liquid engines, as throttability and re-ignition. The project targets to achieve a TRL of enabling technologies for hybrid propulsion equal to 5. The paper reports the study logic defined to achieve the goals of the project and the status of the technical activities related to the preliminary design of the demonstrator, based on a design tool developed ad-hoc.

Numerical and Experimental Analyses on Re-entry Vehicle Control Surfaces

The present paper reports the design, execution and numerical rebuilding of two plasma wind tunnel experimental campaigns carried out with the aim to characterize the behaviour of a deflected control surface in high enthalpy reacting flow conditions. The experimental campaigns have been conceived to reproduce on the control surface the mechanical and thermal loads expected during a re-entry trajectory; in particular, the first campaing was devoted to the analysis of shock wave boundary layer interaction ahead a deflected surface, the aim being to reproduce at ground the same characteristic parameters of the interaction estimated in flight conditions along a re-entry trajectory whereas the second one was devoted to the analysis of the convective heating on the flap and inside the cavity and the radiative heating in the cavity region. Models and test definitions were carried out through a well-established numerical procedure; after the execution of the two experimental campaigns, the wide amount of measurements, acquired through intrusive sensors and optical diagnostic techniques, allowed for the numerical rebuilding of the tests and the comparison between numerical and experimental results.

Design, Execution and Rebuilding of a Plasma Wind Tunnel Test compared with an Advanced Infrared Measurement Technique

AC = Actively Cooled AoA = Angle of Attack ASA = Advanced Structural Assembly ASI = Italian Space Agency CFD = Computational Fluid Dynamics CIRA = Italian Aerospace Research Centre ESA = European Space Agency EXPERT = EXPErimental Re-entry Test bed FCW = Fully Catalytic Wall FRC = Finite Rate Catalysis FLPP = Future Launcher Preparatory Program FTB-X = Flying Test Bed X IR = Infrared MSS = Model Support System NE = Non Equilibrium NS = Navier-Stokes q = Heat Flux PG = Perfect Gas PWT = Plasma Wind Tunnel TAS-I = Thales Alenia Space Italia TPS = Thermal Protection System UHTC = Ultra High Temperature Ceramics