Francesco Panerai

Plasma Wind Tunnel Testing as Support to the Design of Gas-Surface Interaction In-Flight Experiments

This paper describes part of the development activities for two flight experiments dedicated to the study of catalysis phenomena in atmospheric reentry conditions. Two low earth orbit reentry missions of the European Space Agency, EXPERT and IXV, are considered, as gas-surface interaction and catalysis phenomena are design driver parameters for their Thermal Protection Systems. Catalycity discontinuities, due to different materials junctions promote overheating effects along their surfaces, which have to be carefully handled to guarantee a safe heat shielding. The results of test campaigns performed at the von Karman Institute for Fluid Dynamics in such frame are summarized and discussed. They are dedicated to the ground simulation of the catalytic transition phenomenon under different probes configuration.

Catalysis Phenomena Determination in Plasmatron Facility for Flight Experiment Design (Invited)

This article highlights the importance of ground plasma testing in the design and development of flight experiments for atmospheric reentry vehicles. The determination of catalytic properties covers a key role for Thermal Protection Systems, since flight catalysis phenomenon are often a design driver for the heat shield. The results of a test campaign at the von Karman Institute for Fluid Dynamics, in the framework of the European Space Agency EXPERT reentry mission, are presented. They are dedicated to the determination of the catalytic and emissive properties of the ceramic and metallic Thermal Protection Materials selected for the nose and the body-skirt of the EXPERT capsule respectively. During the reentry, the chemistry developing over the vehicle surface due to the different catalycity properties of the two Thermal Protection Materials can promote a temperature jump at their junction. An experimental evidence of such a phenomenon is also provided.

Gas/Surface Interaction Study on Ceramic Matrix Composite Thermal Protection System in the VKI Plasmatron Facility

An experimental campaign dedicated to the characterization of a silicon carbide based thermal protection system is performed in the Plasmatron wind tunnel at the von Karman Institute for Fluid Dynamics. Emissivity, catalycity and oxidation behavior for representative specimens are investigated under a wide set of operating conditions in order to reproduce typical reentry flight situations. Intrusive measurements for flow characterization are used together with infrared techniques and optical emission spectroscopy that provide diagnostic of the test articles surface and the surrounding environment. Experimental data are postprocessed by means of numerical simulations that allow flow enthalpy re building and characterization of the boundary layer chemistry for the different conditions investigated .

Off-Stagnation Point Testing and Methodology in Plasma wind tunnel

Dedicated ground testing is a fundamental requirement for TPS design since nowadays spacecraft, which have stringent mass budget, need more and more precise and specific testing conditions. Plasma wind tunnels are commonly used for the suitable dissociated flow environments they provide for stagnation point testing. This paper explores the capabilities that such facilities could offer also for off-stagnation point testing to complement aerothermodynamic databases. A methodology for simulating reacting boundary layers in offstagnation point conditions is assessed with numerical computations. The VKI Plasmatron facility and the related measurement techniques are presented, for the new testing configuration. The first experimental results are examined to analyze the testing methodology and discuss its relevance for flight extrapolation applications.