Arc-Jet Testing on HfB - TaSi Models: Effect of the Geometry on the Aerothermal Behaviour



A. Di Maso1, R. Savino*, 1, M. De Stefano Fumo1, L. Silvestroni2, D. Sciti2
1 Dipartimento di Ingegneria Aerospaziale, University of Naples “Federico II”, P.le V. Tecchio 80, 80125 Naples, Italy
2 ISTEC, Institute of Science and Technology for Ceramics, CNR, Via Granarolo 64, 48018 Faenza, Italy


© 2010 Di Maso et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Dipartimento di Ingegneria Aerospaziale, University of Naples “Federico II”, P.le V. Tecchio 80, 80125 Naples, Italy; Tel: 00390817683360; Fax: 00390817682351; E-mail: raffaele.savino@unina.it


Abstract

Arc-jet experiments in high enthalpy hypersonic (Mach 3) non equilibrium flow were carried out on a HfB2 composite with addition of 15 vol% TaSi2, at temperatures exceeding 2000 K. The aerothermal behaviour was tested considering models having two different geometries, i.e. hemispheric and cone-shaped. The surface temperature and emissivity of the material were evaluated during the tests. Numerical computations of the nozzle flow were carried out in order to identify the flow conditions around the model and to analyze the details of thermal heating. The chemicalphysical modifications were analysed after exposures. The surface emissivity changed from 0.85 to 0.5 due to surface oxidation. The maximum temperatures reached on the tip were strongly dependent on the sample geometry, being around 2300 K for the hemisphere and 2800 K for the cone. Post test SEM analyses confirmed an excellent stability for this HfB2-based material.

Keywords: High enthalpy flow, ceramics, structural composites, high temperature testing, SEM micrography, thermal protection systems.