High-temperature Reusable Surface Insulation Research Articles

Ablative Heating Technology in Hypersonic Re-entry Vehicles and Cruise Aircrafts

The aim of researches conducted in thermal protection systems in aeronautics and astronautics field of engineering is to generally defend the craft from high heat loads during operation while operating at hypersonic regimes in air and space. The motive of the following composition is to draft a review analysis on ablative heating materials as thermal protective equipment on reusable planetary/atmospheric re-entry vehicles such as a space shuttle, an inter-continental ballistic missile, or a hypersonic cruise missile. The heat liberation can cause much damage to the aircraft/spacecraft whilst operation which is generally beyond repair. It is therefore of utmost importance to research multiple strategy to reduce the effect of shockwaves damage to spacecraft/aircraft materials. We shall initiate the analysis by mentioning some re-usable tile thermal protection system types such as high temperature reusable surface insulation tiles (H.R.S.I), fibrous refectory composite insulation tiles (F.R.C.I), low temperature reusable surface insulation tiles (L.R.S.I) and gradually move on to ablative thermal protection systems with the advent of reinforced carbon-carbon’s application in astronautics and aeronautics respectively.

Failure analysis of a thermal tile on the space shuttle Columbia

Several high-temperature reusable surface insulation (HRSI) tiles from the space shuttle Columbia were analyzed for their response to the catastrophic events during re-entry. The analysis of the HRSI tile focused on the outer surface, which was composed of silica tile with a reaction-cured glass (RCG) coating, and the inner surface strain isolation pad, which is bonded to the tile using a room-temperature vulcanizing silicone adhesive. Light optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to evaluate the tile surfaces. The tiles were found to have a heavily damaged outer surface, with much of the top RCG coating eroded by impact from shuttle debris and/or plasma flow during the shuttle’s breakup and re-entry. The RCG experienced slumping and the silica exhibited melting and glassification due to temperatures exceeding the glass transition temperature and the anticipated tile operating temperatures. Deep cavities present in the material were found to contain metal particles that are not normally present and suggest impact with shuttle debris. Silicone adhesive degradation was also found. The slumping of the silica, the degraded adhesive, and the erosion of the tile contributed to a complex process during which the individual tile delaminated from the shuttle airframe.

Comparison of kinetic models for atom recombination on high-temperature reusable surface insulation

Five kinetic models are compared for their ability to predict recombination coefficients for oxygen and nitrogen atoms over high-temperature reusable surface insulation (HRSI). Four of the models are derived using Rideal-Eley or Langmuir-Hinshelwood catalytic mechanisms to describe the reaction sequence. The fifth model is an empirical expression that offers certain features unattainable through mechanistic description. The results showed that a four-parameter model, with temperature as the only variable, works best with data currently available. The model describes recombination coefficients for oxygen and nitrogen atoms for temperatures from 300 to 1800 K. Kinetic models, with atom concentrations, demonstrate the influence of atom concentration on recombination coefficients. These models can be used for the prediction of heating rates due to catalytic recombination during re-entry or aerobraking maneuvers. The work further demonstrates a requirement for more recombination experiments in the temperature ranges of 300-1000 K, and 1500-1850 K, with deliberate concentration variation to verify model requirements.