6.1 Conclusions and future work
  1. Challenges associated with replicating heat shield re-entry temperatures using Joule heating has been discussed using a prototype of the Orion-MPCV.
  2. Thermal diffusivities of tungsten and graphite materials play a significant role in the temperature distribution field along the entire heat shield. The temperature irregularity zone is due to the heat sinking effect of tungsten material, however the temperature irregularities tries to regulate as temperature contours move further away from the stagnation region.
  3. Coupling prototype heat shield with cylindrical tungsten rod of diameter 8-10mm at a current rating of 600-800A gives the best temperature distribution field to a maximum of 1700K which is lesser than re-entry temperatures of the Orion-MPCV.
  4. The heat shield used had a 50mm diameter and 2mm thickness. However, the 2mm thickness was too small to produce any temperature deviation in the stagnation line within temperature irregularity zone.
  5. Future work should aim at optimising the model (heat shield plus electrical connections) that will enable heat shield to attain temperatures up to 3000K for re-entry applications. This can be done by optimising material thickness through series of simulation. Also the cooling effect at the tungsten/graphite junction has to be carefully investigated.