Parametric assessment of effect of designed-in features on thermal response of thermal protection system materials

Thermal protection systems protect the payload of an entry vehicle from the extreme environment encountered during atmospheric entry. It may be possible to augment the functionality of some thermal protection system materials by adding systems for cooling, sensing, or self-healing. However, the addition of these systems may otherwise impact the nominal functionality of the material. This study aims to examine the impact that embedded designed-in features have on the thermal response of an insulating thermal protection system material. The effect on the thermal response of the material is examined through varying the size, number, and depth of the features. A heat transfer code modeling the thermal conductivity and surface to surface radiation in these materials with designed in features is developed. The presence of a baseline feature results in increased peak bondline temperature and earlier time to peak temperature. Parametric studies of feature depth, size and number indicate increasing depth reduces peak bondline temperature, increasing size increases peak bondline temperature until depth exceeds 1.3", and increasing feature number magnifies the depth and size effects. Additionally, increasing the depth also delays the time that peak bondline temperature occurs.