Aerothermal Testing of Ablatives for Material Performance

A review of recently published literature was conducted to provide a general overview on the development of aerothermal testing methods on ablatives for material performance. Specifically, these aerothermal testing methods will revolve around the utilization of the Laser Hardened Materials Evaluation Laboratory (LHMEL), Inductively Coupled Plasma (ICP) torch, and arc-jet test facilities. The purpose of utilizing these methods is to test and characterize ablative materials, which are materials commonly used as sacrificial thermal protection systems (TPS) materials for aerospace industry. For instance, as sacrificial materials, ablative materials allow for the production of propulsion devices, such as liquid and solid rocket motors, or for the protection of vehicles and probes during hypersonic flight through a planetary atmosphere. These materials have a wide range of applications, which is why proper aerothermal testing of these materials for their performance is crucial in evaluating how the ablative materials may be utilized, and what its limits are in terms of properties, such as thermal resistance. This paper summarizes approximately 14 investigations, which represent research that has been conducted within the past 25 years by individuals worldwide knowledgeable of LHMEL, ICP, and arc-jet test facilities used for ablative materials. Applications and background on ablative materials were investigated, as well as the aerothermal testing facilities utilized to characterize their material performance and properties. LHMEL test facilities primarily apply a type of laser testing, ICP test facilities produce plasma jets to induce extreme heat flux conditions, and arc-jets are based on the operation of an arc heater. These testing facilities were studied and explained by researchers as to how they may be applied to assess the material performance of ablative materials. Additionally, the continued development of LHMEL, ICP, and arc-jet testing facilities and improvement to their testing methods was studied.