Preliminary study on the thermal insulation of a multilayer passive thermal protection system with carbon-phenolic composites in a combustion chamber

This paper is a case study on a thermal protection system in a combustion chamber of a ramjet. A multilayer passive thermal protection system (MPTPS) with carbon-phenolic material was established, and the temperature distribution and insulation performance of MPTPS were studied. The problem is that the carbon-phenolic material is pyrolyzed when subjected to high temperatures, leading to the changes in its thermal properties (e.g., density, specific heat capacity, and thermal conductivity.). Moreover, the carbon-phenolic material absorbs heat during the pyrolysis procedure of phenolic resin. Therefore, in this paper, several experimental studies were conducted on carbon-phenolic composites to investigate its pyrolysis characteristics, including tube furnace heating experiment and Py-GC-MS experiment. On the other hand, a one-dimensional multilayer transient heat conduction approach was developed, many calculations were numerically performed to study the effects of negative heat sources and the thickness of carbon-phenolic composites on the thermal insulation performance of MPTPS. As a result, the carbon-phenolic material was pyrolyzed from 200 °C, and the mass-loss rate was 25% when the heating temperature increased up to 900 °C; the negative heat source delayed the temperature rising point and decreased the outer wall temperature; the thickness of the carbon-phenolic composites affected the final outer wall mainly by conduction.