Thermo Structural Study of Carbon Phenolic Nose Cap of a Re-Entry Module — Theoretical Evaluation and Flight Performance

ABSTRACT

Aero thermodynamics of reentry modules and development of Thermal Protection System (TPS) for the module are two major areas associated with re-entry flight. For a re-entry flight of a typical module, Carbon Phenolic (CP) ablative nose cap with random ply orientation for nose plug and rosette ply orientation for shell liner was used as TPS. During re-entry, the Forward Base Structure (FBS) is subjected to thermal and pressure loads below CP. Heat flux on the re-entry module nose cap is evaluated using equilibrium air properties and is validated with CFD data at critical trajectory points. TPS is designed to control the temperature of the structure during the entire flight regime. Finite element thermal analysis has been carried out for evaluating temperature distribution to study the thermo structural response of the re-entry nose cap.

During the flight, the recorded temperature in the nose cap is found to be in reasonably good agreement with the thermal analysis results in the plug and shell regions. Using the computed temperature distribution, thermo-structural analysis has been carried out to estimate the strains for comparison of the recorded strains during the flight. Fairly good comparison is seen between the estimated and recorded strains in the nose cap region. This study has validated the methods used for heat flux estimation, finite element modelling for generation of the temperature distribution and the thermo structural integrity assessment on the Carbon Phenolic ablative nose cap for a re-entry mission.

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