Heat transfer measurements of a re-entry capsule using fast response thermocouples

Abstract

Predicting the heat transfer of a re-entry capsule as it enters the atmosphere is critical to the capsule design. At hypersonic speeds, air temperature in front of a capsule entering the Mars atmosphere is heated to about 1600C by friction between the capsule and the gas in the atmosphere. An accurate heat transfer prediction is essential to design the heat shield as light as possible so that the scientific payload can be increased. This project aims to investigate the application of fast response thermocouples to the measurement of heat transfer in the hypersonic flow produced by the gun tunnel, and obtaining representative data on selected re-entry capsule geometries for comparison with theory and other experiments. E-Type thermocouples are used to calculate temperature change by measuring the emf produced by the Seebeck effect. Heat transfer is calculated by assuming one- dimensional heat conduction. This project demonstrates that E-type thermocouples can be designed and constructed to effectively measure temperature with a response fast enough to effectively calculate heat flux during a 20 millisecond gun tunnel run.