Correlation Equations for Segmented Arc Heaters.

Abstract

Segmented arc heaters are very useful tools for the qualification of TPS materials for re-entry vehicles. The working gas is heated to high temperatures at which high temperature effects like dissociation, ionization, etc. play an important role. The operation of such facilities is sophisticated and requires special care. In order to decrease the number of calibration tests, i.e. the operation costs, correlation relations between the arc heater parameters have been developed by the AEDC technology group. The theoretical model is based on use of dimensionless groupings of variables which reflect the fundamental physics of the arc process. Using these dimensionless groupings instead of individual dimensional variables allows that fundamental arc and flow physics relationships can be locked into these groupings. This may allow more accurate extrapolation over large ranges in physical size. The data base of AEDC consists of parameters of high pressure arc heaters. First attempts have been made to apply the correlation equations resulting from AEDC data base to the L3K segmented arc heater which is operated at remarkably lower pressure levels. First results indicate that additional physical parameters have to be included in the theoretical model to extend the applicability of the model to low pressure arc heaters.