Heat Transfer Determination in the Arc Heated Facility LBK Using Different Measurement Techniques.

Abstract

Comparative tests were performed on a SiC-sample in the stagnation point configuration of LBK using different pyrometer configurations to demonstrate improved performance of LBK concerning the measurement of surface temperatures with a good accuracy. A pyrometer with miniature optics integrated into the sample holder was successfully qualified for the measurement of the rear surface temperature of the sample. Good agreement was achieved in measured temperatures using both spectral and two color pyrometers. The data on rear surface temperature showed that heat losses from the sample to the sample holder were only a few percent of the total heat flux rate into the sample. Hot wall heat flux rates were determined from the measured surface temperature for radiative equilibrium conditions. Cold wall heat flux rates were determined using a transient heat flux probe and a steady-state calorimeter with water cooling. In order to have a correlation between hot and cold wall heat flux rate tests were performed at the same flow conditions on probes with the same geometry. Since the steady-state calorimeter was developed recently and another nozzle configuration is installed in L2K, comparative heat transfer rate measurements using pyrometer, transient heat flux probe and steady-state calorimeter have been performed at test conditions, which are different from the former one.