Layered heat flux gauges for aeroentry application

Abstract

A layered heat flux gauge, which can withstand a high temperature environment for applications such as for use on thermal protection shields on aeroentry vehicles, is analyzed, designed, fabricated, and tested. The heat flux gauge consists of two resistance temperature detectors on the top and bottom faces of a thin ceramic substrate. The heat flux is calculated from temperature measurements of the two temperature detectors. An analytical model is used to simulate the gauge response. Several numerical methods to calculate the heat flux are investigated to improve the time response of the gauge. The error due to gauge intrusiveness and the validity of one-dimensional heat transfer within the gauge is studied by solving a steady state two-dimensional composite problem using a semi-analytical approach. Gauge fabrication techniques and measurement devices are discussed. Testing apparatus, including a "close-to-entry" condition apparatus using an arcjet at low pressure and a conduction calibration furnace, are explained. Experimental data showing qualitative gauge response is presented.