Heat Flux Reconstruction in a Multimaterial Gauge with Multiple Embedded Temperature Sensors

Abstract

Creating heat flux maps is one of the major data reduction tasks of ground-test hypersonic facilities. The ability to embed multiple high-frequency sensing elements offers improved performance of over other types of heat flux gauges, such as Schmidt-Bolter gauges, when there is significant lateral heat flux, i.e., close to the leading edge of fin elements and wings. Hypersonic flow heat transfer tests with mismatched materials were conducted in a Mach 6 hypersonic facility to demonstrate the ability of embedded-sensor gauges to measure the vector heat flux. A novel algorithm to reconstruct the thermal field in the gauge and extract both the lateral and normal components of the heat flux vector is discussed. The main innovation of this work is a least squares approach to balance the impulse response for mismatched gauge materials. The reconstruction approach is verified using virtual tests carried out with finite element simulations on gauges with different distributions of epoxy and metal. Validation is carried out on hypersonic wind tunnel tests with both matched and mismatched gauge-article materials. The main findings of this research are that the intergauge heat flux that arises due to mismatched materials is important and accounts for more than 10% of the normal heat flux.