Laser-based Calibration and Processing Technique for a Robust Fast-Response Surface Heat Transfer Gauge

Abstract

Two methods for calculating surface heat transfer rates from sub-surface temperature measurements are detailed for a robust fast-response gauge, designed for use in high enthalpy hypersonic ground test facilities. One method treats the gauge as a calorimeter, and the second is a pseudo non-linear version of the Sequential Function Specification Method algorithm, which calculates surface heat transfer by deconvolving the unit impulse response of the gauge out of a measured temperature. An experiment to find the impulse response of the gauge using a short duration pulsed laser to apply a heat flux to the surface of the gauge is performed. The response at three initial temperatures is recorded to characterise variation in thermal properties as a function of temperature. The use of the experimentally determined unit impulse response in the calculation of surface heat transfer can significantly reduce measurement uncertainty by removing the need to assume physical geometry and material properties of the gauge.