New technique for the fabrication of miniature thin film heat flux gauges

Abstract

This paper details the improvements made to the design and fabrication of thin-film heat flux gauges at Oxford. These improvements have been driven by the desire to improve measurement accuracy and resolution in short duration wind-tunnel experiments. A thin-film heat flux gauge (TFHFG) measures heat flux by recording the temperature history of thin film resistive temperature sensors sputtered onto an insulating substrate. The heat flux can then be calculated using Fourier’s law of heat conduction. A new fabrication process utilising technology from the manufacture of flexible printed circuit boards is outlined, which enables the production of significantly smaller and more robust gauges than those previously used.

Unsteady Phenomena at the Combustor-Turbine Interface

“…Fundamental operating principles of thin film gauges are given by Epstein [30]. Thin film gauges were manufactured with a technique similar to that of Collins [31]. Data processing was performed to calculate heat transfer coefficients using the techniques of Oldfield [32].…”

Development of a Vertically Configured MEMS Heat Flux Sensor

“…Despite the technical benefits of direct heat flux measurement in a wide range of applications, HFSs are employed relatively rarely in the industry, and are currently largely limited to research applications [4]. Instead of using discrete HFS elements, the transfer rate of heat is typically calculated based on one or more temperature measurements [2], [11]. According to [4], the scarce popularity of discrete HFSs is most likely a result of the relatively high cost and challenging manufacturability, as well as the low awareness of the capabilities of the technology.…”

“…Heat flux is commonly measured indirectly by monitoring the effects of heat conduction in a medium with known characteristics of thermal conduction [13]. This can be done by applying a differential temperature measurement across a thermal resistance layer and calculating the heat transfer rate based on Fourier's law [11]. In practice, this can be accomplished with application-specific surface-mounted heat flux sensor plates, which incorporate a differential temperature measurement and a heat resistance layer in one calibrated package [11].…”

“…This can be done by applying a differential temperature measurement across a thermal resistance layer and calculating the heat transfer rate based on Fourier's law [11]. In practice, this can be accomplished with application-specific surface-mounted heat flux sensor plates, which incorporate a differential temperature measurement and a heat resistance layer in one calibrated package [11]. However, this approach requires knowing the thermal conductivity of the heat resistance layer very precisely [1].…”

Development of a Fast-Response Diamond Calorimeter Heat Transfer Gauge

“…temperature (α R ) for the RTD in each DHTG was found using the calibration process described by Collins [24]. from Ref.…”