Characteristic Analysis Of Heat Fluxgauges Based On High Thermal Conductivity Graphite

Heat flux gauges were essential device for determining heat flux in the domain of aeronautics and astronautics and scientific study. The typical circular foil heat flux gauges had many advantages especially in the aspects like the measuring accuracy, the response velocity and the mature fabrication technology, but it was limited by its applicable temperature. A new heat flux gauges based on the high thermal conductivity graphite were investigated,which used the graphite’s thermostability and anisotropic character that suitable for the gauges.To achieve the demand for measuring, structure material,thermocouples and material for isolation were selected firstly, advanced structure of heat flux gauges were proposed. And based that, the heat conduction equation in the steady state or transient state for the sensitive element, using Maclaurin series solution, were derived to an explicit expression, so the relation between irradiation and temperature difference were developed.The influential factors to index the effect of heat flux were analyzed. The methods, process control and programs for parameterized modeling and optimization design used Abaqus based on Python were introduced, then the best structure dimension parameters were attained in the consideration of the max temperature,temperature difference between the up surface and the down surface, temperature difference across the down surface,the velocity of temperature rising.According to the optimization results, the steady-state situation was analyzed using the finite element method. The heat flux measuring rang and the measuring derivation were achieved. The impossible lowest time and boundary value of heat flux to be determined of the pulse heat flux were deduced through evaluating the heat response time and the sensitivity. The results were modified partially through assessing the influence of the thickness of the graphite material and the thermocouples.To achieve the transient response character of heat flux gauges under the different types of irradiation, the variation trend of the temperature difference on the backside and the output heat flux under constants q and changed q were determined. The results indicated that they showed great agree with the variation trend of the input heat flux and accomplished the design targets in the measuring accuracy and response velocity and so on.