The transient transpiration radiometer: analysis and parameter selection

A large variety of available radiometers require steady-state conditions to obtain output results. This means that in order to quantify the heat transfer, the temperature of the instrument must first be stabilised, consequently lengthening its response time. The purpose of this paper is to present a formulation of the transient response of a transpiration radiometer. The measurement technique of the radiometer under study is based on a porous disc aligned perpendicularly to a flowing gas stream, while one of its faces is exposed to the heat flux to be measured. A discussion of the results is presented using a mathematical model, according to an examination of the simplifying assumptions made in the data reduction process and the examination of the response. Also presented are sensitivity analysis, temperature, heat flux intensity and manufacturing constraints of the relevant design.