Continuously distributed sensors for steady-state temperature profile measurements: main principles and numerical algorithm

Abstract

Principally new method for measurements of steady-state temperature field is suggested. This method is based on the use of so-called continuously distributed sensors (CDS). The basic CDS function is the measurement of temperature profile along the sensor length. The CDS can be manufactured my means of microfilm technologies in the form of a rod, flexible thread, or thin film. Only three electrical cables are needed for connection of CDS and measuring equipment. Nevertheless, it is possible to obtain simultaneously the information about temperature profile at several tens space points along the CDS. So, the CDS is equivalent to several tens of conventional discrete sensors, for example, thermocouples. The measuring process with the use of CDS can be described by the following scheme. A temperature field acts on the CDS causing space non-homogeneity of the electrical parameters of thermo-sensitive films. The space distribution of electrical parameters along CDS can be measured by means of electrical signals of different frequencies. Indeed, the distance to which the electrical signal penetrates the sensor depends on the frequency. So, the measuring impedance of the sensor contains information about space distribution of electrical parameters, which are directly related with the temperature profile. Restoration of the space distribution of electrical parameters from frequency characteristics of the measuring impedance is non-trivial task. From the mathematical point of view it is inverse problem. Some algorithms for solving of this inverse problem are developed and are presented in the paper. Numerical simulations demonstrate possibilities to measure temperature fields by means of CDS.