Characteristic Curves of Iridium-Rhodium Sensing Elements in High-Temperature Transducer Applications

Abstract

In order to increase the capacity and efficiency factor of gas turbines and internal combustion engines while preserving their high reliability, the gas temperature and its distribution need to be measured in combustion chambers. Values of these temperatures can exceed 1800°С in an oxidizing atmosphere. Therefore, designing temperature transducers for measurements in such severe environments, special attention should be paid to the selection of thermometric materials. The requirements of the necessary accuracy and temperature range over 1800°С in an oxidizing atmosphere are fulfilled only by the temperature transducer based on iridium-rhodium alloys. The characteristic curve of such sensing elements is individual and each temperature transducer is to be calibrated. The paper discusses a technique of determining the individual characteristic curve of iridium-rhodium sensing elements of high-temperature transducers. The preparation steps to be taken prior to the calibration and the main stages of determining the characteristic curve are described. The general view of the experimental set for calibrating the sensing elements is presented. Based on the calibration results, the form of approximating polynomial of the individual characteristic curve is proposed.