Abstract

The main disadvantage of contact methods of temperature measurement by means of thermocouples is the thermal inertia of a sensitive element, which adds an additional methodological error in the dynamic measurements of temperature. In gas temperature measurement, a researcher deals with approximation of the true temperature. And also, thermocouples have limited range of measured temperature. If the temperature of the object changes with a certain speed, then thermocouple needs time to achieve thermodynamic equilibrium with the object. This time determines the thermocouple reaction rate to incoming temperature change. If the temperature of the object changes at a rate which exceeds the reaction rate of the thermocouple, in this case the thermocouple does not reach the thermodynamic equilibrium with the object of measurement. Thermo EMF of the thermocouple corresponds to the temperature to which the thermocouple sensitive element has heated up, not to the true temperature of the object of measurement. Hence, it is necessary to study the dynamic characteristics of the thermocouple and to develop a method for the temperature values restoration from thermo EMF of the thermocouple in the transient mode of its operation, with relatively low values of the temperature of the sensitive element. The purpose of the article is to improve the method of dynamic temperature measurement by using experimentally obtained dynamic characteristics of the thermocouple to restore the true value of the temperature of the medium based on the methods of solving the inverse measurement problem. The method of determining the gas flow temperature using a thermocouple in the transient mode is considered in the article. The method of nonlinear approximation based on the assumption that the transient characteristic of a thermocouple is the sum of exponentials is applied, and a model of the transient characteristic of a thermocouple is obtained. Applying the deconvolution, the form of the temperature pulse of the gas flow is determined.

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