Research and Analysis of Rapidly Changing Gas Flow Temperatures Measurement Methods

Abstract

The temperature of a transducer sensitive element, as a result of its heat capacity, will always lag behind the temperature of the gas flow if this temperature changes. When measuring the flow temperature that varies in time, the transducer doesn't follow the changes in temperature immediately because its sensitive element temperature changes after some time. The distortions of the transducer readings are caused by the thermal inertia due to non-stationary heat processes in the transducers, as well as between transducer and the environment. Since complete elimination of real temperature transducer inertia is not possible, the transducers with some finite values of the thermal inertia are used at practice to measure the varying gas flow temperature. The necessary information about the flow temperature can be obtained by analyzing the record of the non-stationary measurement process. In this case a direct calculation of the flow temperature is made or a correction of the temperature transducer readings delay is made. The results of research and analysis of measurement methods of rapidly changing gas flow temperatures by the direct calculation of the flow temperature and by correcting the temperature transducer readings are presented in this paper.

Methodology for Determining the Response Time of Thermo Transducers for Measuring the Temperature of Gas Flows

“…at a very large value of the coefficient of convective heat transfer. For gas flows, the values are insignificant, although they increase with increase in speed, but do not reach large values [3]. Therefore, the value of the thermal reaction time, determined by the standard method, cannot be judged on the inertial properties of thermo transducer, designed to measure the temperature of the gas stream.…”