Design and development of thin wire sensor for transient temperature measurement

[Display omitted] •The developed sensor is a low cost sensor to measure unsteady heat release.•The developed sensor is able to capture temperature fluctuation in presence of thermo-acoustic instabilities.•The developed sensor is free from thermal inertia effect, which improves the sensitivity.•The developed sensor shows the linearity over a wide range of temperature. The temperature measurement is an important parameter in industrial process equipments. Various techniques were developed to measure the transient temperature of the fluid and the solid surface. The precise and accurate measurement of transient fluid temperature is also important in combustors of various power producing devices. During the combustion process in the combustor, when the coupling between heat release and pressure fluctuations takes place, thermo-acoustic instabilities are developed. These instabilities have adverse effect on the combustor. For predicting the instabilities Rayleigh index is very much essential, which can be estimated from unsteady heat release and pressure fluctuation measurement. In this study, the development of sensor, based on hot wire method, to measure unsteady heat release in combustion chamber is presented. For transient heat release measurement, fast response of a sensor is very much important. For fast response, the wire diameter of probe should be as small as possible. To develop a sensor, wire of different diameters and materials are used as probe materials. The stainless steel wire is used as prongs. The constructed sensor is kept in one of the arm of Wheatstone bridge to measure the resistance of sensor. For this NI LabVIEW software and NI-DAQ 6211 is used. From different results, it is observed that the resistance of sensor varies linearly with rise in temperature. The plunge test method is used to measure the response time of sensors. A 0.1 mm Pt wire sensor is checked for different diameter of SS prongs i.e. 0.5, 0.55 and 0.9 mm. A modified 0.1 mm Pt wire sensor with 0.5 mm SS prongs has response time of 50 ms, which is calibrated using FLUKE-9144 bath-tub from 0 °C to 500 °C temperature. Then it is tested in combustion chamber to measure unsteady temperature, in the presence of thermo-acoustic instability with J-Type thermocouple and variation in measured temperature was found to be 8.11%.