Determination of the effusivity of different scratched coaxial temperature sensors under hypersonic flow

Abstract

This paper presents an experimental method for determining the effusivity values of different scratched coaxial temperature sensors. These sensors have a response time on the order of microseconds (50 μs) with a rise time of less than 0.3 μs. Two types of scratch were used, mainly abrasive papers with different grit sizes and scalpel blades with different thicknesses to form the sensor junctions. The effect of the scratch technique on the sensor's effusivity is also investigated. The sensors were tested and calibrated in the test section of a shock-tube facility at different operating conditions. It was observed that the effusivity of a particular sensor depends on the Mach number, scratch technique, scratch direction, junction location, as well as on the enthalpy condition. It was also noticed that a scratched sensor using the scalpel blade technique does not require an individual calibration. However, for a sensor scratched using the abrasive paper technique, a calibration for each sensor is likely to be required. The present results have provided useful and practical data of the effusivity values for different scratched temperature sensors. These data are beneficial to experimentalists in the field, and can be used for accurate transient heat transfer rate measurements. © 2010 Springer Science+Business Media, LLC.