Transient temperature probe measurements in a Mach 4 nitrogen jet

Abstract

Stagnation temperature measurements have been obtained in a Mach 4 free jet of nitrogen using a technique based on transient thin film heat flux probe measurements. The uncertainty in the stagnation temperature measurements depends on the probe location within the jet but is typically around ±5 K at the centre of the jet. The thin film heat flux probe technique also provides a measurement of the heat transfer coefficient of the thin film probes with an uncertainty of around ±4% at the centre of the jet. Pitot pressure measurements were also obtained within the jet. Analysis of the heat transfer coefficient results yields the Mach number and velocity profiles which are compared with results from the pitot probe measurements. Jet velocities identified using the thin film probe and the pitot probe techniques produce results with uncertainties of less than ±2% at the centre of the jet. Measurements of RMS stagnation temperature fluctuations indicate values of around 3 K at the centre of the jet to more than 10 K in the shear layer.