Uncertainty Quantification of Turbulence Measurements in a Fully Pulsed Axisymmetric Subsonic Air Jet

Abstract

This paper reports the statistical accuracy evaluation of the implementation of ensemble-averaged equation used for the measurement of turbulence quantities in a fully pulsed, axisymmetric-subsonic air jet issuing into the still surrounding air. A constant mass flow rate and frequency of pulsation were used to generate the intermittent free jet, which physically contained a period of no flow between pulses due to a mechanical excitation. Time-history records of the random process were gained from a single normal hot-wire probe by a digital sampling technique, where the probe was operated in a constant temperature mode and placed at a fixed location in the jet field with the probe stems parallel to the mean flow direction. Within the framework of amplitude-domain analysis, the accuracy assessment was performed to which the uncertainties of mean value and higher-order moments were evaluated from the given values of sampling parameters, where the estimate of integral-time scale of the random process was the basis for determining the given sampling parameters. The present results suggest appropriate values of number of samples, sampling frequency, and sampling time of the hot-wire anemometer (HWA) technique for a repeatable turbulence measurement in the unsteady jet within a high degree of accuracy.