Uncertainty Analysis of Laser-Doppler-Velocimetry Measurements fin a Swirling Flowfield
A statistical analysis of instantaneous laser-Doppler-velocimetry (LDV) measurements acquired in a swirling flowfield is performed. Instrument uncertainties associated with each velocity realization propagate into the ensemble statistics. Integral quantities such as the integrated mass flow rate and swirl number are susceptible to precision uncertainties associated with the instrument's optics, lasers, and electronics. In this study, experimental data are used in conjunction with an analytical model to determine the precision uncertainty of the first three velocity moments. With this analysis, the effects of ensemble size and probe volume location within the flowfield are accounted for. The statistical model is applied to LDV data acquired downstream of an aircraft engine combustor swirler. We show that the precision uncertainties associated with these swirler measurements bound the amount of information that can be extracted from the profiles.