This paper presents an analytical approach to quantify the uncertainty of velocity-, angle- and turbulence intensity measurements obtained by hot-wire anemometry. Based on the given results of the model, the paper points out the most critical parameters influencing the quality of the flow measurement.
The proposed approach is divided into three subsections, each accounting for the uncertainties due to the measurement equipment, probe calibration and measurements in the test-rig respectively. For every subsection the propagation of uncertainties is stated in the form of analytical formulas starting with the measurands, e.g. voltage, pressure, temperature, and ending with velocity, angle and turbulence intensity. The approach is applied to data, obtained by a triple hot-wire probe, on two-dimensional traverses in a 1.5-stage cold air turbine. The calibration process and, in particular, the temperature and pressure deviation between calibration and measurement are identified as having a major impact on the measurement uncertainty. With respect to the Aachen test-rig the uncertainty in velocity measurements is lower than 3.5%. The investigation of the turbulence intensity uncertainty yields an increase in uncertainty with increasing turbulence intensity but an insensitivity towards pitch- and yaw-angle uncertainty.