Assessment of Measurement Uncertainty of Additively Manufactured Multi-Hole Probes

The multi-hole probes are popular tools of velocity measurement, appreciated if the flow direction changes in a wide range. Application of modern manufacturing methods gives a possibility to improve the technical quality of the probe - e.g. minimizing the probe's dimensions or the pressure taps diameter, disturbances from the desired shape etc. This in line, together with the usage of modern measurement equipment and accurate computation methods, allows on diminish the overall measurement uncertainty of such the probe. In the paper the measurement uncertainty of the additively manufactured 5-hole probe has been estimated and discussed. We performed a calibration of the probe designed and manufactured in our team. The results allowed us to estimate the measurement uncertainty of the flow direction. The experiment showed the expanded measurement uncertainty of the angle of 0.36° regardless the flow speed. Analytical estimation proved that the quality of the pressure measurement is more than acceptable and if it were the only source of inaccuracy, the measurement uncertainty would be in range of 0.02° to 0.03° at the speed of 30 m/s, and increment the speed to 70 m/s would reduce this value below 0.01°.