Averaging Pitot Tube (Annubar)

             To obtain a better average value of flow, special two-chamber flow tubes with several pressure openings distributed across the stream are available, as shown in Fig. These annular averaging elements are called annubars. They consist of a tube with high- and low pressure holes with fixed separations.

             On a conventional integrated Pitot tube, the alignment can be critical. Misalignment causes errors in static pressure since a port facing slightly upstream is subject to ‘part’ of the stagnation or total pressure. A static port facing slightly downstream is subjected to a slightly reduced pressure.