Numerical investigation of pressure measurement by pitot tubes in microscale Taylor–Couette flow with hyper-rotate speed and its correction

As the most classic method in fluid mechanics, pitot tubes have been widely employed to capture gauge pressure. Their effective operation is based on the premise that the measured fluid is ideal, irrotational, and incompressible, and the pitot tubes do not interfere with the measured flow field. However, in microscale Taylor–Couette flow with hyperrotation speed originating from power-to-weight ratio rotating machinery, its correction has never been investigated systematically for the case, in which the scale of the pitot tubes is much larger than the clearance. In this study, the feasibility of using pitot tubes in the measurement of pressure in a microscale Taylor–Couette flow with hyperrotation speed and its correction was considered. First, physical insight into the influence of pitot tubes on shear flow under the scale effect was obtained. The presence of the pitot tubes had less impact on the mean flow field of the shearing flow. In contrast, the sudden expansion induced by the pitot tubes caused additional instability in the shearing flow through the recirculation zone near the connection area. The influence of pitot tubes on the turbulence of the shearing flow is not confined to a local area but extends across the entire clearance between the stator and rotator. Second, the pressure in the clearance cannot fully permeate the cavity where the monitor is located. Therefore, the gauge pressure captured by the pitot tubes is underpredicted in high-pressure while overpredicted in low-pressure regions. The maximum deviation appears near the minimum clearance height. The deviation in the pressure captured by the pitot tubes increases with an increase in the depth and diameter of the pitot tubes, and the influence of the recirculation zone becomes notable. As the clearance height increases, the ratio of the scale in the pitot tubes to the clearance height decreases, degrading the deviation of the pressure captured by the pitot tubes. Within the parametric range studied, the deviation maximum in pressure captured by the pitot tubes is up to 18.5%. Moreover, the pressure captured by the pitot tubes was corrected. The coefficient α, related to the rotational Reynolds number, clearance height, and depth and diameter of the pitot tubes, was deduced. The correction in this study had improved the distribution of pressure, which shows a better agreement.