Five-hole probes are widely used in turbomachinery applications and became a standard device for determining losses in three dimensional flow fields. Traditionally, five-hole probes are manufactured by conventional machining, and an individual and expensive calibration is necessary for their use. By means of additive manufacturing it is now possible to produce probes with rather high quality at low cost, and the high reproducibility of such parts can be utilized to save calibration efforts. This concept was recently turned into reality by Hall and Povey who developed and proposed an open access five-hole probe, the so-called Oxford-probe (see, for instance, Meas. Sci. Technol. 28 (2017)). In many low-speed applications, this open-access method allows results of comparable accuracy to well-calibrated conventional probes.

In general, the effect of Reynolds number on the performance of five-hole probes results in some limitations. It was found that the Reynolds number sensitivity of the Oxford-probe remains small if a sufficient large Reynolds number is chosen. However, especially in low-speed applications, this Reynolds number criterion might be violated in many situations, and further efforts to include Reynolds number effects might be necessary. In literature, relatively less is reported about the underlying mechanisms of Reynolds number effects. In order to close this gap, detailed flow field and Reynolds number effect investigations were conducted employing large-scale models of the Oxford-probe in both wind and water tunnels. By means of comprehensive PIV-measurements in a water tunnel and corresponding oil-flow visualizations, the complex flow dynamics including flow separation and re-attachment were identified. It was found that even in the case of low yaw or pitch angles the pressure coefficient distribution was rather sensitive to the Reynolds number within the low-Re regime. Interestingly, the flow separation and re-attachment at the far-downstream region affected significantly the performance of the probe, too. By means of an independent verification study of the open-access calibration maps, the accuracy and the effect of the Reynolds number was assessed and compared with well-calibrated conventional probes.

Based on the available data and the new flow measurements, a rather user-friendly compact probe device was developed. This compact device includes also an efficient signal processing algorithm, and the end user can directly get all relevant flow quantities without the need of calibration or further data reduction.


Effect of Reynolds Number on Five-Hole Probe Performance: Experimental Study of the Open-Access Oxford Probe

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

Turbo Expo - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.