TY - JOUR

T1 - Pneumatic-Probe Measurement Errors Causedby Fluctuating Flow Angles

AU - Coull, John D.

AU - Ng, Henry C.H.

AU - Dickens, Tony

AU - Serna, José

AU - Cengiz, Kenan

N1 - Funding Information: The authors would like to thank Rolls-Royce for funding and permission to publish, with particular thanks to Raul Vazquez and Duncan Simpson. Luca di Mare, University of Oxford, provided advice on the unsteady Reynolds-averaged Navier–Stokes calculation setup. Sam Grimshaw of the Whittle Laboratory, University of Cambridge, provided a sample calibration map.

PY - 2023/7

Y1 - 2023/7

N2 - Pneumatic probes such as five-hole probes (5HP) can conveniently measure three-dimensional flow angles, plus total and static pressure. In most applications, transducers are connected using pneumatic tubes, allowing the probe head to be highly miniaturized and robust. However, such “steady” probes are often used in unsteady flows, where they measure a pneumatically averaged flowfield that can differ from the time mean. To better understand these pneumatic averaging effects, an analytical framework is constructed using a quasi-steady model. Total and static pressure coefficients have a symmetric response to both positive and negative incidence.When incidence fluctuates, there is therefore a bias in the pneumatic average. These errors are evident in a shedding wake experiment, where a 5HP overestimates total pressure loss by up to 44% compared to a Kiel probe. These effects can be predicted by coupling an unsteady Reynolds-averaged Navier–Stokes calculation with the quasi-steady model. By predicting pneumatic averaging errors, the quasi-steady model can be used to obtain like-for-like validation of calculations against experimental data. Measurement data can also be corrected, provided that flow angle fluctuations can be measured or estimated. This approach can be readily used to postcorrect the large body of historical data likely to have been corrupted by pneumatic-averaging errors.

AB - Pneumatic probes such as five-hole probes (5HP) can conveniently measure three-dimensional flow angles, plus total and static pressure. In most applications, transducers are connected using pneumatic tubes, allowing the probe head to be highly miniaturized and robust. However, such “steady” probes are often used in unsteady flows, where they measure a pneumatically averaged flowfield that can differ from the time mean. To better understand these pneumatic averaging effects, an analytical framework is constructed using a quasi-steady model. Total and static pressure coefficients have a symmetric response to both positive and negative incidence.When incidence fluctuates, there is therefore a bias in the pneumatic average. These errors are evident in a shedding wake experiment, where a 5HP overestimates total pressure loss by up to 44% compared to a Kiel probe. These effects can be predicted by coupling an unsteady Reynolds-averaged Navier–Stokes calculation with the quasi-steady model. By predicting pneumatic averaging errors, the quasi-steady model can be used to obtain like-for-like validation of calculations against experimental data. Measurement data can also be corrected, provided that flow angle fluctuations can be measured or estimated. This approach can be readily used to postcorrect the large body of historical data likely to have been corrupted by pneumatic-averaging errors.

UR - http://www.scopus.com/inward/record.url?scp=85175425689&partnerID=8YFLogxK

U2 - 10.2514/1.J062569

DO - 10.2514/1.J062569

M3 - Article

AN - SCOPUS:85175425689

VL - 61

SP - 2922

EP - 2931

JO - AIAA journal

JF - AIAA journal

SN - 0001-1452

IS - 7

ER -