Calibration uncertainty estimation of a strain-gage external balance

Reis, M. L. C. C.; Castro, R. M.; Mello, Olympio

doi:10.1016/j.measurement.2012.09.016

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…From Strutz (2016), where B is the least squares estimator of B, W j is the weighting matrix for a particular degree of freedom (DOF), j, and the overbar indicates averaged quantities over all calibration runs (five in total). As suggested by Reis et al (2013), the weighting matrix is computed as the sum of the error contributions due to weights and the wire-pulley setup V w , such as misalignments and friction forces, and the variance in the readings of the strain sensors V r . Accordingly, The second term on the RHS of Eq.…”

Section: Static Calibrationmentioning

confidence: 99%

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An alternative floating element design for skin-friction measurement of turbulent wall flows

2018

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Indirect methods to estimate surface shear stress are commonly used to characterise rough-wall boundary-layer flows. The uncertainty is typically large and often insufficient to carry out quantitative analysis, especially for surface roughness where established scaling and similarity laws may not hold. It is, thus, preferable to rely instead on independent measurement techniques to accurately measure skin friction. The floating element was one of the first to be introduced, and still is the most popular for its features. Although its fundamental principle has remained unchanged, different arrangements have been suggested to overcome its inherent limitations. In this paper, we review some of these designs and further present an alternative that is able to correct for extraneous loads into the drag measurement. Its architecture is based on the parallel-shift linkage, and it features custom-built force transducers and a data acquisition system designed to achieve high signal-to-noise ratios. The smooth-wall boundary-layer flow is used as a benchmark to assess the accuracy of this balance. Values of skin-friction coefficient show an agreement with hot-wire anemometry to within 2% for Re = 4 × 10 3 up to 10 4. A rough surface of staggered distributed cubes with large relative height, ∕h ≃ 10 , is also investigated. Results indicate the flow reaches the fully rough regime, at the measurement location, for the entire range of Reynolds number. Furthermore, the values of skin friction agree with existing estimations from alternative methods.

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Section: Static Calibrationmentioning

confidence: 99%

“…Potential errors induced by wire misalignments, friction of the pulley and weight application are all factored into the covariance matrix W j . Further details can be found in Reis et al (2013). u (a+b) amounts to approximately 97% of the total variance at low Re but only 30% at higher values.…”

Section: Contributions (A) and (B)mentioning

confidence: 99%

An alternative floating element design for skin-friction measurement of turbulent wall flows

2018

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“…The main difficulty comes from the fact that operating conditions concerns rarefied regime with low density flows, giving force values estimated between 1mN and 1 N. Aerodynamic balances applied to supersonic wind tunnels are ranged in two main balance groups' internal and external balances. Internal balances [32] are a test model extension and located inside the test section, on the contrary, external [33] are placed outside the test section and the model is supported with thin wires. For the present study, a sting balance was designed to measure drag and lift forces applied to the waveriders in supersonic and hypersonic flows.…”

Section: The Sting Balance Descriptionmentioning

confidence: 99%

Experimental Analysis of Waverider Lift-to-Drag Ratio Measurements in Rarefied and Supersonic Regime

Hugo¹,

Lago²

2022

Hypersonic Vehicles - Applications, Recent Advances, and Perspectives

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This work, performed in the MARHY rarefied hypersonic facility, experimentally explores the effects of rarefaction on a classical waverider geometry. This hypersonic vehicle is designed to develop a shock attached along the leading edge length to improve flight efficiency. The concept was first proposed by Nonweiler in 1959. Since then, many studies have been conducted, mainly on numerical aspects. Few works have included the influence of the viscous effect, we can cite those of Bowcutt who showed how viscous effects impact the optimal shapes due to the skin friction drag. However, the trajectories of these types of vehicles anticipate flights with high Mach numbers and at high altitudes where rarefaction effects can strongly impact the lift-to-drag ratio predictions. This work focuses on the behavior of the L/D ratio at different supersonic operating conditions. The viscous effects were analyzed with 4 operating flow conditions: Mach 2 and 8 Pa static pressure and Mach 4 with 2, 8 and 71 Pa static pressures. For this purpose, the aerodynamic coefficients were measured for several angles of incidence. with a homemade sting balance. The experimental results were compared to Monte Carlo numerical simulations performed with the DS3V code.

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“…As expressed by Belter (1998) at the Boeing Aerodynamics Laboratory, obtaining the precision limit of the force measurements from the balance calibration residuals generally yields the most conservative estimates of repeatability. The other more involved methods of obtaining the balance uncertainty rely on the uncertainties of the curve fitting parameters of the calibration matrix or the goodness of the fit of the leastsquare multivariate regression Reis et al, 2004;Kammeyer and Rueger, 2008;Reis, Castro and Mello, 2013). The application of these methodologies will result in balance uncertainties that depend on the readings of the strain gages during a test (Reis et al, 2002).…”

Section: Validationmentioning

confidence: 99%

Uncertainty Analysis of Test Data at the NRC 1.5-Meter Trisonic Wind Tunnel

Fakhraei

Weiss

2016

32nd AIAA Aerodynamic Measurement Technology and Ground Testing Conference

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Ainsi, tous les efforts d'amélioration de la qualité des données devraient être concentrés sur la balance de la demi-maquette et les instruments de mesure de pression, afin de réduire leurs incertitudes. Les résultats des analyses ont été validés grâce à une méthode alternative de propagation des erreurs ainsi que par la comparaison des incertitudes aléatoires calculées avec la variabilité observée des paramètres de sortie. Cela étant, des estimations plus détaillées des biais et des erreurs de précision dans les mesures de la balance dynamométrique pourraient être bénéfiques à l'algorithme. Mots-clés: analyse d'incertitudes, soufflerie, aérodynamique UNCERTAINTY ANALYSIS OF TEST DATA AT THE NRC 1.5 METER TRISONIC WIND TUNNEL Samin FAKHRAEI ABSTRACTAn uncertainty analysis algorithm has been developed at the National Research Council of Canada (NRC) 1.5 meter trisonic wind tunnel in Ottawa, Ontario, in order to assess the data quality in the half-model experiments carried out by Bombardier Aerospace. The analysis follows the methodology recommended by the AIAA Standard S-071A-1999 to propagate the systematic and random errors in the measured variables through the complete data reduction routine, in order to calculate the overall uncertainties of the tunnel freestream parameters and the key aerodynamic force and moment coefficients in the form of a 95-percent confidence interval. Detailed breakdowns of the total uncertainties have been obtained to separately investigate the systematic and random components, and to identify the variables that have the largest contribution to the uncertainties. With the implementation of the developed algorithm, the uncertainties of the results are precisely quantified at every measurement point throughout an experiment. Hence, the analysis can be performed over a range of test conditions, aircraft model configurations, and angles of attack. The data of the most recent Bombardier experiments have been used to present the outcomes. The analyses reveal that the freestream properties are achieved with high accuracy at the NRC wind tunnel, as the uncertainties in the freestream Mach number and dynamic pressure are respectively limited to 0.4% and 0.7% of the desired nominal values. The uncertainties in the coefficients of lift and drag vary over the pitch sweep during a test due to the functional dependence on the normal and axial force, as well as the angle of attack. The magnitudes and the component breakdowns of the uncertainties in these coefficients also vary with the tunnel operating condition and from one test article to another. Nevertheless, the force and pressure measurements consistently appear to be the dominant contributors. Hence, any attempts to improve the data quality should focus on the half-model balance and the pressure measurement instruments to reduce their uncertainty. The analysis results have been validated through an alternative error propagation methodology, and also by comparing the calculated random uncertainties to the observed variability in the result par...

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Calibration uncertainty estimation of a strain-gage external balance

Cited by 11 publications

References 13 publications

An alternative floating element design for skin-friction measurement of turbulent wall flows

An alternative floating element design for skin-friction measurement of turbulent wall flows

Experimental Analysis of Waverider Lift-to-Drag Ratio Measurements in Rarefied and Supersonic Regime

Uncertainty Analysis of Test Data at the NRC 1.5-Meter Trisonic Wind Tunnel

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