Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data

Turbulence parameters, in particular integral length scale (ILS) and turbulence intensity (Tu), are key input parameters for various applications in aerodynamics and aeroacoustics. The estimation of these parameters is typically performed using data obtained via hot-wire measurements. On the one han...

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Autores principales:	Luciano Caldas, Carolin Kissner, Maximilian Behn, Ulf Tapken, Robert Meyer
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	turbulence integral length scale hot-wire data analysis turbulence parameter extraction turbomachinery flow turbulence Thermodynamics QC310.15-319 Descriptive and experimental mechanics QC120-168.85
Acceso en línea:	https://doaj.org/article/949bd3b3a80e426fbb24a2be79ed9be0
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id	oai:doaj.org-article:949bd3b3a80e426fbb24a2be79ed9be0
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spelling	oai:doaj.org-article:949bd3b3a80e426fbb24a2be79ed9be02021-11-25T17:31:22ZComparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data10.3390/fluids61103722311-5521https://doaj.org/article/949bd3b3a80e426fbb24a2be79ed9be02021-10-01T00:00:00Zhttps://www.mdpi.com/2311-5521/6/11/372https://doaj.org/toc/2311-5521Turbulence parameters, in particular integral length scale (ILS) and turbulence intensity (Tu), are key input parameters for various applications in aerodynamics and aeroacoustics. The estimation of these parameters is typically performed using data obtained via hot-wire measurements. On the one hand, hot-wire measurements are affected by external disturbances resulting in increased measurement noise. On the other hand, commonly applied turbulence parameter estimators lack in robustness. If not addressed correctly, both issues may impede the accuracy of the turbulence parameter estimation. In this article, a procedure consisting of several signal processing steps is presented to filter non-turbulence related disturbances from the unsteady velocity data. The signal processing techniques comprise time- and frequency-domain approaches. For the turbulence parameter estimation, two different models of the turbulence spectra—the von Kármán model and the Bullen model—are fitted to match the spectrum of the measured data. The results of several parameter estimation techniques are compared. Computational Fluid Dynamics (CFD) data are used to validate the estimation techniques and also to assess the influence of the variation in window size on the estimated parameters. Additionally, hot-wire data from a high-speed fan rig are analyzed. ILS and Tu are assessed at several radial positions for two fan speeds. It is found that most techniques yield similar values for ILS and Tu. The comparison of the fitted spectra with the spectra of the measured data shows a good agreement in most cases provided that a sufficiently fine frequency resolution is applied. The ratio of ILS and Tu of the velocity components in longitudinal and transverse direction allows the assessment of flow-isotropy. Results indicate that the turbulence is anisotropic for the investigated flow fields.Luciano CaldasCarolin KissnerMaximilian BehnUlf TapkenRobert MeyerMDPI AGarticleturbulence integral length scalehot-wire data analysisturbulence parameter extractionturbomachinery flow turbulenceThermodynamicsQC310.15-319Descriptive and experimental mechanicsQC120-168.85ENFluids, Vol 6, Iss 372, p 372 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	turbulence integral length scale hot-wire data analysis turbulence parameter extraction turbomachinery flow turbulence Thermodynamics QC310.15-319 Descriptive and experimental mechanics QC120-168.85
spellingShingle	turbulence integral length scale hot-wire data analysis turbulence parameter extraction turbomachinery flow turbulence Thermodynamics QC310.15-319 Descriptive and experimental mechanics QC120-168.85 Luciano Caldas Carolin Kissner Maximilian Behn Ulf Tapken Robert Meyer Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data
description	Turbulence parameters, in particular integral length scale (ILS) and turbulence intensity (Tu), are key input parameters for various applications in aerodynamics and aeroacoustics. The estimation of these parameters is typically performed using data obtained via hot-wire measurements. On the one hand, hot-wire measurements are affected by external disturbances resulting in increased measurement noise. On the other hand, commonly applied turbulence parameter estimators lack in robustness. If not addressed correctly, both issues may impede the accuracy of the turbulence parameter estimation. In this article, a procedure consisting of several signal processing steps is presented to filter non-turbulence related disturbances from the unsteady velocity data. The signal processing techniques comprise time- and frequency-domain approaches. For the turbulence parameter estimation, two different models of the turbulence spectra—the von Kármán model and the Bullen model—are fitted to match the spectrum of the measured data. The results of several parameter estimation techniques are compared. Computational Fluid Dynamics (CFD) data are used to validate the estimation techniques and also to assess the influence of the variation in window size on the estimated parameters. Additionally, hot-wire data from a high-speed fan rig are analyzed. ILS and Tu are assessed at several radial positions for two fan speeds. It is found that most techniques yield similar values for ILS and Tu. The comparison of the fitted spectra with the spectra of the measured data shows a good agreement in most cases provided that a sufficiently fine frequency resolution is applied. The ratio of ILS and Tu of the velocity components in longitudinal and transverse direction allows the assessment of flow-isotropy. Results indicate that the turbulence is anisotropic for the investigated flow fields.
format	article
author	Luciano Caldas Carolin Kissner Maximilian Behn Ulf Tapken Robert Meyer
author_facet	Luciano Caldas Carolin Kissner Maximilian Behn Ulf Tapken Robert Meyer
author_sort	Luciano Caldas
title	Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data
title_short	Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data
title_full	Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data
title_fullStr	Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data
title_full_unstemmed	Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data
title_sort	comparison of techniques for the estimation of flow parameters of fan inflow turbulence from noisy hot-wire data
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/949bd3b3a80e426fbb24a2be79ed9be0
work_keys_str_mv	AT lucianocaldas comparisonoftechniquesfortheestimationofflowparametersoffaninflowturbulencefromnoisyhotwiredata AT carolinkissner comparisonoftechniquesfortheestimationofflowparametersoffaninflowturbulencefromnoisyhotwiredata AT maximilianbehn comparisonoftechniquesfortheestimationofflowparametersoffaninflowturbulencefromnoisyhotwiredata AT ulftapken comparisonoftechniquesfortheestimationofflowparametersoffaninflowturbulencefromnoisyhotwiredata AT robertmeyer comparisonoftechniquesfortheestimationofflowparametersoffaninflowturbulencefromnoisyhotwiredata
_version_	1718412239026782208

Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data

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