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Lookup NU author(s): Dr Barry Wise,
Dr Neal Gallagher,
Professor Elaine Martin
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Various applied physics lines of research on the interactions between electromagnetics and flowing water have led to the suggestion that it might be possible to reduce pipeline wall friction by applying a transverse electromagnetic field (EMF). We here conduct a feasibility study of the shape and magnitude of internal fluid flow velocity profiles of hydropower turbine inlet pipelines, with and without an EMF. The flow velocity profile itself can only be measured in transparent pipeline sections with the aid of refined laser velocimetric equipment, which can never be employed in realistic hydropower settings however. The objective of the present studies is therefore to use a much simpler alternative, i.e. an acoustic chemometric approach, relying on 'clamp-on' acoustic sensors applied directly to the outer wall of the pipeline. Our results show that it is fully possible to verify the 'on/off' status of the applied EMF using either of the alternative modalities, laser velocimetry and acoustic chemometrics, i.e. to verify an increased water flux when the EMF is 'on'. The interactions between this feature and realistic changing temperatures (15-27 °C) as well as varying overall water velocities (1-4 m s-1) are explored. It is concluded that the temperature sensitivities of both modalities can be compensated for and, furthermore, that the temperature-compensated modelling is velocity-invariant. This opens up an interesting avenue for field on-line EMF-induced wall friction reduction monitoring and control. Our final feasibility demonstration concerns direct PLS2 intercalibration of the acoustic chemometric monitoring data (X) with the laser velocimetric reference profiles (Y). This translates into a new acoustic chemometric possibility for 'seeing' the effects of the EMF-modified velocity profiles directly from the suitably calibrated acoustic signals alone. We find that a 42-Y-variable PLS2 model can be validated as X, Y: 30%, 70% respectively, fully satisfactory for prediction purposes of the velocity in an outer (near-wall) 5-6 mm annular flow regimen. With this we have positive proof that acoustic chemometric monitoring can be used for predicting the effects of the EMF. Upscaling to field-scale pipelines remains. © 2001 John Wiley & Sons, Ltd.
Author(s): Wise BM, Gallagher NB, Martin EB
Publication type: Article
Publication status: Published
Journal: Journal of Chemometrics
ISSN (print): 0886-9383
ISSN (electronic): 1099-128X
Publisher: John Wiley & Sons Ltd.
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