Ferraiuolo, Roberta (2023) Design and assessment of experimental and numerical characterization of a three-blade horizontal axis hydrokinetic water turbine (HAHWT) in a low-velocity channel. [Tesi di dottorato]
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Tipologia del documento: | Tesi di dottorato |
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Lingua: | English |
Titolo: | Design and assessment of experimental and numerical characterization of a three-blade horizontal axis hydrokinetic water turbine (HAHWT) in a low-velocity channel |
Autori: | Autore Email Ferraiuolo, Roberta roberta.ferraiuolo@unina.it |
Data: | 17 Ottobre 2023 |
Numero di pagine: | 261 |
Istituzione: | Università degli Studi di Napoli Federico II |
Dipartimento: | Ingegneria Civile, Edile e Ambientale |
Dottorato: | Ingegneria dei sistemi civili |
Ciclo di dottorato: | 35 |
Coordinatore del Corso di dottorato: | nome email Papola, Andrea papola@unina.it |
Tutor: | nome email Giugni, Maurizio [non definito] Del Giudice, Giuseppe [non definito] Álvarez Álvarez, Eduardo [non definito] Sorgente degli Uberti, Gianluca [non definito] |
Data: | 17 Ottobre 2023 |
Numero di pagine: | 261 |
Parole chiave: | Energy Recovery; Horizontal Axis Hydrokinetic Water Turbine (HAHWT); Pico-Hydro Generation; CFD Model; Experimental Performance Curves; 3D printed; Prototype Design. |
Settori scientifico-disciplinari del MIUR: | Area 08 - Ingegneria civile e Architettura > ICAR/01 - Idraulica Area 08 - Ingegneria civile e Architettura > ICAR/02 - Costruzioni idrauliche e marittime e idrologia Area 09 - Ingegneria industriale e dell'informazione > ING-IND/09 - Sistemi per l'energia e l'ambiente |
Depositato il: | 13 Ott 2023 12:57 |
Ultima modifica: | 09 Apr 2025 13:21 |
URI: | http://www.fedoa.unina.it/id/eprint/14992 |
Abstract
Climate change is impacting, even more, our daily life and our society. Moreover, this terrible increment in droughts, flash floods, land floods, and temperatures has a different impact according to the vulnerability of the considered geographic area. Therefore, this situation represents an opportunity to provide more sustainable energy solutions, especially for undeveloped countries with more climate change consequences. To this end, the present research deals with water energy recovery using a three-blade horizontal axis hydro-kinetic water turbine (HAHWT). Expressly, the turbine model characterization has been provided experimentally, and then these results were used to calibrate a 3D Multi-phase CFD Model. The hydrokinetic turbines have attracted significant interest in the last decades, due to their simple design and low initial investment costs. As a result, it is becoming suitable for pico-hydro generation in rural communities non-connected to electricity services, not requiring additional infrastructures to be built. Hence, for this specific case study, the employed blade profile is an Eppler818, preliminarily studied through Q-Blade software according to the velocity range presumed in the experiments, considering the limitations of the future laboratory set-up in which the prototype would have been tested. The Q-Blade software has allowed a preliminary understanding of the main hydrodynamic forces acting on the hydrofoil. Furthermore, the same software has helped design the prototype blade’s geometry. As the first step, a simplified 2D Computational Fluid Dynamics (CFD) Model has been implemented, starting from the basic bidimensional aerodynamic model: the Linear Momentum Actuator Disk Theory (LMADT). This model has been released due to the auxiliary of the commercial ANSYS ® Fluent ™ code in a Steady State condition. This CFD model has allowed to simulate several external domains to investigate preliminary, the Blockage ratio effect, which means the ratio between the turbine and channel areas, owing to assessing the numerical results with an analytical solution proposed by Guy Tinmouth Houlsby (Appendix 1). Afterwards, each prototype piece was successfully designed in and printed through a 3D printer in Polylactic Acid (PLA), to be experimentally tested inside a recirculating water channel, located at the Polytechnic Engineering School of Mieres (the University of Oviedo) in a low-velocity scenario (v inlet < 1 m/s). By changing the height of the gate downstream of the flume, the designed prototype has been tested under three increasing values of flow rate [m3/s], by assessing five velocity points for each considered flow rate. Therefore, in this work, the methodology adopted to extract the experimental characteristics curves based on measured and indirectly computed parameters, such as P Mechanical Power [W], ω Angular velocity [rpm], Power Coefficient and TSR λ respectively, which maximize the theoretical turbine efficiency, are defined, and discussed. Moreover, it has been proved that the Blockage effect determines an increment of the maximum measured Power Coefficient with a consequent reduction in the water depth and growth in flow velocity inlet. Nevertheless, Blockage is not the unique effect that strongly affects turbine performance. Still, there is a strict correlation with the flow approximation to a supercritical flow condition. So, the turbine’s behavior is also linked to the Froude Number variation that has also been evaluated and considered in the results analysis. With this end, the experimental data was firstly used as an input parameter to solve a computational sequence proposed by Houlsby for an Actuator Disk in an open channel flow, which calculation is attached in (Appendix 2). With the aim of comparing the experimental and analytical axial induction factor a, maximizing the power extraction. Secondly, a multi-phase three-dimensional CFD simulation has been calibrated with the same experimental data to compare, on the other hand, the characteristic curves experimentally and numerically obtained in specific hydraulic fluid conditions. Thirdly, it has been applied another validation strategy of the CFD model, by investigating on the free-surface variation measured and numerically computed, in specific sections located upstream and downstream of the turbine. Therefore, the Volume of Fluid (VOF) model implemented gives information and capture the water-air interface resulting in a useful integrative tool to study other kind of prototypes, although the experimental assessment undoubtedly remains an essential part of this kind of studies. In conclusion, to investigate how the experimental experience could also be extended to a different case, by defining the scale parameters, useful to characterize a larger turbine prototype, the Reynolds and the Froude analogy have been introduced.
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