Development of a Hydrokinetic Turbine Backwater Prediction Model for Inland Flow through Validated CFD Models

Abstract

Hydrokinetic turbine deployment in inland water reticulation systems such as irrigation canals has potential for future renewable energy development. Although research and development analysing the hydrodynamic effects of these turbines in tidal applications has been carried out, inland canal system applications with spatial constraints leading to possible blockage and backwater effects resulting from turbine deployment have not been considered. Some attempts have been made to develop backwater models, but these were site-specific and performed under constant operational conditions. Therefore, the aim of this work was to develop a generic and simplified method for calculating the backwater effect of HK turbines in inland systems. An analytical backwater approximation based on assumptions of performance metrics and inflow conditions was tested using validated computational fluid dynamics (CFD) models. For detailed prediction of the turbine effect on the flow field, CFD models based on Reynolds-averaged Navier–Stokes equations with Reynolds stress closure models were employed. Additionally, a multiphase model was validated through experimental results to capture the water surface profile and backwater effect with reasonable accuracy. The developed analytical backwater model showed good correlation with the experimental results. The model’s energy-based approach provides a simplified tool that is easily incorporated into simple backwater approximations, while also allowing the inclusion of retaining structures as additional blockages. The model utilizes only the flow velocity and the thrust coefficient, providing a useful tool for first-order analysis of the backwater from the deployment of inland turbine systems.

Models for a hydropower plant: a review

“…Furthermore, studies about change in guide vane air foil on the flow characteristics of draft tube for improvement of energy recovery, vibrations intensity, stable operation of turbine, design methods of multiphase pumps for hydrodynamic and structural points of view, etc. have been performed widely in the past (Benavides-Morán, Rodríguez-Jaime and Laín, 2022; Niebuhr et al, 2022;Peng et al, 2022).They conclude that the power coefficient is affected by presence of free surface. Similarly, authors in (Lopez Mejia et al, 2021) propose practise guidelines for CFD simulations in turbines studying the performance standard of vertical axis and horizontal axis turbines and those in (Xiong, Deng and Chen, 2021) study about flapping motion in tail edge which is found to present a better stability for turbine.…”

Special Issue on “CFD Modelling and Simulation of Water Turbines”

“…Modelling and simulation of horizontal-and vertical-axis turbines for hydrokinetic applications [10][11][12][13][14].…”

“…All of these contributions use CFD in different problems, ranging from vertical-axis turbines to horizontal-axis turbines, but all have the common characteristic of the inclusion of more details (either geometrical or physical) in the simulation. For example, Niebuhr et al proposed a simplified model for the calculation of a small horizontal-axis turbine that includes backwater effects [10]. The model uses the data generated from CFD simulations that include not only the presence of the walls (channel flow), but also the free surface using a multiphase model.…”