Author(s): M. Musa; M. Heisel; M. Guala; C. Hill

Linked Author(s):

Keywords: Hydrokinetic turbines; Geomorphic impacts; River morphodynamics; Scour; Turbulence modeling

Abstract: The present research investigates aspects of the local and non-local geomorphic impacts that fluvial in-stream hydrokinetic turbines introduce in the river morphodynamics. Marine and Hydrokinetic (MHK) energy is an emerging sustainable technology which produces clean energy harnessing the kinetic of waves and naturally occurring water flows such as tides, rivers and ocean currents. In particular, rivers are an overlooked potential source of local and continuous kinetic energy that can power remote regions in the World. A crucial issue that needs further attention is the interaction between these devices and the physical fluvial environment such as the bathymetry, sediment transport, and the morphodynamic processes. Recent experimental investigations demonstrated that in-stream hydrokinetic turbines actively interact with river bathymetry and sediment transport. Specifically, [1] showed that an operating turbine generates a remarkable localized erosion-deposition pattern significantly larger than the one created by in-river constructions, such as bridge piers. This signature persisted when migrating bedforms (live-bed condition) are present, yet it remains localized around the turbine(s), leaving the channel morphodynamic unaltered in the far field [2]. The proposed research here aims to extend preliminary findings on both local and non-local morphodynamic effects of MHK turbines in fluvial environments. First, a theoretical model framework based on the phenomenological theory of turbulence was developed and validated using the limited experimental data available to predict the scour at the base of the device [3]. This is of extreme importance during foundation design, installation, operation, and maintenance (IO&M), and long-term structural integrity. Then, potential non-local morphodynamic impacts were explored at Saint Anthony Fall Lab (SAFL) through an ad-hoc asymmetric installation of two turbine models within the channel cross section. Asymmetric flow disturbances are in fact known to introduce non-local geomorphic effects like forced bars [4, 5, 6, among many others]. Finally, a 12-turbine staggered array model was deployed in a wide channel to extend the previous findings on geomorphic effects and at the same time to characterize the flow deficit and qualitative energy output within the plant.

DOI: https://doi.org/10.3850/978-981-11-2731-1_071-cd

Year: 2018