Improvement of sinusoidal pitch for vertical-axis hydrokinetic turbines and influence of rotational inertia

Computational Fluid Dynamic Simulation of Vertical Axis Hydrokinetic Turbines

“…Nevertheless, the use of numerical methods associated with different algorithms of CFD to analyze complex fluid flow applications has grown in recent years due to the rapid development of computer technology. Therefore, the analysis of vertical axis hydrokinetic turbines is also being conducted using CFD simulation [18][19][20][21][22][23].…”

“…The CFD tools transform the governing equations of the fundamental physical principles of the fluid flow in discretized algebraic forms, which are solved to find the flow field values in time and space. The simulation results can be very sensitive to the wide range of computational parameters that must be set by the user; for a typical simulation, the user needs to select the variables of interest, turbulence models, computational domain, computational mesh, boundary conditions, methods of discretization, and the convergence criteria, among other simulation setup parameters [20][21][22][23]. In general, the CFD tools compute the flow field values by the equations of the fundamental physical principles of a fluid flow.…”

“…The hydrodynamics and performance of these turbines are governed by several parameters such as (i) the tip-speed ratio (TSR or λ ¼ Rψ=V, which is defined as the ratio between the blade tip speed and the fluid speed (V), being R the turbine radius and ψ the rpm); (ii) the aspect ratio AR ðÞ , defined as the ratio between the hydrokinetic turbine height H ðÞ and its diameter D ðÞ ; and (iii) the solidity σ ¼ Bc=2R ðÞ , which refers to the ratio of the product of the blade chord length c ðÞand the number of blades B ðÞ , the blade profiles, and the chord Reynolds number Re ¼ ρVc=μ ðÞ , where ρ and μ are the water density and viscosity, respectively. In the literature, there are several studies including experimental, numerical (computational fluid dynamics) and theoretical studies, focused on optimizing the hydrokinetic turbine geometric parameters, mainly the blade profiles, using different techniques [8,[16][17][18][19][20][21][22][23]. Figure 1 shows the typical power curves for the most common types of turbine.…”

A review on technology, configurations, and performance of cross‐flow hydrokinetic turbines

“…The only difference is in the density of the fluids, ie, water and air. Water is about 820 times denser than the air that is why the energy produced by the water may be equal to the energy produced by the wind even at the low flow velocities . Figure represents the behavior of hydrokinetic and wind turbine power densities at different flow velocities.…”

“…Water is about 820 times denser than the air that is why the energy produced by the water may be equal to the energy produced by the wind even at the low flow velocities. 11,12 Figure 1 represents the behavior of hydrokinetic and wind turbine power densities at different flow velocities. The conversion of hydrokinetic energy in the form of electrical energy through a turbine operates at almost zero head 14 and the turbines used for this conversion are known as ultra-low or zero head hydro turbines or free flow turbines.…”