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In this study, the computational and experimental examination of the hydraulic cross-flow turbine (CFT) is presented. The experimental studies are conducted at the turbine laboratory of Gebze Technical University. The commercial Computational Fluid Dynamics (CFD) software, Star CCM+, is employed to calculate three-dimensional, incompressible, steady Reynolds-Averaged Navier–Stokes (RANS) equations for the flow inside the CFT. In the numerical model, the rotational motion of the blades is modeled by means of the moving reference frame approach. The correlation between the turbulent viscosity and the velocities is acquired using the standard k-ɛ turbulence model. The computational results are obtained in terms of the torque, power, and efficiency of the turbine. The outcome of this research reveals that the CFD software used in this study can reliably be used to predict experiments since the numerical model can accurately estimate the experimental values of the torque, power, and efficiency of the CFT. [ABSTRACT FROM AUTHOR]

Abstract  The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air–water flows, is described in this paper. The air–water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air–water flows. [ABSTRACT FROM AUTHOR]

The characteristics of the fluid–structure interaction on the flexible blades of a horizontal-axis water turbine are studied; this bioinspired technology features mechanical simplicity, performance and lifetime improvement, and low fish impact risk, all characteristics of a truly sustainable renewable energy exploitation. A surface-tracking method synchronized with force measurements was applied on a surrogate model of single-bladed, vertical-axis water turbine in a water channel. This allows for the characterization of the structural deformations and their link to the hydrodynamic forces, over a large range of turbine designs and operating points. It is shown that the phase angles of the maxima in blade deformation coincide with those of the load maxima on a rigid blade in identical flow conditions. The influence of the turbine's tip/speed ratio on the blade deformation and blade load is investigated. With the chosen blade design, hydrofoil deformation is found to be maximum in the operating points where the performance improvement is maximized ( k o = 0.3 ). With lower values of reduced frequency (corresponding to lower rotation speed), fluid-induced forces dominate the fluid–structure interaction. Conversely, at higher frequencies, structural inertia dominates the interaction, and blade deformation is again reduced. Results suggest that the optimal blade rigidity may depend on the operating point; nevertheless the potential of the flexible-blade design is demonstrated through clear linking of fluid-induced forces and blade deformation in the complex flow conditions of the Darrieus water turbine. [ABSTRACT FROM AUTHOR]