Design of a hydrokinetic turbine

Abstract

Hydrokinetic turbine power production depends on the interaction between the rotor and water. Therefore, an optimum geometry of the rotor must be designed and constructed to capture the maximum water energy and convert it into a usable energy. The steps involved in the design and numerical simulation of a small horizontal axis hydrokinetic turbine rotor are presented based on the same incompressible flow techniques used for designing wind turbines. Three blades of a 1 Hp (746 W) prototype hydrokinetic turbine were designed for a water velocity of 1.5 m/s with a tip speed ratio of 6.325, an angle of attack of 5• and 0 • as the pitch angle; in order to obtain the maximum power coefficient of the turbine. This coefficient was 0.4382, near the Betz limit. S822 airfoil was used to generate the coordinates of the blade. CFD simulation was carried out using Ansys CFX to estimate the performance of the blade design. Furthermore, FEM was successfully used for stress calculations on turbine blades under the influence of centrifugal and hydrodynamic loading.The designed hydrokinetic turbine can be used for pico hydro generation in rural communities non-connected to electricity services through the national interconnected electric system, due to its simple structure, and low cost of initial investment. Additionally, it can be locally manufactured, the environmental impact is negligible, since large dams are not involved, and the schemes can be managed and maintained by the consumer.

Design and numerical analysis of an efficient H-Darrieus vertical-axis hydrokinetic turbine

“…In general, two fundamental issues must be considered simultaneously in rotor design process: hydrodynamic performance and structural design. The hydrodynamic characteristics of the turbine are influenced by the selected hydrofoil [6,7,31,32].…”

“…Thus, Equation (1) gives the ideal power in a fluid flow. However, hydrokinetic turbines are limited by blade efficiencies, mechanical losses in transmissions, electrical losses and by the theoretical amount of energy allowed to be extracted from water [31][32]. Because of these losses and inefficiencies, two more variables are added to Equation (1).…”

“…These Cp values vary with the turbine size and depend on the water speed, rotational speed of the turbine and blade parameters such as θ and α [6,[34][35][36]. The pitch angle for a horizontal-axis hydrokinetic turbine is the angle between the blade motion and the chord line of the blade [31,32]; whereas for a vertical-axis hydrokinetic turbine θ is between the line perpendicular to the blades motions and the chord line of the blade. In turn, α is the angle between the relative water velocity and the centreline of the blade.…”

“…On the other hand, λ is the ratio of the speed of the blade, at its tip, to the speed of the flowing water. This ratio has a strong influence on the efficiency of the turbine [31,32,35]. TSR of a hydrokinetic turbine is defined as Equation.…”

Influence of the diffusor angle and a damper opening angle on the performance of a hydrokinetic turbine

“…A water velocity ( V 1 ) of 1.5 m s −1 with a tip speed ratio ( ) of 6.325, an angle of attack ( ) of 5 degrees, 0 degrees as the pitch angle ( ), power coefficient ( C p ) of 0.4382, drive train efficiency ( ) of 70%, rotational speed ( ) of 13.952 rad s −1 and a S822 airfoil profile were used for the design of the rotor blade. The radius ( R ) of each blade was 0.68 m .…”