Basic equations for estimating the aerodynamic power captured by the Anderson vertical-axis wind turbine (AVAWT) are derived from a solution of Navier–Stokes (N–S) equations for a baroclinic inviscid flow. In a nutshell, the pressure difference across the AVAWT is derived from the Bernoulli’s equation—an upshot of the integration of the Euler’s momentum equation, which is the N–S momentum equation for a baroclinic inviscid flow. The resulting expression for the pressure difference across the AVAWT rotor is plotted as a function of the free-stream speed. Experimentally determined airstream speeds at the AVAWT inlet and outlet, coupled with corresponding free-stream speeds, are used in estimating the aerodynamic power captured. The aerodynamic power of the AVAWT is subsequently used in calculating its aerodynamic power coefficient. The actual power coefficient is calculated from the power generated by the AVAWT at various free-stream speeds and plotted as a function of the latter. Experimental results show that at all free-stream speeds and tip-speed ratios, the aerodynamic power coefficient of the AVAWT is higher than its actual power coefficient. Consequently, the power generated by the AVAWT prototype is lower than the aerodynamic power captured, given the same inflow wind conditions. Besides the foregoing, the main purpose of this experiment is to investigate the technical feasibility of the AVAWT. This proof of concept enables the inventor to commercialize the AVAWT.
Analytical and experimental analyses of a variable electromotive-force generator (VEG) show the advantages of this modified generator in hybrid electric vehicle and wind turbine applications with enhancing the fuel efficiency and expanding the operational range, respectively. In this study, electromagnetic analysis of a modified two-pole DC generator with an adjustable overlap between the rotor and the stator is studied using 3-D finite element simulation in ANSYS. The generator stator is modeled with two opposite pole pieces whose arcs span between 15° to 90° in the counterclockwise direction and −15° to −90° in the clockwise direction. A semicircular cylinder whose arc spans between −90° and 90° is used to model the generator rotor. A tetrahedral mesh is used to provide a solution for changes in the electromotive force at different frequencies and overlap ratios. For a constant electromagnetic flux density and fixed number of coils, the changes in the electromotive force at different overlap ratios between the rotor and the stator are obtained in static conditions. There is a very good correlation between the results from simulation and those from analytical and experimental studies.
A modified generator, referred to as the variable electromotive-force generator, is developed to enhance fuel efficiency of hybrid vehicles and expand operational range of wind turbines. Obtaining a numerical model that provides accurate estimates on the generator output power at different overlap ratios and rotor speeds, comparable with those from experimental results, would expand the use of the proposed modified generator in different applications. The general behavior of the generated electromotive forces at different overlaps and rotor speeds is in good agreement with those from experimental and analytical results at steady-state conditions. Employing generator losses due to hysteresis and eddy currents in a three-dimensional model would generate more realistic and comparable results with those from experiment. In this work, electromagnetic analysis of a modified two-pole DC generator with an adjustable overlap between the rotor and the stator at transient conditions is performed using finite element simulation in the ANSYS 3D Low Frequency Electromagnetics package. The model is meshed with tetrahedral or hexahedral elements, and the magnetic field at each element is approximated using a quadratic polynomial. For a fixed number of coils, two cases are studied; one with constant magnetic properties and the other with nonlinear demagnetization curves are studied.
The basic equation for estimating the aerodynamic power captured by an Anderson Vertical Axis Wind Turbine (AVAWT) is a solution of the Navier-Stokes(N-S) equations for a baroclinic, inviscid flow. In a nutshell, the pressure difference across the AVAWT is derived from Bernoulli’s equation; an upshot of the integration of the N-S momentum equation for a baroclinic inviscid flow, Euler’s momentum equation. The resulting expression for the pressure difference across the AVAWT rotor is plotted as a function of freestream speed. Experimentally determined airstream speeds at the AVAWT inlet and outlet, coupled with corresponding freestream speeds are used in estimating the aerodynamic power captured. The aerodynamic power is subsequently used in calculating the aerodynamic power coefficient of the AVAWT. The actual power coefficient is calculated from the power generated by the AVAWT at various free stream speeds and plotted as a function of the latter. Experimental results show that, at all free stream speeds and tip speed ratios, the aerodynamic power coefficient is higher than the actual power coefficient of the AVAWT. Consequently, the power generated by the AVAWT prototype is lower than the aerodynamic power captured, given the same inflow wind condition.
Prior to choosing a site for a wind farm, its wind resources must be known. On-site measurement of wind speed, using an anemometer or any other appropriate measuring device or the use of historical meteorological data for the site (if they exist) enhance the knowledge of the site’s wind resources. Typically, the use of 50-year historical data is recommended by Wind Energy Engineering Standards. For the offshore site in study, only the 24-year historical data from the National Oceanic and Atmospheric Administration (NOAA) data base is available. Wind speed determined from NOAA’s error bars is used to plot Rayleigh probability distribution curves for each month of the year, based on the operational limit of the 5MW NREL reference wind turbine. The site’s average wind speed and gust are determined based on average wind energy capture. A Gumbel probability distribution curve is plotted based on the operational range of the wind turbine in study, using NOAA’s error bars for the 24year historical hourly wind gust for the site. This study uses the estimated mean wind speed and mean gust, to implement BEMT simulations to investigate the aerodynamic forces caused by the wind or gust on the blades of the HAWT rotor. The wind power captured and the power coefficient are estimated for each scenario. Empirical formulae are developed for the estimation of the rotor blade airfoil’s chord length in terms of blade element radius and the axial induction factor for each scenario, in terms of blade element radius.
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