Power correlation for vertical axis wind turbines with varying geometries

Abstract

SUMMARYIn this paper, a new predictive model that can forecast the performance of a vertical axis wind turbine (VAWT) is presented. The new model includes four primary variables (rotor velocity, wind velocity, air density, and turbine power output) as well as five geometrical variables (rotor radius, turbine height, turbine width, stator spacing, and stator angle). These variables are reduced to include the power coefficient (C p ) and tip speed ratio (TSR). A power coefficient correlation for a novel VAWT (called a Zephyr Vertical axis Wind Turbine (ZVWT)) is developed. The turbine is an adaptation of the Savonius design. The new correlation can predict the turbine's performance for altered stator geometry and varying operating conditions. Numerical simulations with a rotating reference frame are used to predict the operating performance for various turbine geometries. The case study includes 16 different geometries for three different wind directions. The resulting 48 data points provide detailed insight into the turbine performance to develop a general correlation. The model was able to predict the power coefficient with changes in TSR, rotor length, stator spacing, and stator angle, to within 4.4% of the numerical prediction. Furthermore, the power coefficient was predicted with changes in rotor length, stator spacing, and stator angle, to within 3.0% of the numerical simulations. This correlation provides a useful new design tool for improving the ZVWT in the specific conditions and operating requirements specific to this type of wind turbine. Also, the new model can be extended to other conditions that include different VAWT designs.

Economic Feasibility of Floating Offshore Wind Farms in the North of Spain

“…Although there are studies about increasing the size of wind turbines, the majority of the wind turbines installed have a rated power of 5-6 MW [21] and they have a horizontal axis [22,23]. Due to the increasing size of the wind turbines and the increasing number of onshore wind farms, onshore locations have become more difficult to find because they are occupied by lots of old onshore wind farms or repowering wind farms [24].…”

Performance investigation of a small Savonius‐Darrius counter‐rotating vertical‐axis wind turbine

“…This is because the Darrius rotors are renowned for their inherent characteristics to work more effectively and retain higher conversion efficiency at higher wind velocities. 15 However, they generally face difficulty to self-start at the low-speed wind, and therefore, external devices are commonly used to resolve such issues. 16 Thus, the two distinctive rotor types are combined in the prototype of the current study in order to take advantage of the inherent characteristics of both designs and to widen the application of the new counter-rotating concept in VAWTs.…”

Conceptual design and numerical simulations of a vertical axis water turbine used for underwater mooring platforms

“…This research focuses on exploring the operating performance and power output of the turbine with a two-dimensional computational fluid dynamics (CFD) method. Sliding mesh model, which uses a time averaged solution to determine the turbine performance, and has been proving to give relatively accurate results for a two-dimensional rotating rotor (Jung et al, 2009;Pope et al, 2011;Akwa et al, 2012;Yang and Lawn, 2011), was used in the simulation. The influence of structural parameters, including foil section profile, foil chord length and blocking ratio, on the turbine performance are investigated over a range of tip-speed-ratios (TSRs).…”