Development of a proof-of-concept lift-type pico-scale vertical axis wind turbine for low wind conditions

Resumen

The development of Pico-scale Vertical Axis Wind turbines (P-VAWTs) takes relevance because small scale energy generation projects thought around sustainable and easy-to-replicate solutions could bring electricity to isolated communities who lack the service, not uncommon in Colombia, allowing them to have a better quality of living. The VAWTs present advantages like working well in turbulent unpredictable conditions capturing wind from any direction, making them suitable for small scale applications. The appeal for P-VAWTs lies in the possibility of harnessing wind energy in places where space is limited or where getting the infrastructure is a challenge. Lift-type turbines are more efficient overall and present a broader operating window, which is desired, but at the cost of a poor self-starting capability hindering their small-scale potential. Knowing the turbine would work beforehand under the conditions on site could reduce costs and increase the adoption of the technology.

The main objective of the project is to propose a methodology for developing a lift-type pico-scale VAWT for low wind conditions. Three specific objectives are set: first, define the design criteria and operating conditions for a P-VAWT used as a case study; second, establish a design process for a proof-of-concept turbine thought around meeting the imposed requirements; and third, evaluate the feasibility of an obtained pre-dimensioning for the VAWT via experimental testing, contrasted against an analytical method. This work focuses on showing the methodology for the development of the proposed P-VAWT and the advancements made in the project so far.

The development method starts by limiting the working conditions, involving the expected performance based on an analytical model, coded and verified against literature review, to get the theoretical characteristic curves for the design parameters. An experimental setup is proposed to further verify analytical results against real-world testing. Once the size of the turbine is known, predicting the theoretical power output is possible, as a function of the wind speed and geometrical parameters dimensioned at this stage. With the parametrization in place, the turbine can be designed to meet the criteria and then manufactured by 3D printing as an introductory approach. When testing the prototype, a constant freestream velocity must be guaranteed to the turbine, the velocity profile in front of the model is recorded and a dynamometer is used at the shaft to measure the power output; torque and rotational speed are captured as well. Tests are repeated for different wind speeds and the results are processed obtaining the non-dimensional characteristic curves of the model turbine.