Micro Wind Turbine - Modelling and Testing

Mohammad Uzair Bhati

Abstract

The global energy demand continues to rise as people consume more electricity to power their personal electronics, electric vehicles, and consumer products such as outdoor tools. To generate renewable energy, large scale solar and wind farms continue to receive the most commercial attention. However, portable wind energy turbines have the potential to generate sufficient power for cell phones and other electronic devices. There are two types of wind turbines, horizontal and vertical axis each having their pros and cons. Vertical-axis wind turbines are the main focus of this thesis, with a reduction in their form factor or size and portable applicability. However, a gap exists in the development and deployment of miniaturized VAWT to generate electricity in remote areas. To accomplish this research investigation, a series of tasks were undertaken including the design, modeling, analysis, fabrication and testing of small multi-blade vertical rotors for electricity generation. Eight different airfoil profiles were selected, and two distinct numerical studies were conducted on them. First, the aerodynamic capabilities of these airfoil profiles were virtually analyzed using two software packages, COMSOL and QBlade. Specifically, the airfoil performance was assessed including the lift and drag coefficients at different angles of attack for the incoming wind flow. Second, the airfoils were integrated into rotors and then fabricated using a Fused Deposition Modeling (FDM) 3D printing process. The number of turbine rotor blades was determined using the tip speed ratio. A small-scale wind turbine was available in the laboratory to support limited experimental testing. The wind turbine rotors were attached to various AC/DC electric generators and tested in the wind tunnel with supporting instrumentation. Representative experimental results were collected using National Instruments data acquisition hardware and software. Overall, vertical axis wind turbine rotors with airfoils having a lower camber radius had the highest lift and drag forces, which also translated to higher electricity generation. Also, turbine rotors with airfoil blades that utilized both lift and drag forces optimally generated more electricity as compared to turbine rotors with airfoils that were either lift or drag only. In terms of electric power, a mismatch in the AC/DC electric generator size to the rotors, and mechanical alignment leading to lower efficiency likely contributed to smaller values than anticipated. The numerical and experimental results offer a promising pathway for continued study on miniature VAWT systems.