Vertical Axis Wind Turbine Project

Cody BeckemeyerAdvisors: Junkun Ma

Cris Koutsougeras ET 494

Fall 2013

Comparison to Horizontal Axis Wind Turbine

Vertical Axis Wind Turbines can be placed independently of wind direction, perfect for places that the wind changes daily

Gearbox and generator are able to be placed near the ground, so they are easier to be maintained than HAWT

VAWT have lower rotational speed and lower tip speed ratio therefore higher torque is involved

HAWT have higher tip speed ratio and coefficient of performance Cp, but have lower torque

VAWT have either low or insignificant starting torque so the rotor must be brought up to speed by either a small generator as a motor or a small secondary rotor

Three Blade Turbine With Pivoting Airfoils

NACA0012 Airfoil

Angle of Attack Θ- It is the angle between the chord line of the

blade and the relative wind or the direction of the air flow

- changes due to the variation of the relative velocity

- Rotating the blade will alter the angle of attack.

Driving ForcePressure on the surface of the airfoil creates

the force that drives the rotation of the system.

Comsol MultiphysicsComsol was used to get the initial pressures

over the surface of the airfoil.2D modeling of the airfoil in a simulated wind

tunnel at 5 m/s and standard atmospheric pressure.

Rotating the airfoil through 360 degrees allowed me to find the pressure at any given angle of attack.

Comsol Multiphysics

Distributed PressurePressure is distributed over each individual segment.Using this, Net Pressure can be calculated.

Equal pressure distribution minimum pressure

Calculating Concentrated PressureEach segment has a distributed pressure, but

the concentrated pressure is the key to calculating net Pressure.

X and Y magnitudesNet pressure is found using the obtained x

and y magnitudes of pressure with Pythagorean Theorem.

Pressure with attack angle at 30˚

Torque Is The Key To MotionCalculating the torque generated on the

support arm at any given angle allows us to adjust the angle of attack so that maximum efficiency is achieved.

Support arm in motionAs the support arm begins to move from its original position, an angle alpha Will be created. This angle is used to calculate torque as the length of the Support arm “changes”

Lift and Drag- As both the magnitude and orientation

change the resultant force Fr changes- The resultant force is composed of both

normal component Fn and tangential component Ft

Calculations Gathered131 X coordinates and 131 Y coordinates compose the

surface of the foil. Using the difference between each and its

corresponding coordinate, I found the length of each segment and used this in conjunction with the distributed pressure for a concentrated pressure.

The concentrated pressure is calculated into the X and Y magnitudes that compose it.

Summation of these components led to finding the net pressure via magnitude formulae(Pythagorean theorem).

Once the net pressures are obtained, using the length of the supporting arm, torque can be calculated by T=Fd

Torque Generated

VAWT Project – Cody Beckemeyer