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Numerical and Experimental Comparison of Performance of Two Stage and Helical Savonius Wind Turbines

  • L. Brito KotheEmail author
  • A. Prisco Petry
Conference paper
  • 491 Downloads
Part of the Green Energy and Technology book series (GREEN)

Abstract

This paper presents a numerical and experimental comparison of vertical axis wind turbine involving two stage and helical Savonius rotors. The experimental study is conducted in the Aerodynamic Tunnel Professor Debi Pada Sadhu at the Fluid Mechanics Laboratory of the UFRGS. The rotors are manufactured by 3D prototyping technique. The numerical simulations are performed using the Finite Volumes Method. The dynamic torque coefficient, power coefficient, and an aerodynamic analysis of the two turbines are compared for tip speed ratios (λ) between 0.2 and 0.8. The torque and power coefficients of the helical turbine are higher than the two stage turbine for most cases. The helical turbine shows less torque variation along each rotation when compared with the two stage turbine. The differences between the numerical and experimental values obtained are between 6.17 and 13.3% for the two stage turbine and between 2.34 and 13.11% for the helical turbine.

Keywords

Vertical axis wind turbines Numerical study Experimental study 

Nomenclature

A

Area, m²

c

Chord, m

CP

Power coefficient

CT

Torque coefficient

dh

Hole diameter, m

db

Bucket diameter, m

e

Thickness, m

epe

Thickness of the buckets, m

F

Force, N

g

Gravity, m/s²

h1

Turbine stage height, m

h2

Thickness of the intermediate plate, m

k

Turbulent kinetic energy, J/kg

mBALANCE

Balance mass, kg

mLOAD

Load mass, kg

P

Power, W

r

Rotor radius, m

rt

Total radius, m

rSHAFT

Shaft radius, m

Re

Reynolds number

s

Overlap, m

tSTRING

String thickness, m

T

Moment, N·m

Vo

Undisturbed air flow velocity, m/s

u

Velocity flow, m/s

uʹ

Velocity fluctuation, m/s

\(\bar{u}\)

Average velocity, m/s

Δt

Time step, s

Δθ

Angular step, °

μ

Air dynamic viscosity, kg/(m·s)

ν

Air kinematic viscosity, m²/s

θ

Angular position, °

ρ

Atmospheric air density, kg/m3

λ

Tip speed ratio of the rotor

ω

Specific turbulence dissipation rate, s−1

ωo

Angular velocity, rad/s

τ

Reynolds stress

Notes

Acknowledgements

The authors would like to acknowledge Capes and CNPq for the financial support of this research.

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Copyright information

© Springer International Publishing AG 2018

Authors and Affiliations

  1. 1.Mechanical Engineering DepartmentFederal University of Rio Grande do SulPorto AlegreBrazil

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