Velocity Pattern Analysis of Multiple Savonius Wind Turbines Arrays

Abstract

to gain its optimal power output. Due to the large area involved, an experimental study

can be difficult and non-economical. This paper presents a methodology by which the

location of downstream turbines can be estimated by using velocity pattern analysis.

A wake structure of an isolated helical Savonius turbine with 90º twist angle is first

evaluated by a Sliding mesh method incorporating Reynold Average (RANS) turbulence

model Spalart Allmaras. The formation of vortices outside the wake is then observed.

It was found that by placing a downstream turbine at the location of the strongest

vortex occurrence, in this case within the area between 20º to 90º with respect to the

advancing blade of the upstream turbine, produces an enhancement of power

coefficient to the later. Repeating the same procedure for another downstream

turbine also yields the same result. The last turbine of the line array always experiences

the highest power coefficient of all. An application of the concept to a 9 turbine array

in a V formation reveals an overall power improvement of 11%. However, placing the

downstream turbine in other areas of weaker vortex shows insignificant improvement.