# HTYPE WIND TURBINE PERFORMANCE PREDICTIONS BY A LOW COMPUTATIONAL EFFORT ALGORITHM

## Palavras-chave:

H-type vertical axis wind turbine, VAWT, Low computational effort, Power coefficient## Resumo

The use of vertical axis wind turbines (VAWTs) has been increasing in recent years. H-type

wind turbines may be a good alternative to horizontal axis wind turbines (HAWTs) at places with low

space availability, as occurs in cities, low wind velocity and disturbed wind streams, as occurs in areas

of mountainous reliefs. Hence, methods of wind turbine performance prediction have become even more

important, in wind energy potential studies. They may reduce the number of experimental trials or field

tests needed. However, the wind stream behavior on a vertical axis wind turbine is usually complex and

hard to predict. A low computational effort algorithm for H-type wind turbine performance prediction

was conceived and tested in a regular home computer. At H-type wind turbine simulation, some inputs

are the airfoil, air density and dynamic viscosity, chord length or solidity, rotor height and radius, free

stream velocity, tip speed ratio range for a constant number of blades (also an input), initial guess and

stop criteria of axial induction factor and maximum number of iterations within the stop criteria. For

non-Joukowski airfoils, the lift and drag coefficients are given in input tables, changing with the angle

of attack and azimuthal angle, from π/180 (1o) to 2π rad (360o) and step value of π/180 rad (1o). Each

table refers to a specific Reynolds number. The tables are previously analyzed, and missing or

non-integer angle values of angles of attack with their coefficients are filled-in by linear interpolation.

For Joukowski airfoils, the circle parameters are inputs. The resultant profile and lift coefficients are

analytically calculated. The variation of power coefficient with tip speed ratio curves are similar to the

literature findings. The predicted power coefficient is 2% higher than the maximum value of

experimental results (same tip speed ratio), in a simulation that lasted 34 seconds to run.