Mathematical Implementation of Effect of Increase in Divergence Angle of a Diffuser on Speed and Power Generation of HAWT using Disk Theory
Publication Date : 22/03/2021
Harnessing wind energy to turn a turbine for power generation requires concentration of the wind at high velocity to give maximum and steady power output. Mathematical relationships are used to analyze the variation of the pressure and velocity of the flow regime in the conical duct. The pressure and velocity magnitude varies oppositely, pressure increases as velocity decreases. This revealed that power extracted by horizontal axis wind turbine (HAWT) is the product of the volume flow rate of air through the turbine and the pressure drop across the blades, which is a result of the thrust of the blades. The mathematical model uses disc theory to predict appropriate position of rotor for maximum power production. The diffuser angles considered are 4 0 8 0 12 0 16 0 and 20 0 . Energy conversion starts at a certain angle say 4 0 and will increasing until a certain angle of about 20 0 and it will begin decline. As the angles are increased the power output of the turbine also increased until when it get to angle 20 0 then it begin to decline. The turbine operation exhibits a reasonable range of tip speed ratio and high eﬃciency. The proposed method suggests that an increase in CP of about 0.035, which is about a 27%, for open angle of 12 0 , 32% for open angle of 16 0 and 38% for open angle 20 0 increase in aerodynamic efficiencies, were attainable with the DAWT concept. This improvement is primarily due to efficient extraction of energy (wind) blowing near the hub of the main rotor, but in part also due to the addition of another energy extracting device called diffuser augmented system.
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