FLOW SEPARATION CONTROL ON WIND TURBINE BLADES USING AN ARRAY OF FLUIDIC OSCILLATORS

Abstract

Wind turbines produce energy by using the kinetic energy of the wind. It is one ofthe renewable sources of energy and has gained momentum in the present energy hungryworld. Increasing efficiency of wind turbines and stalling of turbine blades beyond themaximum cut off speed is critical for any wind turbine operation. Different types of flowseparation control devices have been studied over the recent years for controlling flowseparation, as well as for the purpose of stalling the turbine blade.Fluidic oscillators has been identified as one of the active flow control technologiesand research has been going on to equip them in wind turbines. These devices producesoscillations by making use of Coanda effect. The no-moving part mechanism of producingoscillating output flow from the fluidic oscillators makes them ideal for long runoperations and without maintenance requirements.The current report contains tests performed on an array of fluidic oscillators underdifferent conditions. A normal fluidic oscillator operates with the help of feedback loopattached to its control ports. A mechanism of switching by using resonance rather thanfeedback loop, was introduced to produce high frequency exit flows. Tests have beencarried out using feedback loops and resonance on the fluidic oscillator array and the resultswere presented. A number of drawbacks for the fluidic oscillator array in producingproper oscillations were identified and discussed.From the experiments, it was suggested that, the use of two exit output fluidic oscillatorswhich were stable, were more appropriate for use. These oscillators, in the formof an array will be able to control flow separation over a large span and can be used forfuture research.Flow separation control test using oil flow visualisation has been performed on onemodel placed in wind tunnel and a base line flow separation test was also performed onanother model having historic data of wind tunnel tests. The second wind tunnel modelwas setup for future flow separation control tests, after obtaining proper oscillation asrequired from an array of oscillator.Details of attempts to design and test two-exit port fluidic oscillator, based on existingdesign and literature have been provided.

Date of Award	1 Aug 2012
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Shan Zhong (Supervisor)