Experimental investigation of the effects of tip injection on the characteristics of the tip vortex on a model wind turbine

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2015
Anık, Ezgi
This study presents the results of an experimental study performed on a horizontal axis wind turbine to investigate the effects of spanwise steady tip injection on the tip flow characteristics of a model turbine. Experiments are performed in front of an open-jet wind tunnel facility on a specially designed model wind turbine that has a 3-bladed rotor with NREL S826 airfoil profile. The turbine has a specially designed injection system which consists of a pressure chamber, a hollow shaft, pressurized hub and blades with injection channels for tip injection. The model turbine is also instrumented with a torquemeter, a 6-axes Force-Moment transducer for load measurements, an electrical motor to control the rotational speed, a nacelle, a tower and a base. Time Resolved Particle Image Velocimetry (Tr-PIV) measurements are performed at 5 m/s constant wind speed, at TSR=5 for baseline and two selected injection ratios. Tr-PIV results showed that, injection changes the tip vortex as well as wake characteristics of the model turbine. Injection affects the size, location, vorticity and the trajectory of the tip vortex also; it causes an expansion in the wake and increases the velocity behind the turbine depending on injection ratio. In vi addition, a power budget analysis is performed to see how feasible to use tip injection in sense of an active flow control method. To understand the relation between performance changes and tip flow field characteristics a 1D mass flow analysis is done. Results show that although tip injection has an increasing effect on performance characteristics of this model turbine it is mostly inefficient to use injection according to the power budget analysis. According to the mass flow analysis, tip injection increases the effective span therefore the mass flow rate which results in increase in performance characteristics dependent on injection ratio.

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Citation Formats
E. Anık, “Experimental investigation of the effects of tip injection on the characteristics of the tip vortex on a model wind turbine,” M.S. - Master of Science, Middle East Technical University, 2015.