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S8 Engenharia Aeroespacial |
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Title:
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DETERMINATION OF THE MASS INJECTION EFFECT IN THE WAKE OF A FIXED AND ROTATING CYLINDER.
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Summary :
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EXPERIMENTAL WORK WAS PERFORMED FOR THE MEASUREMENT OF THE EFFECT OF MASS INJECTION IN A WAKE OF A FIXED AND A ROTATING TWO-DIMENSIONAL CYLINDER. THE JET WAS INJECTED BY MEANS OF A SMALL CYLINDER LOCATED JUST BEHIND THE MAIN CYLINDER. THE JET POSITION COULD BE ADJUSTED IN ORDER TO ASSURE THAT THE BLOWING WAS DIRECTED INTO THE WAKE. A VERY LOW TURBULENCE WIND TUNNEL WAS USED FOR FLOW VISUALIZATION OF BOTH A FIXED AND ROTATING CYLINDER. THE VELOCITY DISTRIBUTION BEHIND DE CYLINDER WAS MEASURED BY A CONSTANT TEMPERATURE HOT WIRE ANEMOMETER IN A GRID OF 100 POINTS AND AT TWO DOWNSTREAM POSITIONS. A SMALL OPEN CIRCUIT WIND TUNNEL WAS USED FOR DRAG MEASUREMENTS USING A SPECIAL TWO COMPONENT BALANCE. RESULTS SHOWED THAT SMALL JET FLOWS COULD REDUCE SIGNIFICANTLY THE WAKE OF BOTH FIXED AND ROTATING CYLINDERS WITH THE INHERENT REDUCTION OF THE BASE DRAG. THE JET AND WAKE MIXING MEASURED IN DETAIL WITH A FINE GRID AT THE DOWNSTREAM POSITIONS SHOWED THAT THE JET MIXING LAYER RAPIDLY SMOOTHES OUT THE VELOCITY GRADIENT BETWEEN JET AND WAKE. AS THE JET WAS BLOWING OUTSIDE THE MAIN CYLINDER THIS INDICATE THAT THIS SYSTEM COULD BE USED TO CONTROL THE VORTEX SHEDDING OF STRUCTURES SUCH AS BRIDGES, CHIMNEY AND TOWERS.
KEYWORDS: BLUFF BODIES; MAGNUS EFFECT; DRAG REDUCTION; MASS INJECTION.
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Author :
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Catalano, Fernando Martini
Croce, José Antonio Garcia
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Paper View :
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