الفهرس 
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Abstract
Fans demand minimum gaps in order to facilitate operation, this gap tip clearance flow is known to have detrimental effects on the axial fans performance. The static pressure difference between the suction and the pressure side of the impeller blades produces a secondary flow over the tip of the rotor-blade.
There is an interest in both the academic and industrial communities to minimize the negative effects of tip gaps. The main aim of the present work is to manage the blade tip casing clearance flow structure in order to minimize the impact of flow structure on the fan performance
Numerical study is carried out to investigate the effect of the addition of winglet to the end of blade on the axial fan performance. Validation and assessment of the used computer program FLUENT 6.2 is carried out by comparing its result with previous researches. Simulation is then carried out to analyze the flow pattern with and without a winglet attached to the fan blade.
Velocity distribution produced numerically showed that the winglet suppresses the secondary flow at the tip gap. Pressure distributions also confirmed the winglet advantages. Calculated performance of the fan used showed general increase of the fan efficiency with 3.5% above those without winglet at the optimum efficiency point and with up to 6 % at off design point.