Aerodynamics Analysis Of Helicopter Rotor Blade Using Free-Wake Method

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Date
2006-05
Authors
Mustapha @ Mustafa, Ghazirah
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Abstract
The flight capability of the helicopters in hovering and no require a run way for their take off and landing had made helicopters offer various applications. Such ability was available if the helicopter was designed to have a technical system to overcome to those problems demanded by the flight requirements. Among all components that make helicopter operates successfully in the air, clearly the rotor blade play the most important role. As result the capability in the aerodynamics performance analysis is important in the helicopter design stages. The most representative of the governing equation for the flow past through a rotor blade helicopter is the Navier-Stokes equation for the rotor blade aerodynamic analysis. Unfortunately to solve this equation demanded a high performance computing facility and very fine a computational grid system. As result an alternative method with less computing !equirements need to be developed. The present work introduces the use of free wake method for the aerodynamics performance of the rotor blade helicopter. Here the presence of wake vortex sheet which shed from the blade would be obtained is part of the solution. The blade was represented by a single bound vortex with varying strength of circulation due to the variation of the effective angle of attack along its span. The rotational movement of tre rotor blade considered as discrete motion. The development of wake vortex sheet starts with no sheet. As the blade move from one blade azimuth position to n.ext position, the sheet was released to the flow according to the local flow velocity. This velocity represents the summation of the vector velocities due to the free stream incoming velocity, the bound vortex attached on the blade and the vortex which already present in the flow field. The effective velocity along the blade span was determined in similar way but with additional velocity due to a rotational blade motion. xiv The free wake method as an approximation method required some numerical parameters to be defined as input to perform the computational process_ The assessment on the required numerical parameters found that the free wake method can be used as a tool for the aerodynamics analysis of the rotor blade_ The Free Wake method as well as the other method which derived from The Blade Element Theory required an accurate data both in the term of rotor blade configurations as well as the aerodynamics characteristics of the blade sections_ The availability such data was required if the Free Wake method would be compared to the experimental result, this represents the suggested work for the future research_
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Keywords
Free wake method for the aerodynamics performance , of the rotor blade helicopter
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