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In order to compute the performance of a propeller blade using blade element momentum (BEM) method, the two- dimensional airfoil performance of the propeller blade in terms of lift and drag coefficients is necessary. Such data usually can be obtained from model experiment only for limited range of angle of attack (AoA). Therefore, it is necessary to extrapolate the limited experimental data to obtain the data for the whole range of AoA. The present study uses 2 (two) methods which are Viterna and Montgomerie methods in order to extrapolate the performance of an airfoil. The formulas and procedures of both methods are presented and their application are also demonstrated using an airfoil shape of NACA23012. From this study, a relatively good agreement of the airfoil performance in terms of lift and drag coefficients can be found from computation results of the both methods.

Energy Procedia Vol. 65 tahun 2015 In order to optimally explore the Indonesian ocean wind energy using a mobile floating structure (MFS), the present carries out an investigation on ocean wind energy potential around Sulawesi and Maluku islands. The wind data used for analysis are from year 2008 collected by QuikScat satellite which used scatterometer to measure the wind speed above sea surface. Weibull distribution with two parameters is used to represent the characteristics of the wind model. Several methods are used to compute the parameters which are regression analysis (LRM), maximum likelihood method (MLM) and moment method (MM). The obtained parameters are used to compute the energy density of the sea areas around the islands. From this study, the sea areas which have the highest energy density every month could be determined. The areas are to be considered as the location of the MFS.