Scale and Roughness Effects of Propeller Section Drag

概要

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In order to investigate the scale and roughness effects on the profile drag of propeller blade which are needed to estimate an open characteristics of ship propeller from those of model propeller, a profile of 3.5 meter in length and thickness ratio 0.04 was tested at both smooth and roughened conditions in the Nagasaki Experimental Tank up to the Reynolds number of 4×10^7,which is very near to that of ship propeller (R_e=(5-7)×10^7 at 0.7R).The following conclusions are obtained : (1) The minimum profile drag of smooth surface in the range of Reynolds number of ship propeller can be expressed by C_D=0.012(t/c)+2(1+2(t/c))C_f(Hughes) (2) The equivalent sand roughness (k_s) of propeller blade may be taken k_s=2k_g (, where k_g is geometrical roughness measured)in completely rough range.These results justify the assumption made by one of the authors in his estimation method of ship propeller open characteristics in model-ship correlation study.
社団法人日本船舶海洋工学会の論文