波浪伴流中における平板の抵抗試験

概要

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A flat plate of 2.5 m long was towed on the middle line fo two wall-sided ships of the same length placed symmetrically with respect to the flat plate, the distance between the outside walls of the ships being 0.6 m and 0.7 m. The draft of the plate was about 0.30 m and that of ships 0.362 m.The total resistance of the plate was obtained by a magneto-strain type dynamometer and the wave profiles on the surface of the plate, as well as the velocity distribution, were also recorded.After recognizing the fact that the wetted surface area and the mean velocity on the plate were nearly equal to the values in open water test, or the test with the plate alone, the air resistance, the proper resistance of trip wire and the correction for laminar area were subtracted from the total resistance and finally the pressure resistance due to the difference of the wave height at the fore and after edges was estimated and subtracted.The frictional resistance of the flat plate thus obtained were compared with that in open water.The author had given formerly a method for calculation of form effect K, which was applied in this case assuming the two dimensional potential flow.The difference of the resistances in open and wake flow was fairly well in accord with the calculated value of form effect, the discrepancies in some regions of velocity being mostly due to the undue estimation of pressure resistance.
社団法人日本船舶海洋工学会の論文