Optimization of Bow Bulb Configurations on the Basis of Model Wave Profile Measurements

Abstract

The present approach to bulb design may be regarded as a synthesis of the experimental with the theoretical method. The basic wave patterns of the main hull and the bow bulb are obtained from measurements in the model tank. The theory is then applied for predicting the effect of changes in bulb size and location on the wave pattern and for calculating the wavemaking resistance from the wave pattern. This combination allows the extraction of maximum useful information from a minimum number of experiments. The original conception of this method should probably be attributed to Inui but the technique actually used here is the one devised by Sharma. &&A crucial hypothesis in this method is the approximate theoretical principle of simple linear superposition of the free-wave spectra of the main hull and bow bulb to yield the total free-wave spectrum of the composite bulbous bow hull form. A practical problem lies also in deciding just how a bulb shape should be altered so as to effect any desired changes in the amplitudes and phases of the bulb wave spectrum. The purpose of the present study was to verify by a few simple experiments the actual validity of this method as a practical design tool.