Behavior of Oil Layer for Twin-hull Oil Skimming Vessels

Abstract

In a previous paper, the authors have shown the supercritical open-channel flow model for the flow of an oil layer around an advancing skimming vessel and have verified that the model is characterized by the densimetric Froude number, using models of mono-hull vessels. Tank tests have been carried out on the flow of an oil layer between hulls of advancing skimming twin-hull vessels by means of the previous paper, using geosim models and different large-sized models with the geosim models. The geosim models with different entrance angles have been tested, at varying ship speeds and oil layer thicknesses. The test results of the geosim models show that the supercritical open-channel flow model and the law of similarity are valid at low densimetric Froude numbers. However, it is very difficult to separate shock wave from the effect of blocking up the oil layer flow between twin hulls. The large-sized models have been investigated for the purpose of improving the test accuracy. It has been verified that the interference between shock wave and negative disturbance lines behind the stem exists. Comparison between theoretical results and experimental ones shows good agreement for the behavior of an oil layer using the large-sized models.