Study On Resistance Optimization Of The Vessel Form Of Bulbous Bow Based On FLUENT

Ship resistance prediction is a key indicator reflecting the rapidity and safety of ships.Its essence can be described as a complex measuring method for the flow of viscous fluids around the exterior of a hull.The flow state of the viscous flow field is not stable,and the difficulty of forecasting is obviously increased without the pool model.The simulated environment does not meet the conditions of the real sea state,resulting in a large deviation of the calculation results.In order to solve the problem of insufficient accuracy and long computing time in resistance prediction,it is necessary to propose a rapid forecasting method for optimizing the hull profile.The article conducts in-depth research on this aspect.This article systematically reviews the ship resistance theory and method,and details the development history and research status of CFDs at home and abroad.The respective characteristics of Froude's resistance exchange algorithm and three-dimensional resistance exchange algorithm are compared and effectively combined with CFD technology.The numerically-dragging tank model is established for the trawler to realize the meshing of the intricate hull type,providing a good pre-processing environment for FLUENT numerical simulation.In order to optimize the bulbous bow shape of the ball nose structure used in real ships,a parametric design method based on elliptic arcs and polynomial expressions is proposed,and collision angle bulbous bow and S-V bulbous bow are designed.FLUENT calculates the type and geometric parameters of the bulbous bows that have the best drag reduction effect,improves the flow field with the shape of the tail,and formulates a complete optimization plan for drag reduction of the bulbous bow shape.Considering that the trawler operation has a low speed and the viscous drag occupies a significant proportion of the total resistance,the magnitude of the wave-resistance is largely determined by the bulbous bow.Therefore,the process of optimizing the shape of the bulbous bow does not exclude the impact of wave resistance.The result of FLUENT direct output is only viscous resistance,and it cannot accurately predict the resistance of a real ship.This paper captures the wave-making resistance under low-velocity state of the fishing vessel,applies the wave resistance subsidy to the calculation results based on the Dawson slow ship theory,and corrects the missing of the resistance component of the wave in the total ship resistance calculation process.FLUENT adopts the ship-wide simulation to greatly improve the calculation accuracy,but the tail flow field will cause some interference to the resistance calculation.Selecting the appropriate tail shape can achieve the effect of reducing the resistance together with the shape of the bulbous bow.In this paper,based on the ship CFD proposed bulbous bow shape optimization method for stern trawler,with fast,accurate characteristics of the forecast,the numerical pool model and the bulbous bow parameterized model have practical application value,can be used as a reference parametric model for similar types of research.The method of optimization of bulbous bow reduction for fishing vessels provides ship designers with a scientific and complete preset scheme,which is of great significance to the design and development of new type fishing vessels.