Numerical Analysis Of Ship Stern Flow On Rubble Bed

Rubble Bed was damaged by the erosion of propeller jet, which threatened the pieruse of safety. It was a new problem in the field of pier detection and evaluation inrecent years, while domestic ports, coastal design specifications did not consider therole of ship wake of the rubble bed erosion.This paper, making use of the CFD software FLUENT powerful computingcapabilities, taking the ship into (off) Port process, draft and starting power threefactors into account, simulates a propeller jet field in the process of the quay wall andthe base of the bed surface, and comes to the law of development of the jet field;based on the propeller jet theory, it summarizes the empirical formula of the base bedsurface and shoulder position scouring velocity under different conditions; eventually,it explains the mechanism of propeller jet scour and the rubble bed in theory.The paper mainly studies the following aspects:1. Analyze the results achieved by the domestic and foreign scholars in thepropeller jet theory study, and master the basic form of the empirical formula of thepropeller jet velocity.2. Based on the three-dimensional model of propeller, make use of computationalfluid dynamics software FLUENT to establish the three-dimensional numerical modelof the rubble bed in the seabed conditions.3. In the condition of mixed base, it mainly studies the specific impact of the twoboundary conditions between the main quay walls and the base under the bed, andsimulates numerically for specific conditions among the ship into (off) Port process,draft depth and starting power separately and in combination with each other, andcomes to the law of development of the jet propeller jet between the quay wall and thebase under the bed, and summarizes the empirical formula of the flow rate and itsposition of maximum scour the surface of the foundation bed.4. rubble bed numerical model is established according to the actual engineering.According to the distance between the propeller and the seabed, the propeller jetaffected zone are divided again. The process of numerical simulation is still toconsider three factors, that is the ships into (off) Port process, draft depth and startingpower. Based on the results of the numerical simulation, it comes to the law ofdevelopment of the propeller jet in the impact of the quay wall and the rubble bed,summarizes the empirical formula of base bed shoulder position of maximum erosion flow rate, the surface of the foundation bed scour flow rate and its position.5. Depending on forms of rubble bed, the scour mechanism of propeller jet onrubble bed mainly divided into two categories: direct scouring and backwashing.Direct scouring generally located in the shoulder of rubble bed. But backwashingwere encountered in varieties of base bed forms. Generally, factors mainly include herelative height of the propeller position, speed, and propeller base bed surface.