Research On Ship-Engine-Propeller Matching Under Off-design Conditions

With the rapid development of design,manufacture and control information technology in the field of ships,the world-famous propeller manufacturer LIPS was acquired by the Finnish Wkalrtsilkal diesel engine manufacturer,and the world's major diesel engine manufacturer MAN B&W owns the propeller design and production departments,which indicates that the integration of ship propulsion system has gradually become an inevitable trend of ship design.As the core of ship propulsion system integration,ship-engine-propeller matching plays an important role in improving the economy and safety of ship operation.However,the ship-engine-propeller matching is generally based on the ship design operating point.So,the main engine and propeller parameters are designed to operate optimally under the design operating conditions,while the ship often operates under the non-design operating condition,the performance of ship-engine-propeller matching and the main engine optimal operation performance are difficult to obtain.Therefore,this paper carries out the research on matching design of "ship-engine-propeller matching" under design conditions,and also studies the matching characteristics of main engine and propeller under off-design conditions to ensure that the ship can meet the design and operation requirements under off-design conditions.Based on the environment of MATLAB/GUI,this paper establishes an integrated platform for propulsion system design.The platform includes ship resistance calculation module,ship-main engine matching module(preliminary matching),main engine-propeller matching module(final matching)and propeller checking module.There are three factors affecting the selection of low-speed engine design operating point in ship-engine matching module,and the engine-propeller matching module includes two matching methods: traditional regression fitting method and genetic algorithm method.The genetic algorithm is used as the optimization method of ship engine and propeller matching,and it is compared with the traditional method.In order to study the performance of ship-engine-propeller matching under variable working conditions,this paper establishes a simulation model of propulsion system under variable working conditions based on MATLAB/Simulink environment,and carries out simulation analysis of the propeller matched by the platform using traditional regression fitting method,genetic algorithm method and the propeller used by actual ship under variable working conditions respectively.According to the data of 38800 DWT bulk carrier,this paper uses the matching platform to calculate.The accuracy of the platformis verified by the calculation results.At the same time,it shows that the matching method based on genetic algorithm can find more efficient propellers and simpler calculation process than the traditional regression fitting method.Based on the simulation model of variable working condition propulsion system,the simulation is carried out under three working conditions: design condition,light load condition and heavy load condition.The simulation results show that the design propeller adopted by the real ship under variable working conditions are the best,followed by the propeller matched by genetic algorithm matching,and finally the propeller matched by the traditional matching.At the same time,the propeller matched by the traditional method can not operate under the non-design condition.This result shows that ship-engine-propeller matching only according to the design conditions is one-sided,which will lead to problems in the matching of propellers under non-design conditions.Therefore,it is of great significance to consider the combination of design operating point and off-design condition for ship-engine-propeller matching.