Research On Flow Field Interactions Of Waterjet-Propeller Hybrid Propulsion System Of High Performance Ship

For the high-performance displacement ships which work in high speed,highpower and multiple conditions,the single type of thruster like propeller or waterjet often can not meet all requirements such as ship's speediness,high propulsion efficiency in all working conditions and low vibration and noise.For this kind of ship,it is worthwhile to do research on how to improve the propulsion performance by using the hybrid propulsion system equipped with waterjet and propeller as the thruster device(referred to as waterjet-propeller hybrid propulsion system).Taking the marine waterjet-propeller hybrid propulsion system as the research object,this paper carries out researches on the theoretical analysis method of propulsion performance of the waterjet-propeller hybrid propelled ship,CFD simulation method of the propulsion performance and flow field characteristics,and flow field interactions of the "shippropeller-waterjet" system.(1)Based on the working principle of propeller and waterjet,and the characteristics of waterjet-propeller hybrid propulsion,this paper established the analysis method of propulsion performance of the hybrid propulsion model-ship and the prediction method of propulsion performance of the real ship.The method to obtain the overall propulsion factor of the ship and the separated propulsion factors of the propeller and waterjet are analysed and sumarized,by the means of the test of hybrid self-propelled ship model,the test of independent propeller-propelled ship model and the test of independent waterjet-propelled ship model.These works can provide theoretical basis for the ship design,model test and performance evaluation of the hybrid propulsion system.(2)Based on RANS method and integrated various numerical methods such as dynamic mesh technique,VOF simulation technology for gas-liquid two-phase flow,simulation technology of thruster body force,this paper carries out research on the CFD numerical forecast methods of the hull resistance,propeller open-water performance,waterjet propulsion performance under free-inflow condition,propeller self-propelled performance,waterjet self-propelled performance,propeller-waterjet hybrid propulsion performance,aiming at both the model ship and the real ship.After mastering the evaluation method of the propulsion performance and the flow field characteristics of the hybrid propulsion system,the performance of the ships with hybrid propulsion system can be evaluated rapidily and effectively,combining with model tests and other helpful means.(3)Based on the above theoretical analysis method and CFD simulation method of flow field characteristics of hybrid propulsion system,the design case of hybrid propulsion system is carried out.Combining with design cases,this paper conduct research on impacts of different spatial layout forms of the waterjet and propeller,such as the horizontal distance,the vertical distance,the up and down distance,and the direction of the propeller rotation.The impacts include the interaction of the flow field of the hull-propeller-waterjetjet propulsion system,and the propulsion performance such propulsion efficiency,and the matching characteristics of the "hull-thruster-host" system.Based on the above work,the flow field characteristics of the hybrid propulsion system can be analysed initially,and the optimized scheme of waterjet-propeller hybrid propulsion system is carried out,which may provide design experience for the stern geometry and thruster design of ships with hybrid propulsion system.Through the research work,the key techniques,including the method of determining the resistance distribution and the seperated propulsion factor of the propeller and the waterjet in the hybrid propulsion system,and the numerical simulation method of the flow field characteristics of the complex hull-waterjet-propeller system,are masterd.This paper designs a preliminary scheme whole system,and then calculate and evaluate the propulsion performance.Through a series of analysis of design cases,the interaction characteristics among the hull-waterjet-propeller is exploried.The above work can provide technical reference for the optimization design and future product development of ships equipped with waterjet-propeller hybrid propulsion system in terms of theoretical basis and evaluation means.