The Influence Of Power Distribution Analysis And Experiment Study For Hybrid CRP Propulsion

With the Energy Efficiency Design Index(EEDI)of the 3rd and the 4th stages emission reduction targets which is enforced by International Maritime Organization(IMO)coming soon,ship energy-saving emission reduction technology has being paid more and more attention,the contra-rotating propeller(CRP)is increasingly favored as a highly efficient energy-saving propulsion device.There are two forms of CRP,one is the conventional CRP,the forward and aft propeller reverse rotation with the same revolution;the other is the hybrid CRP,the forward and aft propeller reverse rotation with different revolution,which usually is combined with the conventional single propeller and pod propeller.The hybrid CRP has the advantages of high propulsion efficiency and small vibration noise and so on.However,due to the different forward and aft propeller revolution,the design concept,the hydrodynamic performance and the flow field characteristics of the hybrid CRP are different from the conventional CRP.Based on these,this paper has carried out the research method of hybrid propeller design and hydrodynamic performance evaluation,and analysis the influence of the power ratio of the hybrid CRP on the hydrodynamic performance and the flow field characteristics.In this paper,the lifting surface design method and procedure of the conventional CRP are applied to design the hybrid CRP.The principle of selecting the parameters such as the diameter,the number of propeller blade and the disk ratio of forward and aft propeller under different power ratio and revolution ratio are preliminarily determined.The influence of different parameters on the calculated results of hydrodynamic performance are discussed.The hybrid CRP hydrodynamic forecasting method is established.Based on this,to examine the influence of the change of the power ratio and revolution ratio of the forward and aft propeller on the propulsion efficiency,the design of the propeller scheme and the prediction of the hydrodynamic performance were carried out.As the comparative analysis,the single propeller and conventional CRP design and performance evaluation were also carried out.The calculated results show that the efficiency of the conventional CRP is the highest,and the efficiency of the hybrid CRP is between the conventional CRP and the single propeller.The influence of the power ratio on the efficiency of the hybrid is not very significant.In order to verify the calculated results of the CFD method for the hybrid CRP and the effect of the power ratio on the efficiency of the hybrid CRP,two typical hybrid CRP and conventional CRP scheme were selected according to the design and calculated results.and then the hydrodynamic performance model tests were carry out in cavitation tunnel to further analyze the characteristics of the hybrid CRP’s flow field and the influence of power ratio on the efficiency.The flow field of the three schemes was measured by LDV method and compared with the CFD simulation results.The flow characteristics of the different schemes and its energy-saving mechanism were analyzed.