Marine Propeller Optimization And Performance Analysis Of Additional Energy-saving Device

The concept of green development has brought about a growing importance for energy saving and emission reduction technologies.This presents a significant challenge for ships,which are major energy consumers.Therefore,this paper proposes a hydrodynamic energy saving scheme that combines a high-efficiency propeller,propeller boss cap fins,and a pre-duct,and based on CFD method to realize the propeller efficiency optimization and hydrodynamic performance correlation analysis with additional propeller boss cap fins and pre-duct.The numerical simulation method of propeller hydrodynamics is studied and validated.The JQ-5-81 propeller is used as the research object,and different turbulence models are compared to determine the accuracy and applicability of the SST k-ω model.The results show that the selected numerical method is reasonable and reliable,and the SST k-ω model has high accuracy.Furthermore,the errors between the numerical calculation results and the experimental results are analyzed to verify the findings.The key parameters of propeller performance are optimized.Through the analysis of propeller parameters,the influence of main parameters on propeller hydrodynamic performance is discussed.It is found that pitch is the most significant parameter affecting propeller hydrodynamic performance,while trim has little effect.Taking the radial distribution of pitch parameters as the optimization variable,the open water efficiency as the optimization objective,and the thrust coefficient not lower than the original propeller as the constraint condition,the propeller was optimized by using CFD technology and orthogonal experimental design,and the design scheme with better efficiency was obtained.Propeller boss cap fins are installed on the optimized propeller.The energy-saving mechanism of the propeller boss cap fins is analyzed.It is found that the installation of the propeller boss cap fins can weaken the hub vortex strength,recover the wake energy,eliminate the low pressure area on the hub boss,and generate negative torque on the fin blade,so as to improve the efficiency.Based on the study of its mechanism,the influence of propeller boss cap fins installation angle,axial position,diameter and other parameters on the overall hydrodynamic performance is analyzed.The results show that within the range of the studied parameters,when the installation angle is close to the pitch angle at the root of the propeller,the energy saving effect is the best;The increase of axial position can improve the energy saving effect to a certain extent,but when it increases to a certain distance,the propulsion efficiency under partial advance coefficient will decrease;The propeller boss cap fins diameter at 0.26 D has higher energy saving effect.On the basis of installing the propeller boss cap fins,the pre-duct is further installed in front of the propeller.Through the analysis of the energy-saving mechanism of the pre-duct,it is found that it can change the inflow velocity of the propeller,thus affecting the hydrodynamic performance of the propeller and the boss cap fins,and under the action of the propeller rotation,it can generate additional thrust under the low advance coefficient,so as to improve the overall efficiency.Through the analysis of the two types of acceleration pre-duct and deceleration conduit,as well as the parameters such as the angle of attack,diameter,length and position of pre-duct,it is found that the energy-saving effect of acceleration pre-duct is better than that of deceleration conduit within the scope of study;The energy-saving effect of the pre-duct with 0 ° angle of attack is better;With the increase of the diameter of the pre-duct,the energy-saving effect is gradually improved;Lengthening and shortening the pre-duct will reduce the energy-saving effect on the basis of keeping the maximum thickness of the pre-duct section unchanged;The closer the duct position is to the propeller panel,the more obvious the energy saving effect is.Finally,the influence of different combinations of optimized propeller,propeller boss cap fins and pre-duct on the overall performance is analyzed,and the optimal combination of energy-saving schemes under different forward speed coefficients is given.