CFD Simulation Of Marine Propeller Open Water Performance

With the tendency of large-scale and high-speed of the of modern merchant ships,the load of its propeller is getting heavier and heavier which results in the cavitation and vibration deterioration of ships. Cavitation and vibration of ships have increasingly become the concern of propeller designers. Traditional methods on study of propeller performance can no longer meet the demand of the new generation of propeller. Computational Fluid Dynamic(CFD) method can achieve the visualization of calculation results;overcome shortcomings, such as long timing and high cost of tank trial and greatly cut down the development cycle. Because of the large amount of information in computing results,this method provides high reference value for the study of cavitation and vibration caused by propeller.This paper employs CFD software FLUENT, to numerically compute the viscous flow field of propeller under open water. Firstly,it builds up a three dimensional model of the propeller with the help of Pro-E and Gambit then designs the model of propeller and the computational field by making use of periodic boundary conditions. By comparison with experiment data, the numerical results (thrust coefficient and torque coefficient) are well evaluated with average relative error less than 10%,meeting the engineering accuracy.Four kinds of turbulence models are employed respectively for computation, including standardκ-εmodel, RNGκ-εmodel. Realizableκ-εmodel and Reynolds Stress model. In general,Reynolds Stress model is more accurate than other three models. Full channel and single channel are employed respectively, verifying the feasibility of the single channel method. With the single channel method, computing efficient is enhanced and computing time is largely saved.The surface pressure and the wake flow of propeller are studied and the probable areas that cavitation takes place is preliminarily analyzed. The study of the wake flow of propeller verifies that the suction effect of propeller is enhanced under heavy load and wake contraction occurs. Meanwhile it indicates that radial induced speed appears to be deceased with the increase of advance coefficient.Uncertainty analysis of CFD simulated results is carried out through the procedures proposed by International Towing Tank Resistance Committees.Grid studies are conducted using three sets of grid with grid refinement ratio rk=(?).By calculating,the uncertainty of KT is 0.0262 and KQ is 0.0384.The corrected uncertainty of KT is 0.00522 and KQ is 0.0174.|E|<UV shows that validation of CFD simulated results is achieved, that is to say,the KT,KQ in this paper’s refinement is reliable.