The Research On The Hydrodynamic Performance Of Contra-rotating Propellers Based On CFD Methods

In recent years, People have put higher requirement on the ship speed. Especially in the military, for the experts high speed ship has been a major topic. In civilian areas, due to the accelerated pace of life and the lack of energy, people give higher expectation to the ship which has the higher speed and better energy-saving. The propeller As the core of ship propulsion, has been paid high attention both in military and civil areas.The contra-rotating propellers as one of special propellers which has the most effective method to improve the ship speed and propulsive efficiency, is getting more and more attention. But there is few qualitative research to it. Based on the CFD method, this paper mainly studies on the hydrodynamic performance of the contra-rotating propellers. The details are as follows:1、The numerical calculations are conducted for B4-40 which is one of the B series propellers. The open water performance of B4-40 is studied and compared under Standard k-ε、RNG k-ε、RSM、SSTk-ω four kinds of turbulence models. Considering the calculation accuracy and time efficiency, the SSTk-ω is the best model of the four. Moreover, the stress characteristics and wake field of B4-40 are analyzed as well.2、Then CFD numerical calculation of the contra-rotating propellers which is made up with B series propellers is completed. After comparing the result of CFD numerical calculation between RSM turbulence model and SSTk-ε turbulence model, the SSTk-ω model has the better answer. Because of the influence from the front propeller, the after propeller has obvious calculation error compared with single propeller. In order to reduce the numerical error the dynamic grid method should be used.3、Two groups of contra-rotating propellers are chosen to do CFD numerical calculation. After comparing and analyzing the results, we can get the best parameters of pitch ratio L/D and diameter ratio Da/Df. At the same time, to study the reasons for the different results the results of numerical calculation and the wake field of contra-rotating propellers are compared.4、Two best contra-rotating propellers are selected to compare with the B4-78 and B4-76.8 propeller at the open water performance respectively. The open water efficiency of the contra-rotating propellers lower than single propeller’s, but the thrust is far greater than the latter under the same J. In the same power coefficient, the open water efficiency of contra-rotating propellers is better than single propeller’s. The open water efficiency is improved more than 7.46%, which shows the high open water efficiency of contra-rotating propellers.