Performance Prediction Of One Ship's Contra-Rotation Thruster Based On CFD

The advancement of the world economy and science and technology has led to the vigorous development of the shipbuilding industry.which has put forward great requirements for the maneuvering performance of the ship.As an auxiliary device of the ship,the thruster is favored by experts and researchers in the field for its precise positioning,good maneuverability,timely avoidance of hidden reefs and overcoming nearshore effect.With the diversification and enlargement of ships,ordinary propellers have not satisfied the status quo,people turn their targets to the counter-rotating propellers,because the rear propellers of the counter-rotating propellers can absorb the eddy current energy of the front propellers,thereby improving energy efficiency and effectively improving the ship's rapidity and propulsion efficiency,and to solve the problems faced by the single propeller.Based on the CFD numerical simulation,the performance prediction of the propeller thruster was assembled,which provided a theoretical reference for the ship's power design.In view of the research objectives mentioned above,the specific research contents of this paper are as follows:1.3D design according to manufacturer's requirements and relevant data.Then the calculation domain and mesh are divided into the propeller,and the CFD numerical calculation is carried out under four different turbulence models of Standardk-?,RNGk-?,SSTk-? and RAM.The calculation results are compared with the experimental data,and the propeller paddle is analyzed at the same time.Leaf pressure characteristics and wake field distribution prove whether the designed propeller meets the design requirements and prove the feasibility and reliability of numerical calculation,which lays a foundation for subsequent study.2.The matching parameters of counter-rotating propeller were designed,such as the diameter of the blade before and after the fault ratio,leaf angle and blade spacing,Then,based on the research of the single propeller,the numerical simulation of the propellers under different speed coefficients is carried out.The calculated results are compared with the experimental data to analyze the error,and on the other hand,the open water performance of the single paddle and the counter paddle is compared and analyzed.3.In order to more accurately analyze the performance of the thruster and the surrounding flow field distribution,firstly,a simplified model of a ship was constructed,and the flow field velocity distribution of the ship model and the hull pressure distribution were analyzed by numerical calculation.to lay a foundation for the research of bow thruster.Subsequently,a ship model equipped with a single propeller and a counter-propeller was built,and CFD numerical calculations were performed for the assembly counter-rotating propeller thruster and the single propeller thruster respectively,and the single-row thruster was compared by analyzing the wake field and the performance of the rotary thruster.Through the above numerical calculations,the results show that:1.CFD numerical model was carried out by four turbulence models.The calculated results were compared with the experimental data.It is concluded that SST6)- and RAM are in the best agreement with the experimental data,satisfying the design requirements.Considering the performance and calculation time of the computer,the SST6)- turbulence model was the best model.In the subsequent calculation of the counter-rotating propeller and the thruster,the SST6)- turbulence model was used for calculation.2.On the basis of the single-blade research,the research on the rotary propeller was further studied.The numerical calculation results were compared with the experimental results to show that the thrust coefficient and torque coefficient of the propeller are greater than 50% of the single propeller,and the open water efficiency ratio is 1.4%~15.46% higher than that of the single propeller,and the introduced power coefficient also proves the superior performance of the propeller.Comparing the single-blade and counter-rotating blade pressure and wake field,when the speed coefficient is small,the pressure of the single-blade propeller is greater than the blade back,which is the opposite of the counter-rotating propeller,and at the same time,the tendency of the turning tail to shrink inward is large.3.By simulating the flow field of the ship without the thruster,it is found that the speed and pressure of the hull are mainly distributed at the bow and the bottom of the ship during the navigation.Therefore,when designing the hull structure,the bow and the bottom of the ship need to be strengthened;Numerical calculations are carried out for the assembled single propeller and counter-propeller thruster ship models.It can be seen from the trace diagram of the flow field and the longitudinal and axial velocity contour map that the thrust generated by the propeller thruster is significantly greater than that of the single propeller thruster.At the same time,the speed at the diagonal of the hull is large,indicating that the hull generates steering force under the action of the thruster for the U-turn;and the steering effect of the counter-rotating propeller is better than that of the single propeller.In summary,the rotary propeller thruster exhibits superior performance.