Hydrodynamic Performance Analysis and Optimization Design of Mechatronic Ducted Propeller with CFD

Abstract

Computational fluid dynamics (CFD) is applied in the whole process of hydrodynamic performance analysis and optimization design of a mechatronic ducted propeller. The open water characteristics of a ducted propulsor with a stator behind its rotor are calculated,hydrodynamic force coefficients show good agreement with the experiment data,which indicates the validity of CFD method. The hydrodynamic performances of the preliminary design mechatronic ducted propeller are calculated with the same CFD method,including putting forward the major geometrical dimensions of the shrouded duct in hydrodynamics terms by simulation,and validating the calculated results by changing the mesh type and distribution. An optimization design,which improves the tip flow and enhances the open water efficiency,can be achieved by shortening and thickening the ring and changing the blade geometry correspondingly after analyzing the effect of ring without winding to the flow pattern of tip clearance and hydrodynamics of ducted propeller,as to the component duct or propeller itself and to the whole geometry. Numerical simulation is conducted to the secondary design ducted propeller under design and off-design conditions. The calculated pressure distribution around the ring is compared with that of the preliminary one,and comparison of the propulsion performance is also completed with the second one to the first one,and to the experiment simultaneously. It is shown that the use of CFD to the preliminary design and performance analysis of the duct propulsor is effective. With a large radial distance of the clearance,the pressure reduction in the clearance and the range of local stagnation flow region will be large also. The longer the ring in the axial direction is,the more vortexes in the turnaround tip flow will be. The existence of the ring is beneficial to axial force of the duct,but not to the blade,as it makes the efficiency of the ducted propeller lower. The thrust coefficient of the redesigned ducted propeller is higher than that of the first one,moreover,the torque coefficient is lower,and the open water efficiency is higher,thus showing the correctness of the improvement.