Research Of CFD Simulation Method For Propeller Performance In Non-uniform Inflow

As the applications of CFD (Computational Fluid Dynamics) method tomarine propeller simulation are increasing nowadays, CFD method isgradually taking place of potential flow methods and becomes the mainapproach to the prediction of marine propeller performances. The predictionof propeller performance in non-uniform inflow is one of the importantworks for marine propeller simulation. It is worthwhile to work on finding aneffective way to predict blade average force, unsteady forces and cavitationprecisely.For the CFD prediction for the performance of a propeller workingbehind the ship, the usual way is to set the hull in front of the propeller as thewake generator, which complicates the model building process and makes itnecessary to accurately simulate the interaction between hull and propeller. Ifthe hull is excluded from the model and the wake velocity distribution isspecified on the inlet boundary directly, the preliminary issue to address ishow to eliminate the dissipation of wake velocity when the flow convectsfrom the inlet to the propeller disk. Therefore, the research on CFDsimulation of the unsteady propeller performance in non-uniform wake bymeans of specifying the wake velocity distribution on the inlet is conductedin this study. The dissipation of wake velocity is reduced by shortening the distance between the inlet and the propeller disk. Meanwhile, the inducedvelocity of propeller is added to the inlet to reduce the error caused byshortening the size of computational domain. The comparison of numericaland experimental results shows the proposed method is suitable forsimulating the propeller performance in single axial wake. The shortenedinlet distance reduces the velocity dissipation effectively and the introductionof propeller induced velocity at the inlet boundary improves the accuracy ofprediction for steady thrust and torque.For the ducted propeller in bollard condition, the CFD-predicted thrustand torque are sometimes inaccurate using the same way of CFD modelingfor J>0. In this study, the propeller induced velocity computed by using alifting surface code is added to the inlet and hence the size of computationaldomain reduced. The comparison of numerical and experimental resultsshows this method is able to improve the accuracy of prediction, reduce thesize of computational domain, and enhance the efficiency of simulation.