Assessment of the Improved Cavitation Model and Modified Turbulence Model for Ship Propeller Cavitation Simulation

Abstract

To assess the effectiveness of the adopted improved Sauer cavitation model and modified shear stress transport turbulence model for ship propeller cavitation simulation,and verify the applicability of the rule when σσi,the pressure coefficient of the blade tip section is relative unaltered to determine the cavitation inception,comprehensive validation and analysis of E779A propeller’s sheet cavitation pattern,cavity area,pressure coefficient distribution of the blade section,thrust and torque breakdown performance curves and its inception cavitation index are conducted under lightly,moderately and heavily cavitation levels.Results show that,under moderately cavitation level condition(0.1 ≤Ac/A00.25),simulated cavity area agrees very well the experiment and being better than that in opened research papers,while a little smaller than the test for the lightly cavitation level(Ac/A00.1) due to wall roughness effect,and over-prediction for heavily cavitation(0.25≤Ac/A00.5) because of the bubble cavitation area included.Under both of the design and un-design conditions,the predicted beginning points of thrust decline induced by cavitation are the same as experiment,while the slope indexes of thrust and torque are bigger.Under J=0.77 condition,the calculated cavitation inception number determined by the rule is 3.25 and just differs by 0.6% to its experiment.All the results above are concluded that the adopted numerical models are absolutely valuable for propeller cavitation simulation under moderately cavitation level associated with satisfactory results.Additionally,the inception rule is positively useful to determine the cavitaion inception and predict the inception bucket next after back inception index of the 0.88R section(for low skew angles) or 0.7R section(for highly-skewed propeller) being obtained.With this method,the critical inception speed prediction of warships is no more difficult.