Prediction Of Hydrodynamic Performances And Noise Of Ducted Propeller

With the ship energy saving got more and more attention, ducted propeller with its highpropulsive efficiency has got a wide range of interest and has been applied in many ships,especially the ships with heavy loading. This article was on based the velocity potential panelmethod to compute the steady and unsteady hydrodynamic performance of the ordinarypropellers and the ducted propeller, in this article the noise characteristics of the ordinarypropeller and the ducted propeller in non-uniform flow field were also computed, thefollowing tasks were done:Firstly, in this paper we have studied on the ordinary propeller panel method deeply andon the basis of this theory we used this method to compute the ducted propellers. In this paperwe have studied on the ordinary propeller panel method deeply and on the basis of this theorywe used this method to compute the ducted propellers. The influence of the duct and thepropeller was considered by the indirect interference model instead of the directlyinterference model, we computed the induced velocity to replace the interference. Wecomputed the Ka4series propeller with this method to get their open water performance anddrew a series of open water performance curve by the thrust coefficient and torque coefficientwhich calculated under the different advance coefficient. Compared these dates with theexperimental values and approved the method in this article could apply to the engineeringpractice. The different pitch of screw was also taken into consideration to analyze theinfluence to the hydrodynamic performance and the pressure distribution on the duct. Thegeometry parameters were changed to compare their influence to the dynamic performance.Secondly, in this article the unsteady performance of the ducted propeller was computedby the panel method which based on the velocity potential and the influence between the ductand the propeller was instead by the induced velocity. The program provided by this articlecould forecast the thrust and the torque of the ducted propeller when it working in thenon-uniform flow field and get the pressure distribution on the duct. At last, the impact of theduct on the inflow was also computed.In the article, with the given wake, the unsteady performance was computed and the datewas compared with the reference value. Through the comparison, the result in this article wasproved to be accurate and satisfied. At the end, in this article both the ordinary propeller and the ducted propellernon-cavitation noise were calculated. The unsteady force was calculated by the panel methodand the acoustics part was calculated through the FW-H equation and its time domainsolution. As the velocity on the propeller was much smaller the sound velocity in the water,so the quadrupole source was negligible. The far field noise could be computed by thenegligible of the monopole and the dipole.