Research on Ducted Propeller and Rudder Interactions in Extreme Conditions

摘要

This paper presents the results and analyses of a combined numerical-experimental study into the performance of threerntypes of rudder to quantify the interactions between propeller, nozzle and rudder at extreme rudder angles. Conventional,rnflapped and triple rudders are studied numerically as well as experimentally to evaluate the drag, lift and momentrngenerated by the rudders at moderate to extreme rudder angles and at forward propeller shaft speeds and inflow speeds.rnThe experiments were carried out to evaluate the suitability of the three rudder types for a proposed cargo carrier in termsrnof controllability. The experiments were carried out at the self-propulsion condition of the model equipped with twinrnstock ducted propellers along with each of the rudder systems. An extensive numerical study was carried out to evaluaternthe performances of the three rudders in terms of flow velocity, pressure and wake fields. Drag, and lift for differentrnangle of attacks are obtained for complicated propeller-nozzle-rudder arrangements. Investigations are carried out tornstudy the effects of the interaction of the rudder with the propeller-nozzle assembly at extreme rudder angles at high asrn±40°. For simplicity, the geometry of the vessel was not modelled in these simulations.rnThe experimental results are presented along with the computational results for all three rudder cases. The lift and dragrnmeasurements are in good agreement with the corresponding predictions for each of the rudder arrangements. The mutualrninteractions between the rudder and the propulsion system were captured in the simulations and were comparable withrnthe corresponding measurements. The research reveals the nature of the velocity and pressure fields due to the complexrninteraction between the propeller, nozzle and rudders at extreme rudder angles. It is expected that the currentrninvestigation will assist naval architects, at the early design stage, to select the rudder type for their ships such thatrnsuitable maneuvering characteristics are obtained and stringent IMO maneuvering criteria are met.