Open Water Performance Of CRP And Its Application In A Planning Craft

As a propulsor,propeller has been widely concerned since it appeared.In recent years,it is highly demanded for speed and transverse stability of marine vehicles,which results in more requirement on propellers.The counter rotating propeller is designed for this purpose,which is particularly associated with the propulsion of high-speed yacht,warships,submarines and other carriers.In this paper,the hydrodynamic performance of the propeller is studied based on the CFD method.The main contents can be divided into three parts as follows.First of all,a benchmark CRP6(Contra-Rotating Propeller)composed of DTMB3686,DTMB3687 is studied.In which,the open water performance of propeller CRP6 is calculated.Its numerical results are compared with experimental data and agreed well.This validates the numerical methods for prediction hydrodynamic performance of CRP and helps to investigate its flow character.Secondly,the optimum ratio of distance L to diameter D(where L is the distance between forward propeller and aft propeller)is discussed.Twelve groups of CRP models with different L/D are built.At the same working condition J=0.7,the propeller thrust,torque and efficiency are calculated and compared.One CRP with the zero torque is chosen as the optimum ratio of L/D.The open water performance curve of this optimum CRP is calculated.By comparing the performance curves of this CRP with the single propeller,it is found that the efficiency of the CRP is improved,the transverse roll of the hull is reduced,and the lateral stability of the ship is increased.Finally,the optimum CRP is applied to a planning craft.The cruise speed of this planning craft is 25knot.In the first place,the resistance of this planing craft at this speed is calculated with numerical method and check node method respectively.The results of resistance of numerical calculation is compared with the theoretical method and its error is 2.24%.Then,according to the resistance,the propeller is designed.And the hydrodynamic performance of the planning craft appended with the CRP is investigated and its flow field is provided in detail.