The Design For The Axial-Pump Of An Amphibious Vehicle Using Modified Lifting Method Based On CFD

The study on amphibious vehicles, known as the main transportations in the ocean era, have attracted broad attention, and the design method for their propulsion unit are improving as well. The lifting design method is the conventional approach to the axial-pump of the water-jet propulsion for amphibious vehicle. It features with simplicity in design process but has the greatest disadvantage that the design should be referred to a parent pump with similar performance, which leads to the fault in flexibility of design.With the rapid progress of computer technology and mathematical algorithms, CFD methods have been widely applied to many fields of traditional hydrodynamics. By means of software ICEM and CFX, this paper attempts to improve the traditional lifting design method by correcting the aforementioned disadvantage. The design for the axial-pump of the water-jet propulsion for an amphibious vehicle has been carried out to verify the feasibility and accuracy of the improved method.Before the above attempt is made, it is necessary to verify the accuracy of the CFD method for the numerical prediction of hydrodynamic performances of surface vehicles and underwater propulsor. In this paper, several cases including Wigley ship,4119propeller, the ducted propeller "JD Duct+Ka propeller" and the axial-pump020Q84, have been selected to verify the feasibility and accuracy. Several conclusions can be drawn as follows:the relative errors for the total drag coefficient are less than10%and the simulated flow regime agrees well with the experimental results; the relative errors for the hydrodynamic parameters is less than10%while the average is less than5%, except for those at very low and high velocities.Based on the CFD method, the disadvantage that the design is limited by the parent pumps has been improved by the correcting the geometric parameters of blades obtained by the lifting design method. The key to the improvement is that the CFD simulation could play the role of model test, which makes it possible to fasten the compare and decision of the optimum proposals. To verify the feasibility and accuracy, the improved method has been applied to the design for the water-jet propulsion unit of an amphibious vehicle. Finally we found that, the performance of the axial-pump using the improved lifting design method based on CFD can attain the prospective goal, even there exists great difference of performances between the parent pump and the designed one.