分别以推进器中的流体和车体为对象建立了受力模型,指出了推进器对车体阻力的直接和间接影响.直接影响有3种情况:进水口使迎水面减少导致阻力增加、进水口使车底边界层由层流变湍流导致阻力增加,以及推进器中水的重量导致车体阻力增加;间接影响则导致车辆产生尾倾和首倾.基于局部平衡假设,推导了不同速度时两栖车辆边界起始网格的大小变化规律,在对喷水推进器作了适当简化后,建立了两栖车辆水上仿真计算的边界模型.分析结果表明,推进器可使车体在水上的阻力增加15%以上,适当增加车体的攻角有助于提高推进器的工作效率.
The fluid in the hydraulic propeller and the hull were respectively taken as analytical objects to model the forces exerted on them,and the model demonstrated that the propeller could affect the resistance of the hull directly and indirectly.The direct influence includes three cases that increase the resistance of the hull,i.e.the water inlet of the propeller decreases the lifting surface area,the water inlet makes laminar flow become turbulent flow,and the weight of the water in the propeller makes the hull heavier.The indirect influence may make the attack angle increase or decrease.The change law of the initial size of grid used to mesh the hull was derived from the local equilibrium hypothesis.The boundary model for simulation of the amphibious vehicle running on the water was set up after simplifying the hydraulic propeller.More than 15% resistance was added to the hull because of the hydraulic propeller's influence,and an appropriate increase of the hull's attack angle help to improve the working efficiency of the propeller.