电磁流体表面推进是在推进单元周围的导电流体中(海水、等离子体等)激励出电磁体积力,并利用电磁体积力的反作用力达到推进的目的.基于电磁场和流体力学的基本控制方程,采用有限体积法对电磁流体表面推进的效果进行了数值模拟研究,分析了在不同姿态(攻角)和不同电磁体积力的作用下,航行器周围流场结构的变化规律和推力的变化特点.研究结果表明:沿航行器表面分布的电磁体积力可以有效地改变流体边界层的结构,并能向流体边界层传输动量与能量,从而使航行器获得所需的推力.流体对航行器的黏性阻力和压差阻力的影响随作用参数的增大而减弱,且推力系数和作用参数的关系渐由非线性趋于线性,航行器所获得的推力大小主要取决于电磁体积力的强度.在航行器有攻角运行的情况下,电磁流体表面推进方式还能有效地提升航行器的升力.因此,将航行器表面设计为推进单元的工作面,对航行器整体结构的优化设计和推进效率的提高有一定意义.
The electromagnetic hydrodynamics(EMHD) propulsion by surface is performed through the reaction of electromagnetic body force,which is induced in conductive flow fluid (such as seawater,plasma and so on) around the propulsion unit.Based on the basic governing equations of electromagnetic field and hydrodynamics,by numerical simulations obtained by the finite volume method,the characteristics of flow field structures near the navigating and the strength variation of propulsion force are investigated at varying positions (the angle of attack).The results show that surface electromagnetic body force can modify the structure and the input energy of flow boundary layer,which enables the navigation to obtain the thrust.With the increase of interaction parameter the effect of viscous resistance and pressure drag to navigating decrease and the nonlinear relationship between propulsion coefficient and interaction parameter tends to be linear gradually.The strength of propulsion force depends mainly on the electromagnetic body force.The lift force can be improved effectively through the EMHD propulsion by surface at an angle of attack for navigating.The navigating surface can be designed as working space of propulsion units,which is of certain significance for optimizing the whole struction and improving the efficiency.