摘要
电磁力可有效对流体流动进行控制,增升减阻,抑制流动分离,制约其推广应用的瓶颈为控制效率问题。为提高其控制效率,需要深入研究电磁与流场的相互作用及其能量传递过程。对电磁力增升减阻的控制效率问题进行了数值研究。根据能量守恒定律,推导电磁力控制能耗,基于升力和阻力计算节省能量。定义电磁力的控制效率为η=能量节省/电磁力控制所需能耗,研究电磁力控制过程,分析其能量损耗,为电磁力控制效率的提升提供理论基础。研究结果显示在控制开始阶段,电磁力控制能量的损耗主要体现流体动能损耗,其最高损耗率可达95%,其次体现在焦耳热上,最高可达28%;随着时间推移,流体动能损耗η2下降,电磁力控制效率η及焦耳热损耗η1增加,控制效率η在控制结束时增加到了33%。其机理为流动动能损耗与边界层速度的改变程度紧密相关,电磁力作用一段时间后,边界层速度剖面图再无明显变化,因此流体动能损耗下降,在控制开始阶段流体动能损耗为主,流体动能损耗为主其损耗的下降会提升电磁力的控制效率。
Lorentz force can control the flow of low-conduction fluid effectively,however,the problem of low control efficiency is the main bottleneck to restrict its application,in order to enhance the Lorentz force control efficiency,numerical research of Lorentz force control efficiency had been carried out base on the flow control around hydrofoil using Lorentz force control. Energy consumption equation of Lorentz force control had deduced on the basis of the law of energy conservation,the amount of saving energy had calculated by using the lift and drag of hydrofoil. The control efficiency（ η） of the Lorentz force is defined as the ratio between saved power and used power.The research results had shown that most of energy is wasted at fluid kinetic energy and joule heat within the initial0. 2 s,the loss rate could reach 95%. Secondly,the energy is wasted at joule heat,the loss rate could reach28%. As the active time pass by,the dissipation of fluid kinetic energy is decline,the control efficiency and Joule heat loss rate are increased,the control efficiency is increased to 33% at the end of active time. The mechanism is that the loss rate of fluid kinetic energy has a close relationship with change scope of boundary layer velocity,while the velocity profile of boundary layer does not have a significant change after a spell of Lorentz force activate,the loss rate of fluid kinetic energy is declined,which will enhance the control efficiency of Lorentz force.
出处
《科学技术与工程》
北大核心
2015年第27期1-6,共6页
Science Technology and Engineering
关键词
流动控制
电磁力
翼型绕流
控制效率
control efficiency flow control Lorentz force flow around hydrofoil
