Numerical simulation on magnetohydrodynamic power generation channel of scramjet

超燃冲压发动机磁流体发电通道数值模拟研究

The reverse magnetohydrodynamic(MHD)energy bypass technology is a promising energy redis⁃tribution technology in the scramjet system,in augmented with a power generation equipment to supply the neces⁃sary long-distance flight airframe power.In this paper,a computational model of the scramjet magnetohydrody⁃namic channel is developed and verified by using the commercial software Fluent.It is found that when the mag⁃netic induction intensity is 1,2,3,4 T,the power generation efficiency is 22.5%,22.3%,22.0%,21.5%,and decreases with the increase of the magnetic induction intensity,and the enthalpy extraction rate is 0.026%,0.1%,0.21%,0.34%,and increases with the increase of the magnetic induction intensity.The deceleration ef⁃fect of electromagnetic action on the airflow in the power channel increases with the increase of magnetic induc⁃tion intensity.The stronger the magnetic field intensity,the more obvious the decreasing effect of fluid Mach num⁃ber in the channel.The power generation efficiency decreases as the magnetic induction intensity increases and the enthalpy extraction rate is reversed.As the local currents gathering at inlet and outlet of the power generation area,total temperature and enthalpy along the flow direction do not vary linearly,and there are maximum and minimum values at inlet and outlet.Increasing the number of electrodes can effectively regulate the percentage of Joule heat dissipation,which can improve the power generation efficiency.

磁流体动力学(MHD)反向能量旁路技术是超燃冲压发动机系统中一种很有前途的能量再分配技术,它与发电设备相结合,为长距离飞行提供必要的机身动力。本文通过使用商业软件Fluent建立并验证了超燃冲压发动机磁流体发电通道的计算模型。研究发现,当磁感应强度为1,2,3,4 T时,发电效率分别为22.5%,22.3%,22.0%,21.5%,且随磁感应强度的增加而降低,焓提取率分别为0.026%,0.1%,0.21%,0.34%,随磁感应强度的增加而增加。电磁作用对发电通道内气流的减速能力随着磁感应强度的增大而增大。磁场强度越强,马赫数的降低效果越明显。发电效率会随着磁感应强度增大而降低,焓提取率则会随着磁感应强度增大而增大。由于局部电流聚集在发电区域进出口,沿程方向的总温、总焓并非呈线性变化,在进出口存在极大值与极小值。增加电极数量可以有效调节焦耳热耗散的占比,从而可提高发电效率。