Influence of magnetohydrodynamics configuration on aerothermodynamics during Martian reentry

This paper investigates the role of magnetohydrodynamics (MHD) on the aerothermodynamics (ATD) of a representative entry vehicle while flying into the Martian atmosphere. By strategically placing a flight-ready superconducting magnet at varied positions in the Schiaparelli reentry capsule of the ExoMars mission, we discern its impact on essential flow properties. The primary consequence of MHD during atmospheric entry is the generation of the Lorentz force, which increases the shock standoff distance resulting in a reduction of the heat flux on the spacecraft by pushing high-energy plasma particles away. Through different magnet configurations, three distinct cases are formed to comprehensively understand the effects and implications of each setup. The study is performed using the COOLFluiD MHD for EnTries, an in-house ATD solver. For case 1, the magnet's placement behind the ExoMars forebody at the stagnation point reduces the heat flux. In case 2, the magnet's relocation to the shoulder region explores its potential to mitigate communication blackouts by influencing the wake region's flow. However, this positioning also induces shock bending, leading to variations in post-shock species mass fractions and heat flux spikes in the post-shock region. Case 3, involving an additional magnet where the shock bends in case 1, showcases a consistent increase in shock standoff distance across the forebody, providing a longer relaxation zone for species equilibration. Our findings highlight that while the strength of the applied magnetic field is crucial, the magnet's size is equally pivotal in determining ATD behavior. Case 3 emerges as the most promising configuration, consistently reducing heat flux across the forebody and maintaining it in the afterbody. This study underscores the potential of multi-magnet configurations as next-generation MHD heat shields for Martian atmospheric entry, emphasizing the criticality of magnet placement and configuration in enabling future MHD-enhanced deep space exploration missions.本论文研究了磁流体动力学（Magnetohydrodynamics, MHD）对典型进入飞行器飞入火星大气层时的气动热力学（Aerothermodynamics, ATD）特性的影响。通过在ExoMars任务的斯基亚帕雷利（Schiaparelli）再入舱的不同位置合理布设飞行就绪型超导磁体，我们探究了其对关键流动特性的作用效果。大气再入过程中磁流体动力学的核心效应是洛伦兹力的产生：该力可增大激波脱体距离，通过将高能等离子体粒子推离航天器表面，从而降低航天器受到的热流密度。本研究通过设置不同的磁体布局，构建了三类典型工况，以全面理解各布局的作用机制与实际效果。本研究采用专为再入飞行器气动热力学开发的自研求解器COOLFluiD MHD for EnTries开展数值模拟。工况1中，磁体布置在ExoMars前体的驻点位置，可有效降低热流密度。工况2中，将磁体移至肩部区域，可通过影响尾流区流动，探索其缓解通信黑障的潜力；但该布局同时会引发激波弯曲，导致激波后组分质量分数发生变化，并在激波后区域出现热流尖峰。工况3在工况1中激波弯曲的位置增设额外磁体，可使前体区域的激波脱体距离持续增大，为组分平衡提供更长的松弛区。研究结果表明，尽管外加磁场强度至关重要，但磁体尺寸同样是决定气动热力学特性的关键因素。工况3被证明是最具应用前景的布局，可持续降低前体区域的热流密度，并在后体区域维持该效果。本研究凸显了多磁体布局作为火星大气再入下一代磁流体动力学热防护系统的潜力，强调了磁体布设位置与布局方案对于支撑未来磁流体动力学增强型深空探测任务的关键意义。