Tuning a precession driven flow for optimized magnetic field generation in the DRESDYN dynamo experiment.

宇宙磁场是无处不在的现象，在所有尺度上都可以观察到，从行星和恒星到星系和星系团。这些场的起源涉及通过导电流体或等离子体的复杂流动形成电流。在实验中也已经观察到通过这种发电机效应的流体流动诱导的磁场，然而，由于实验室中可用的尺度明显较小，因此需要相当大的技术努力。在亥姆霍兹-德累斯顿-罗森多夫中心（HZDR）进行的DRESDYN项目（用于DYNamo和热工水力研究的德累斯顿钠设施）为各种致力于地球和天体物理磁流体力学问题的液体钠实验提供了一个新的平台。 该项目中最雄心勃勃的实验是目前正在建设的进动驱动发电机实验，该实验由一个充满液体钠的圆柱体组成，该圆柱体同时围绕两个轴旋转。本提案涉及数值和实验研究，旨在发现的参数制度，将允许发电机行动在计划的实验和优化的进动驱动流，以改善发电机过程。 为此，我们追求一种特殊的方法来提高强制效率，并通过考虑安装在圆柱形容器的盖子的内侧上的径向挡板来控制大规模的流型。 固体挡板与内部流体流的相互作用提出了一个复杂的流体力学问题，只能通过以下补充的数值和实验方法来解决。 相应的模拟和模型实验将为今后的大规模液体钠发电机实验提供基础。

Cosmic magnetic fields are ubiquitous phenomena that are observed on all scales, from planets and stars to galaxies and clusters of galaxies. The origin of these fields involves the formation of electrical currents by means of complex flows of conducting fluids or plasmas. Fluid flow induced magnetic fields via this dynamo effect have also been observed in experiments, which, however, require considerable technical efforts due to the significantly smaller scales available in the laboratory. The project DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies) conducted at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) provides a new platform for a variety of liquid sodium experiments devoted to problems of geo- and astrophysical magnetohydrodynamics. The most ambitious experiment within this project is a precession driven dynamo experiment currently under construction which consists of a cylinder filled with liquid sodium that simultaneously rotates around two axes. The present proposal addresses numerical and experimental studies aimed at the discovery of parameter regimes that will allow dynamo action in the planned experiment and at optimizing the precession driven flow in order to improve the dynamo process. For this purpose, we pursue a particular approach to increase the forcing efficiency and to control the large scale flow pattern by considering radial baffles mounted onto the inner side of the lids of the cylindrical container. The interaction of solid baffles with an internal fluid flow presents a complex fluid mechanical problem that can only be addressed by following complemental numerical and experimental approaches. The corresponding simulations and model experiments will provide the basis for future experimental campaigns of the large scale liquid sodium dynamo experiment at HZDR.