Effect of LN2 Sloshing on the Lateral Dynamic of HTS Pinning Maglev

Abstract

As an innovative maglev system, the high-temperature superconducting (HTS) pinning magnetic levitation (maglev) train achieves levitation and guidance through the interaction between the HTS bulks in the levitator and the permanent magnet guideway. To ensure that the HTS pinning maglev maintains a stable levitation working state, the ambient temperature of the HTS bulk must remain below its critical temperature. The current method is injecting liquid nitrogen (LN ₂ ) into the levitator's liquid tank for cooling. However, due to heat transfer, LN ₂ in the tank is not always fully replenished. External disturbances can cause LN ₂ sloshing, which affects the vehicle's dynamic performance. This issue remains underexplored by scholars. In this article, LN ₂ excitation is integrated into studying the dynamic performance of HTS pinning maglev for the first time. First, a spring–mass model is established to deal with the LN ₂ sloshing in the levitator equivalently. Computational fluid dynamics software verifies the feasibility of this model. The equivalent model is then integrated into the vehicle system to develop an HTS pinning vehicle dynamics model, which is validated by experimental data. Subsequently, the dynamic response of the vehicle and the levitators considering the LN ₂ sloshing is analyzed. Finally, the optimal LN ₂ filling ratio in the levitator is proposed from the perspective of dynamic performance optimization. The results show that the LN ₂ sloshing in the levitator has a particular influence on the lateral vibration, lateral displacement, and roll angle of the HTS pinning maglev vehicle. In addition, it is recommended to replenish LN ₂ when the filling ratio inside the levitator reaches 70%. This work enhances the understanding of the dynamic response of HTS pinning maglev trains under multiple excitations and provides a reference for refining HTS pinning maglev modeling.