Key Takeaways & Executive Findings
- •• Increasing suspension gap from 10 mm to 30 mm reduces head car lift by 12.43% and increases drag by 10.98%. • The tail car experiences the highest aerodynamic drag and underbody temperatures due to airflow deceleration. • U-shaped track constrains flow, creating strong vortex structures that significantly affect aerodynamic performance. • IDDES simulations reveal unique underbody drag and aerothermal distribution patterns for HTS maglev trains.
Abstract
The suspension gap is a critical operational parameter for high-speed maglev trains and significantly impacts their aerodynamic performance. Based on an engineering prototype of the high-temperature superconducting (HTS) pinning maglev train, this study established a detailed three-dimensional model, and then the aerodynamic characteristics of the HTS maglev train at 600 km/h with suspension gaps of 10 mm, 20 mm, and 30 mm were simulated based on the improved delayed detached eddy simulation (IDDES) turbulence model and SST k- ω two-equation. The results demonstrated that the underbody design of the HTS maglev train leads to unique aerodynamic drag and aerothermal distribution phenomena. The head car experiences the smallest drag, while the tail car experiences the largest. The aerothermal temperature on the train's bottom surface progressively increases from the head to the tail. Additionally, the U-shaped track significantly constrains the flow around the train body, forming strong vortex structures. As the suspension gap increases from 10 mm to 30 mm, the airflow velocity in the train-track gap rises, reducing the underbody pressure and decreasing the lift of the head car by 12.43%. The drag of the head car increases by 10.98%, primarily due to changes in pressure drag. Additionally, the temperature at the underbody of the tail car rises further due to significant airflow deceleration. These findings provide valuable insights for advancing the engineering design and application of the high-speed HTS maglev technology.
1. Introduction
Magnetic levitation (maglev) technology achieves suspension, guidance, and propulsion in a non-contact manner, effectively avoiding issues such as wheel-rail adhesion and pantograph supply stability. It offers energy consumption reduction and efficiency improvement advantages, making maglev trains a promising option for ultra-high-speed rail transportation [1]. Countries such as Germany, Japan, South Korea, and the United States are actively researching high-speed maglev systems [2-4], while China has set a goal to develop a 600 km/h high-speed maglev transportation system [5, 6].
Existing high-speed maglev technologies are primarily categorized into three types: electromagnetic suspension (EMS) [7], electrodynamic suspension (EDS) [8, 9], and high-temperature superconducting (HTS) maglev [10]. The HTS maglev system achieves self-stable levitation through interactions between onboard superconducting bulks and permanent magnet guideways (PMG), while its liquid nitrogen cooling offers economic and environmental advantages over conventional low-temperature superconductors [11, 12]. The HTS maglev system features inherent stability, a simple structure, negligible magnetic drag in the direction of motion, and environmental friendliness, making it a key direction for developing high-speed maglev systems. In 2021, Southwest Jiaotong University created the high-speed HTS pinning maglev prototype vehicle and test track (as shown in Figure 1), with a design speed of 620 km/h [1]. Figure 1(a) shows that the test line is designed in a U-shaped track layout with a linear motor stator (LMS) and two PMGs on the ground. As shown in Figure 1(b), the engineering prototype has a side view, featuring a bogie frame covered with high-temperature superconducting levitators (HTSL), which are cryogenic containers equipped with superconducting bulks and liquid nitrogen for cooling. The distance between the bottom of the carriage and the PMG is defined as hc, which is 40 cm. Figure 1(c) presents the suspension gaps of the prototype under real operation conditions. The suspension gap of the HTS maglev can be designed through weight balancing and cooling in different magnetic field strengths, typically maintained at 10 −30 mm [13]. As the speed of maglev trains increases, their interaction with the surrounding airflow intensifies. A suspension gap between the train
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LI Zong-peng, PAN Yi-ming, WANG Xiao-fei, ZHAO Hong-min, DENG Zi-gang, ZHANG Wei-hua (2025). Aerodynamic characteristics of a 600 km/h high-temperature superconducting maglev train running in open air considering different suspension gaps. Journal of Central South University. https://doi.org/10.1007/s11771-025-6141-x
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Frequently Asked Questions
What is the effect of increasing suspension gap on the aerodynamic performance of the HTS maglev train?
Increasing the suspension gap from 10 mm to 30 mm reduces the lift of the head car by 12.43% and increases its drag by 10.98%, primarily due to changes in pressure drag.
Which car experiences the highest aerodynamic drag in the HTS maglev train?
The tail car experiences the largest aerodynamic drag, while the head car experiences the smallest.
How does the U-shaped track affect the flow around the HTS maglev train?
The U-shaped track significantly constrains the flow around the train body, forming strong vortex structures that influence aerodynamic performance.
What turbulence model was used in the simulation of the HTS maglev train?
The improved delayed detached eddy simulation (IDDES) turbulence model with the SST k-ω two-equation was used.
What is the design speed of the HTS maglev prototype developed by Southwest Jiaotong University?
The design speed of the high-speed HTS pinning maglev prototype is 620 km/h.
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