Numerical study on the flow field characteristics of the new high-speed maglev train in open air

Abstract

With the increasing demand of higher travelling speed, a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h. To better capture the flow field structures around the maglev train, an improved delayed detached eddy simulation (IDDES) is adopted to model the turbulence. Results show that the new maglev train has good aerodynamic load performance such as small drag coefficient contributing to energy conservation. The main frequencies of aerodynamic forces for each car have a scattered distribution. There are two pairs of counter-rotating large vortices in the non-streamlined part of the train that make the boundary layer thicker. Many high-intensity vortices are distributed in the narrow space between skirt plates or train floor and track. In the gap between the train floor and track (except near the tail car nose), the main frequency of vortex shedding remains constant and its strength increases exponentially in the streamwise direction. In the wake, the counter-rotating vortices gradually expand and reproduce some small vortices that move downward. The vortex has quite random and complex frequencydomain distribution characteristics in the wake. The maximum time-averaged velocity of the slipstream occurs near the nose of the head car, based on which, the track-side safety domain is divided.

目的

通过对新型高速磁浮车的绕流进行数值模拟,研 究气动荷载、涡流及滑流的分布规律,为常导高 速磁浮车的研发和应用奠定一定的气动基础。

创新点:1. 将可压缩流动理论及延时分离涡(IDDES)方 法应用于高速磁浮车气动问题;2. 通过数值模 拟,首次揭示高速磁浮车诱发的涡流特性。

方法:1. 基于430 km/h 的磁浮车气动试验数据,验证本 文数值方法的可靠性,并建立三编组新型高速磁 浮车的计算模型;2. 采用IDDES 方法对关键问题 即湍流求解进行建模,以捕捉较为精细的流场结 构;3. 采用时均化和快速傅里叶变换等方法对流 场数据进行后处理,以研究流场的时均和频率等 特性。

结论:1. 新型高速磁浮车具有良好的气动性能,比如较 小的阻力系数、合理的升力系数和分散性较好的 气动力主频分布。2. 在非流线型车身附近,两对 反向旋转的大涡使得边界层明显增厚。3. 高强度 的涡流主要分布在裙板与轨道以及轨道与车底 之间的狭小空间;在轨道与车底之间(除了靠近 尾车鼻尖附近的区域),涡脱频域几乎不变,且 涡强沿流向指数式增大。4. 伴随着涡流的分裂及 衍生,尾流具有复杂的、随机的频域分布特性。

5. 高速磁浮车产生的时均滑流具有5 个典型的变 化过程。