真空管道磁浮交通车体热压载荷分布特征及其非定常特性

Distribution and unsteady characteristics of the temperature and pressure loads acting on the car-body in evacuated tube maglev transport

基于SST κ-ω湍流模型和IDDES方法,采用三维数值模型对800 km/h的真空管道磁浮交通系统在雍塞状态(阻塞比为0.3和0.2)和非雍塞状态(阻塞比为0.1)下进行瞬态模拟,得到列车车体热压载荷时均分布特征及其波动特性,并利用跨声速风洞凸块试验数据验证了数值方法的准确性。基于本征正交分解提取流场重要相干结构,识别列车表面载荷非定常较强区域,揭示其时空演化规律。研究结果表明:列车上表面载荷分布特征与拉瓦尔喷管相似,雍塞/非雍塞状态下载荷分布差异主要位于扩张段;列车下表面载荷分布因悬浮架腔体的截面突变而变得复杂,气流突入到第一个悬浮架腔体形成局部滞止点,造成车体压力大幅度振荡,同时热量在列车底部聚集,尾车下洗气流和上洗气流相互作用差异导致了雍塞/非雍塞状态下温度峰值的位置不同;列车表面压力非定常较强区域主要位于底部悬浮架处,且存在14 Hz的特征频率,雍塞状态下尾车激波处也是一个非定常源;中间车、尾车温度载荷一阶模态体现了热量累积过程。

Based on the SST κ-ω turbulence model and the IDDES method,a three-dimensional numerical model was used to simulate the transient state of an evacuated tube maglev transport system at 800 km/h in the choked(blockage ratio of 0.3 and 0.2)and unchoked(blockage ratio of 0.1)states.The accuracy of the numerical method was verified using transonic wind tunnel bump test data.Additionally,the significant coherent structure of the flow field was extracted based on the proper orthogonal decomposition,the region with the strong unsteady load on the train surface was identified,and its space-time evolution law was revealed.The results show that the load distribution on the upper surface of the train is similar to that of the Laval nozzle,and the difference in load distribution between the chocked/unchoked conditions is mainly in the divergent section.The load distribution on the lower surface of the train becomes complex due to the abrupt change in the cross-section of the bogie cavity.The difference in the interaction between the upwash and downwash flow leads to different locations of the temperature peaks under the choked/unchoked conditions.The strong unsteady pressure region on the train surface is mainly located at the bottom bogie and has a characteristic frequency of 14 Hz.The tail car shock wave is also an unsteady source under choked conditions.The first-order modes of the middle and tail car temperature loads reflect the heat accumulation process.