高速双层动车由于其内部空间紧凑以及元件的高功率化,冷却系统存在整体散热性能较差、噪声污染严重的问题.为此,通过冷却系统空气流场的数值模拟与试验研究,对其散热性能和噪声控制进行了优化.参照常用的冷却系统空气流道结构,基于双层动车复合式冷却系统的技术参数要求,对其尺寸进行了初步设计计算.分别采用多孔介质模型和多参考系(MRF)对复合式冷却系统换热器的芯体结构与旋风过滤器进行简化,并对其空气侧流场进行数值模拟.研究结果表明:风机入口处存在局部涡流,导致流体进入通风机的角度混乱,影响风机有效做功,在工作环境下系统风量(2.96 m3/s)远小于设计值(3.35 m3/s);同时局部涡流产生较大的气动噪声.此外,换热器入口的风速分布不均匀,导致系统冷却能力不足.针对上述问题,对空气流道结构进行了优化.调整了进、出口消声器的3个流道的流通面积,并在过渡段设置"喇叭型"导流结构来改善换热器进口处风速的均匀性;在冷却系统进、出口增加弧线型消声器能进一步降低噪声.结果表明:空气流道结构优化后水侧散热功率从33.18 kW增加到41.55 kW,油侧散热功率从157.82 kW增加到173.82 kW,系统加权平均噪声值从74.95 dB(A)降低到72.21 dB(A).本研究可为类似工程项目冷却系统的优化设计提供参考,有助于改善乘坐体验和车辆运行的经济性.
High-speed double-decker EMU has the problems of poor overall heat dissipation performance and serious noise pollution in the cooling system due to its compact internal space and high power of components.For this reason,the heat dissipation performance and noise control were optimized by numerical simulations and experimental study of the airflow field of the cooling system.By referring to the general air channel structure of the cooling system and the technical parameter requirements of the combined cooling system for double-deck EMU,its structure and size were preliminary calculated and designed.The structure of the heat exchanger and cyclone filter in the combined cooling system was simplified using a porous medium model and a multiple reference frame(MRF),respectively,and the airflow field was numerically simulated.The research results indicated that a local vortex at the fan's inlet would lead to a chaotic flow of air entering the fan and affect the effective work of the fan.The air volume flux of the system(2.96 m3/s)in the working environment was much lower than its design value(3.35 m3/s).Meanwhile,local vortices brought serious aerodynamic noise.In addition,the uneven distribution of air velocity at the inlet of the heat exchanger resulted in insufficient cooling capacity of the system.The air channel structure has been optimized to avoid the above issues.The flow area of three air channels at the inlet and outlet of the silencers were all adjusted.A diversion structure with a horn shape was installed in the transition section to improve the uniformity of air velocity in front of the heat exchanger.The arc-shaped silencers were fixed at the inlet and outlet of the cooling system to further reduce the noise.Results showed that the heat dissipation power from the water increased from 33.18 kW to 41.55 kW,the heat dissipation power of oil increased from 157.82 kW to 173.82 kW,and the weighted average noise value of the system decreased from 74.95 dB(A)to 72.21 dB(A)after optimizing the air channel structure.This study can guide the optimization design of cooling systems in similar engineering projects and is helpful to improve the ride feel and the economy of vehicle operation.