高速列车气动及声学行为的尺度效应研究

Study on Scale Effect of Aerodynamic and Acoustic Behaviors of High-speed Trains

建立不同模型尺度的高速列车气动噪声数值计算模型,利用改进的延迟分离涡模拟方法(IDDES)和FW-H声学模型对高速列车近场流场和远场噪声进行数值模拟。通过风洞试验验证了本文数值计算方法的合理性。对比分析不同模型尺度下高速列车的气动力、流场结构、表面压力脉动以及远场噪声。结果表明:模型尺度对高速列车的气动行为和声学行为具有明显影响。随着模型尺度的减小,高速列车的气动阻力系数逐渐增大,模型尺度从1∶1减小到1∶8时,阻力系数增加11.3%。模型尺度对列车黏性阻力系数和尾车分离的尾流高度影响较大,但不改变列车表面压力分布规律和车体表面边界层的发展规律。列车表面压力具有明显的非定常性,随着模型尺度的减小,脉动压力的振荡程度减弱。模型尺度的变化未改变高速列车在远场纵向和横向上的传播特性,随着模型尺度的减小,对应噪声测点处的声压级逐渐减小。高速列车远场噪声没有明显的主频特性,能量分布在较宽的低中频率范围内,模型尺度不改变高速列车远场噪声的宽频特性。

The numerical calculation models of aerodynamic noise of high-speed trains with different model scales were established to numerically simulate the near-field flow field and far-field noise of high-speed trains using the improved delayed detached eddy simulation method(IDDES)and FW-H acoustic model.The rationality of the numerical calculation method in this paper was verified by wind tunnel test.The aerodynamic force,flow field structure,surface pressure pulsation and far-field noise of high-speed trains with different model scales were compared and analyzed.The results show that the model scale has a significant effect on the aerodynamic and acoustic behavior of high-speed trains.As the model scale decreases,the aerodynamic drag coefficient of high-speed trains gradually increases.With the decrease of the model scale from 1∶1 to 1∶8,the drag coefficient increases by 11.3%.The model scale has a great influence on the viscosity resistance coefficient of the train and the height of the wake separated by the tail car,but does not change the pressure distribution law on the train surface and the development of the boundary layer on the car body surface.Given the unsteadiness of the train surface pressure,the oscillation of pulsating pressure decreases with the decrease of model scale.The change of the model scale does not change the propagation characteristics of the high-speed train in the longitudinal and lateral directions of the far field.However,as the scale of the model decreases,the sound pressure level at the corresponding noise measurement points gradually decreases.The far-field noise of high-speed trains has no obvious main frequency characteristics,with the energy distributed in a wide low-medium frequency range.The model scale does not change the broadband characteristics of high-speed train far-field noise.