动车组司机室空调蒸发器气动噪声数值仿真

Numerical simulation on aerodynamic noise of air conditioning evaporator of EMU cab

为研究动车组司机室空调蒸发器的噪声响应,建立某型司机室分体式空调蒸发器的计算流体动力学模型,采用FLUENT中的大涡模拟(large eddy simulation,LES)计算瞬态气动流场。对瞬态流场数据进行傅里叶变换,得到空气流场的频域数据。基于流场频域数据,采用Virtual.Lab的边界元法计算蒸发器的气动噪声,采用声压法计算蒸发器的辐射声功率,并与测试结果进行对比分析。结果表明:蒸发器出口位置气动噪声最高,最大声压级高于56 dB;最大声功率级出现在125~400 Hz的低频段;声功率级随着频率的增加逐渐降低,但在5000 Hz的高频辐射中声功率级仍然超过55 dB,这表明空调蒸发器气动噪声属于宽频噪声;计算结果与测试结果吻合良好,验证声压法计算空调蒸发器气动声功率可行。

To study the noise response of air conditioning evaporator in EMU cab,the computational fluid dynamics model for evaporator of a split air conditioning in the cab is established.The large eddy simulation(LES)of FLUENT is used to calculate the transient aerodynamic flow field.The frequency domain data of air flow field is obtained by Fourier transform of transient flow field data.Based on the frequency domain data of flow field,the aerodynamic noise of evaporator is calculated using boundary element method of Virtual.Lab,and the radiated sound power of evaporator is calculated by sound pressure method.The calculation result is compared with the test result.The results show that the aerodynamic noise at the outlet of evaporator is the highest,and the maximum sound pressure level is higher than 56 dB;the maximum sound power level appears in the low frequency band of 125~400 Hz.The sound power level decreases gradually with the increase of frequency,but the radiation sound power level of high frequency(5000 Hz)still more than 55 dB.It indicates that the aerodynamic noise of air conditioning evaporator belongs to broadband noise.The calculated results agree well with the measured ones,and the calculation of aeroacoustic power of air conditioning evaporator by sound pressure method is verified.