中文摘要：

运用Fluent软件中的大涡模型对90°弯管中的非定常湍流场进行了数值模拟,在流场计算的基础之上,采用FW-H方程研究声场行为,得到5个不同截面的声压随时间变化关系图.从模拟结果可知,流场在一定的外界条件下会产生二次涡,这些涡与涡之间的相互融合或分裂产生了一定的声压.进一步给出5个不同截面流场和声场的变化情况,以及不同时刻涡和涡之间的相互作用对声场的影响.针对流场的5个特定区域,在其截面上选取5个监测点,利用FW-H方程进行计算,结果发现声场中声压随时间的增加先达到极大值后迅速趋于平稳.

英文摘要：

The unsteady turbulent flow field for 90°bend tube was numerically simulated by using the large eddy model of the fluent software.On the basis of the flow field calculation,the sound field was monitored by FW-H equation,getting five diagrams which showed the relationship that the sound pressure of different cross section changed with time.The simulation results showed that the flow field can produce secondary vortex in a certain external conditions.The merge or split between the vortex and the vortex produced a certain sound pressure.The changing situation of flow field and sound field on the five different cross sections were also showed,The interaction between vortexes in different moments influence on the sound field was confirmed.According to the five specific areas of the flow field,five monitoring points were selected on the each cross sec-tion,and then they were simulated on by FW-H calculation.The results showed that,the sound pressure in the sound field increased with time firstly,and quickly leveled off after reaching the maximum value.