三通管是管网系统中一种常用的管道连接件，主要用于改变管内气流流动方向及各出口处流量，被广泛应用在航空航天、石油化工等行业中。当管内气流流经三通管分叉处时，由于流道截面发生较大变化，管内流场发生变化，有可能加剧气流湍流强度，严重时发生流动分离等非定常流动现象，导致气流脉动压力增大，在管内空腔诱发产生剧烈噪声。同时，当气流的脉动压力与三通管结构模态频率接近时，容易引起管道共振，严重时将导致三通管管道破裂。因此，开展三通管流场、声场及结构特性研究具有重要工程应用价值。本文主要通过数值计算和试验的研究方法对三通管的流场、声场及结构开展了以下主要工作：

（1）基于相似理论设计了三通管气动模化试验，研究了三通管在三种流量工况下气流脉动压力特性，并比较了导流装置对三通管气流脉动压力特性的影响。结果表明，无导流装置时，三通管分叉处气流稳定性较差，容易导致三通管两支管间气流存在脉动能量分布不平衡现象。沿着气流流动方向，脉动能量分布不平衡性逐渐减弱。安装导流装置后，两出口管间气流脉动压力标准差相对大小减少了约11%~22%，使得三通管支管间脉动能量分布不平衡性得到改善。此外，导流装置还可以降低三通管分叉处附近气流约38%~50%的脉动压力强度，其脉动压力功率谱能量减少约66%~88%。而对于导流装置出口下游处气流脉动强度大的一侧支管，其气流脉动压力强度降低约16%~51%。导流装置有利于改善管道出口上游处气流流动稳定性，从而提高气流流动均匀性。

（2）基于四传声器传递函数法设计了三通管声学试验，并基于声学试验台管路进行声学数值计算，研究了导流装置对三通管管内声音传播的影响，其中数值计算结果与声学试验结果变化趋势基本一致，表明数值计算方案可靠。结果表明，导流装置能有效减少管内270 Hz、287 Hz、375 Hz和440 Hz频率附近的噪声，对2500 Hz~4500 Hz宽频范围内噪声最大可减少约18 dB。同时，由于三通管结构的对称性，三通管的中间管路处噪声总是以相同能量分别向两个支管传播。

（3）借助ANSYS软件对三通管管路进行了模态分析。数值计算结果表明，三通管结构的前十阶的固有频率在120 Hz~165 Hz频率范围内，可通过减少该频率激励力强度和对该位置管道增加约束以提高管路刚性，从而减少管路发生共振而导致管道破裂。

相关研究有助于加深对三通管内部流动、声场及结构特性的认识，为三通管的深入研究奠定了基础。同时，导流装置丰富了三通管优化流场及声场的技术手段，具有一定的工程参考价值。

In the pipe network system, the tee pipe is a commonly used as the pipe joint, which can be used to change the flow direction and the flow rate of the airflow at each outlet. Also, it’s widely used in aerospace, petrochemical and other industries. When the airflow flows through the bifurcation of the tee pipe, the flow field would be changed greatly due to the large change in the cross section of the flow channel, resulting in the increase of intensity of turbulence, even the unsteady flow phenomena, such as flow separation and the increase of pressure fluctuation. What’s more, the pressure fluctuation itself may induce severe noise in the cavity of the pipe. In the meantime, it’s more likely to occur the phenomena of resonance between the structure and the airflow when the frequency of pressure fluctuation is close to the modal frequency of structure, causing the occurrence of broken structure. Therefore, research was carried out in the aspect of flow field, noise and structure by means of experiment and numerical calculation.

Firstly, the aerodynamic modeling experiments are carried out to investigate the characteristic of airflow pressure fluctuation under three different flow rates based on similarity theory and the differences of pressure fluctuation are then com Pared whether the guide device is mounted or not. It turns out that when the guide isn’t installed, the stability of airflow in bifurcation of the tee pipe is weak, which may easily lead to imbalanced distribution of pressure fluctuation between the two branches of the tee pipe. But along with the direction of airflow, the phenomena of imbalanced distribution gradually become weaker. However, compared with situation that the guide device isn’t installed, the guide device will greatly enhance the stabilities of upstream of airflow. As a result, the relative size of the standard deviation of pressure fluctuation between the two branches drops nearly 11%~22%, resulting in the improvement of imbalanced distribution of the pressure fluctuation between the two branches. Moreover, the standard deviation and the power spectrum of airflow pressure fluctuations at pipe bifurcation junction are reduced practically 38%~58% and 66%~88%, respectively. As for the one branch in the downstream with high airflow pressure fluctuation, the guide device helps reduce 16%~51% of airflow pressure fluctuation. In a word, the results shows that the guide device can significantly serve the purpose of stability of airflow at the upstream of the pipe as well as the enhancement of uniformity of the airflow.

Secondly, based on the four-microphone transfer function method, the acoustical experiment is carried out to study the effect of guide device while the numerical calculation is also designed in the same condition. Compared with the experimental results, the results of calculation prove to reliable. As the results reveal, the sound in about 270 Hz, 287 Hz, 375 Hz and 440 Hz, can be effectively reduced owing to the guide device. Moreover, the sound in the wide frequency range of 2500 Hz~4500 Hz drops almost 18 db. Meanwhile, the sound from the inlet of the pipe always propagate to the two branches of the pipes with the same energy since it’s a symmetric tee pipe.

Lastly, with the help of the ANSYS Mechanics, the modal analysis of the tee pipe is investigated. It turns out that the range of the natural frequencies of the pipeline is nearly 120 Hz~165 Hz. Therefore, in order to prevent the resonance of the tee pipe which may cause the pipeline rupture, some measures can be done like reducing the strength of excitation among these frequencies or increasing the restriction of the pipeline at those locations.

The research helps to get better understanding of the characteristic of flow field, noise and structure of tee pipe, laying the foundation of the further research. Meanwhile, the guide device enriches the technical way of optimizing the flow field and sound field of the tee pipe, which has the engineering reference value.