The energy transfer and conversion of exhaust gas flowing across junctions of exhaust manifold plays an important role in determining performance of turbocharging system. With the increase of engine boost pressure, exhaust gas velocity increases significantly, which increased compressibility of exhaust gas flow simultaneously. The existed exhaust T-junction models that do not take gas compressibility into consideration are not capable to simulate the exhaust gas flow with high boost pressure good enough. In order to predict pressure loss coefficients of high-pressure gas flow with higher accuracy, this paper developed a new T-junction models in which compressibility of gas flow was taken into consideration. A particle image velocimetry (PIV) test rig was established to provide data for investigating influences of flow parameters on the flow state and thermodynamic parameters in the T-junction. The results show that there are obvious streamline contractions in the internal flow field of the junction, and the formed boundary streamline divides the junction into two regions, as the flow ratio increases, the absolute value of the vorticity increases, and the vorticity in most areas of the branch joint is zero. In addition, the flow ratio of the branch pipe and the main pipe and the Mach number of the outflow affect the flow of the junction. Based on the results of the PIV test, a new pressure loss coefficient T-junction model for compressible flow is proposed. The new model has good prediction accuracy of the pressure loss coefficient and the prediction accuracy of the exhaust pressure wave increases by 4.43% when the pressure coefficient model is used in one-dimensional simulation program.

流经排气歧管连接处的废气的能量传递和转换在决定涡轮增压系统的性能方面起着重要作用。随着发动机增压压力的增加，排气速度显着增加，同时增加了排气流的可压缩性。现有的未考虑气体压缩性的排气T型接头模型无法很好地模拟高增压压力下的排气流动。为了更准确地预测高压气流的压力损失系数，本文开发了一种新的T型接头模型，其中考虑了气流的可压缩性。建立了粒子图像测速 (PIV) 试验台，为研究流动参数对 T 型接头中流动状态和热力学参数的影响提供数据。结果表明，结点内部流场存在明显的流线收缩，形成的边界流线将结点分为两个区域，随着流量比的增加，涡度绝对值增大，大部分区域的涡度变大。分支关节的数量为零。此外，支管与主管的流量比和流出的马赫数都会影响接头的流量。基于PIV试验的结果，提出了一种新的可压缩流压力损失系数T型接头模型。