## 3 Results and Discussion
### Flow Characteristics in the Branch Outlet  
As shown in Figure 7, the maldistributions of \(\dot{m}_{\rm B}\) and \(x_{\rm B}\) in the branch outlets are rather significant. The liquid mass flow rate in each branch outlet (\(\dot{m}_{\rm L,B}\)) increases with the increasing of \(\dot{m}_{\rm in}\). Moreover, the liquid flows into the header and jets on the header wall of the header. A part of the liquid breaks up into droplets that are thereafter dragged into the branch outlets by the vapor, which is termed as \"droplet entrainment\". A similar phenomenon was also found by [PERSON] [12] and [PERSON] [20]. Obviously, \(\dot{m}_{\rm L,B}\) in \(B_{3}\) is remarkably higher than that in \(B_{1}\) and \(B_{2}\). This is because the liquid flows to \(B_{3}\) is not only by droplet entrainment, but also comes from the overflowing liquid from the orifice-baffle that cannot be drained promptly. However, the vapor in the branch outlet is more uniform than liquid owing to its lower inertia force. \(\dot{m}_{\rm V,B}\) in \(B_{1}\) is slightly lower than \(B_{2}\) and \(B_{3}\) for the considered \(\dot{m}_{\rm in}\).  
The droplets which enter the branch outlet is mostly due to the drag of the vapor. Hence, the vapor velocity is essential. To further explore the vapor flow characteristic, the vapor velocity distribution along each branch outlet and the specific header planes are plotted in Figure 8. The two-phase fluid flows from the branch inlet \(I_{4}\) and mixes in \(S_{10}\). Due to the inertia, the fluid gathers on the right side of the header and a vortex is generated on the left side, resulting in the vapor velocity on the left side being lower than that on the  
Figure 6: (**a**) Instructions and distributions of velocity and density in each orifice at (**b**) 9 g/s, (**c**) 12 g/s, (**d**) 15 g/s, (**e**) 18 g/s and (**f**) 21 g/s.  
Figure 7: Mass flow rate in each branch outlet.  
right side. After \(S_{10}\), the fluid continues to flow downwardly, and then a part of it is divided into the \(B_{1}\) because of the suction of the branch outlet. The fluid is more accumulated at the lower part of \(B_{1}\) due to the inertia (\(S_{7}\)), in which the vortex exists above the \(B_{1}\) and shows a vapor velocity non-uniform distribution. The other part of the fluid from \(I_{4}\) that cannot enter \(B_{1}\) in time will keep flowing in the header. In this way, the fluid also flows on the left side, resulting in a lower non-uniformity at \(S_{11}\). Similarly, the vapor velocity distribution in the next branch outlet (\(S_{8}\)) and header (\(S_{12}\)) are close to the \(S_{7}\) and \(S_{11}\) respectively. However, due to the diversion of the fluid, the vapor velocity decreases correspondingly. On the other hand, in the \(B_{3}\), the distribution of the vapor velocity is more uniform. This is mainly due to the fact that \(B_{3}\) has a maximum mass flow rate than \(B_{1}\) and \(B_{2}\), in which case the fluid can be fully fill at the \(B_{3}\), where there is no vortex generated. With the increase in \(\dot{m}_{\text{in}}\), not only does the velocity increase but it also improves the non-uniformity of the velocity distributions.