# Simulation and Experimental Research on the Energy Loss of Confluence Pipelines
## 1 Introduction
Based on the numerical simulation results of Fluent, the energy loss and fluid flow characteristics in the confluence area of a 35\({}^{\circ}\) bifurcation pipe were predicted. [PERSON] [16] numerically evaluated different injection configurations for the analysis of two-phase flow behavior and evolution through a staggered Y-junction pipeline. [PERSON] [17] investigated the shape and hydrodynamic characteristics of the sand bed at the junction of urban pipelines and their relationship with the flow ratio. [PERSON] [18] put forward suggestions for the optimization of hydraulic parameters for pipeline systems of hydropower stations with super-long headrace tunnels (HSSLHTs) based on the Mayfly algorithm and considering different operational scenarios. According to previous studies, the experimental study of curvature radius and pipe diameter on the energy loss coefficient is lacking. The influence of these parameters on energy loss can provide a scientific basis for optimizing the design of the bus pipe and improve the efficiency of the fluid conveying system. [PERSON] and [PERSON] [19] conducted an experimental study on the energy loss of T-shaped and Y-shaped confluence pipes. They used main and branch pipes with different angles and diameters to conduct experimental research. They explained that the negative energy loss coefficient found was due to the ejection effect of the main pipe when the velocity of the branch pipe was small. When the fluid velocity in the straight pipe is high enough, the fluid in the main pipe will be ejected, and the resistance coefficient of the main pipe will be negative. [PERSON] and [PERSON] [20] conducted an experimental study on a T-shaped confluence pipe made of cast iron. They conducted an experimental study on the different split ratios of a 90\({}^{\circ}\) T-shaped confluence pipe and fitted the curve of the experimental results; [PERSON] and [PERSON] [21] summarized the experience and theory of their predecessors and carried out theoretical and experimental research on three-way pipes with different structures. Their theoretical calculations are in good agreement with the experimental measurement results. [PERSON] [1] conducted experimental research on a T-shaped confluence pipe with a rounded inner wall. Their research results showed that the energy loss of the rounded T-shaped confluence pipe was reduced by 10-20%. [PERSON] [22] conducted hydraulic model experiments and numerical calculations of water flow characteristics, such as flow regime and head loss under different operating conditions, on the T-shaped bifurcation pipe in the Wuxi Mashan Pumped Storage Power Station. [PERSON] [23] conducted numerical simulation research on a 90\({}^{\circ}\) bend pipe with a large curvature radius using the RNG turbulence model and Fluent fluid dynamics simulation software. [PERSON] et al. [24] performed a numerical simulation of a 90\({}^{\circ}\) T-shaped manifold by using the standard two-way equation model using Fluent software. Focusing on the influence of turbulent viscosity, the temperature stress distribution and velocity gradient of the three-dimensional turbulent flow inside the pipeline were analyzed, and the flow field distribution inside the pipe was determined. [PERSON] [25] studied the numerical model of tee pipes with different cross-sectional area ratios for the main and branch pipes by applying the standard two-path turbulent flow model through Fluent and determined the flow field distribution inside the pipes. [PERSON] [26] used Fluent numerical simulation software to simulate the fluid flow of a T-shaped confluence pipe. The flow field characteristics of different structures such as a straight pipe, elbow pipe, and sudden expansion pipe were analyzed in the case of laminar flow and turbulent flow, and their energy loss variation law was obtained. [PERSON] [27] developed a physically guided neural network model to predict the temperature and pressure drop of oil pipelines.