# Simulation and Experimental Research on the Energy Loss of Confluence Pipelines
## 3 Experimental System for the Energy Loss of the Arc Confluence Pipeline  
The experimental system required to determine the energy loss of the arc confluence pipeline was built with reference to the experimental device designed by [PERSON] and [PERSON], which was originally designed to measure the energy loss of a T-shaped confluence pipeline. The experiment was carried out at room temperature (20 \({}^{\circ}\)C) with water as the fluid medium. The experimental system primarily includes three parts: the flow measurement system of the arc confluence pipeline, the pressure measurement system of the arc confluence pipeline, and the arc confluence pipeline specimen. In this energy loss experiment on an arc confluence pipeline, such pipelines with different curvature radii and different materials were tested under different flow rates with water as the medium, and the energy loss of the arc confluence pipelines was measured using the local energy loss measurement system of this type of pipeline. The system is supplied with water by a submersible pump, and ball valve 2 is responsible for pressure limiting and diversion, as shown in Figure 6. The outlet of the water pump is divided into two paths, and each branch changes the flow of the two water inlets of the arc confluence pipeline by adjusting ball valves 10 (11) and 12 (13). Double valves in parallel are used to adjust the flow. When the flow is larger, the ball valve with a larger inner diameter is used to roughly adjust the flow, and when the flow is smaller, the ball valve with a smaller inner diameter is used to fine-tune the flow. The pressure of the two branch pipe inlets of the arc confluence pipeline is measured through intelligent pressure transmitters 4 and 8, and the flow of the two branch pipe inlets of the arc confluence pipeline is measured through intelligent electromagnetic flowmeters 3 and 9. For the energy loss experiment on the arc confluence pipeline, after determining the pipe diameter, curvature radius, material, and fluid medium of the pipeline, the fluid velocity in the pipe is proportional to Reynolds number Re. The fluid is in different flow states at different Reynolds numbers, resulting in different energy loss coefficients. The energy loss of the arc confluence pipeline not only includes local energy loss but also includes energy loss along the path according to the energy loss mechanism of the arc elbow due to its geometric structure characteristics. The authors assume that, with a fixed pipe diameter, when the radius of curvature is reduced to the same as the radius of the pipe section, it is close to the T-shape piped and its loss is local energy loss; when the radius of curvature increases infinitely, it is close to the straight pipe, and its energy loss is energy loss along the path; lastly, when the curvature radius is between the two, the energy loss is the sum of the energy loss along the path and the local energy loss. Figure 5: Comparison of the energy loss coefficient of confluence pipelines with different structures. The influence of curvature radius on the energy loss of the arc confluence pipeline was studied theoretically and experimentally by using polymethyl methacrylate. The curvature radius ranges from 30 mm to 400 mm, covering a variety of situations from sharp to gentle bends, which is conducive to studying the impact of curvature radius on energy loss. The pipe diameters were 12 mm, 15 mm, and 20 mm and the radius of curvature was 30 mm, 65 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, and 400 mm. The energy loss of the arc confluence pipeline with different curvature radii at the same Reynolds number was measured experimentally to determine the variation rule of the energy loss of the arc confluence pipeline changing with curvature radius. The choice of pipe diameters of 12 mm, 15 mm, and 20 mm is to cover pipes from smaller to medium sizes, which are relatively common in practical engineering applications and can represent a certain range of engineering issues.