# Experimental Study on Horizontal Pipeline Transportation Characteristics of Coarse Particle
## 3 Experimental Preparation  
### Experiment Setup  
The experimental material is a slurry consisting of three different grain sizes of quartz sand and water, and its physical properties are similar to those of dredged material. The density of the quartz sand was 2650 kg/m\({}^{3}\), and the average grain size was 0.9, 1.5, and 2.5 mm, respectively. Figure 7: Schematic diagram for calculating the cross-sectional area of the granular layer in the pipe. The main equipment for the experiments were circulation pipes, power equipment, data monitoring equipment, and filming equipment. As shown in Figure 8, this experiment included a circulating pipeline system that simulates sediment pipeline transportation. The system is mainly divided into a circulating water tank, an initial development section (AB), a fully developed section (BC), a horizontal observation section (CD), a vertical observation section (EF), an inclined observation section (GH), a reflux section (IJ), and an outlet section (JK). The pipeline circulation system is provided with the kinetic energy required for the movement inside the pipeline by the sediment pump. After the sediment pump is started, the mixture of sediment and water in the sediment tank enters the initial development stage AB; after a certain distance of flow development, it enters the fully developed stage (BC), at which point the water phase in the pipeline reached laminar flow state. Subsequently, it enters the horizontal observation section (CD), vertical observation section (EF), and inclined observation section (GH) in sequence, which can be used to physically observe the movement state of sediment particles inside the pipe. Finally, it enters the reflux section (IK) and the outlet section (JK) to return to the mud and sand tank, completing the circulation of the entire circulation pipeline system. As shown in Figure 8, the main structural dimensions of the circulating pipeline system are a total length of 24.6 m, an initial development section + outlet section (AB + JK) with a total length of 3.5 + 5.5 = 9 m, a fully developed section (BC) with a length of 1.8 m, a horizontal observation section (CD) with a length of 3.1 m, a vertical observation section (EF) with a length of 1.6 m, an inclined observation section (GH) with a length of 1.8 m, a reflux section (IJ) with a length of 3.5 m, and other bent pipe sections with a total length of 2.4 m.  
Among them, the pipes are all made of transparent polymer polyvinyl chloride (PVC) material with an inner diameter of 45 mm, which has the advantages of easy observation and high strength. The power equipment used in this experiment is a variable frequency-controlled sediment pump, and the mixing device is a skewed blade slurry mixer. The specifications of the sediment pump are flow rate of 40 m\({}^{3}\)/h, head of 12 m, power of 4 kW, and speed of 1480 r/min. The three-phase motor model matched with the sediment pump is G-112B, power of 80 W, speed of 2550 r/min, and air volume of 229 m\({}^{3}\)/h. The mixer used is the BLD-10 mixer produced by Jiangsu Yingma Transmission Equipment Co., Ltd. (Changzhou, China). Its specifications are mixer power of 0.75 kW, speed of 850 rpm, mixing rod length of 600 mm, impeller diameter of 300 mm, and double-bladed wheel mixing. Figure 8: Schematic diagram of pipeline hydraulic transportation experimental system. The monitoring parameters of this experiment include pipeline pressure, flow rate, concentration, etc. Pressure sensor using xingyi Sensor Manufacturing Co., Ltd. (langfang, China).production CYZ51A-H-12-A1-14-B-G flat membrane pressure transmitter, used to monitor the real-time pressure value of the pipeline. The specifications of the pressure transmitter are range of 0-1 MPa, output of 4-20 mA, and connection of M20\(\times\)1.5. Accuracy level is 0.25; power supply is 9-36 VDC. The electromagnetic flowmeter is a KEFT-type electromagnetic flowmeter produced by Shanghai Kent Instrument Co., Ltd. (Shanghai, China).