Experiment and calculation of deposition velocity of suspended particles in storm drainage

Deposition particles can lead to blockage, odor, and corrosion of pipes, and the deposition process of suspended particles is particularly complicated. In order to quantify the deposition process of suspended particles and mastered the critical conditions for the deposition in storm drainage, the process was simulated experimentally, and the deposition states of suspended particles under the different roughness of pipe wall, particle size, and density were analyzed. Two mathematical models of deposition critical velocity and easy deposition velocity were established. Results showed that with the increase of particle size and density, the gravity of particles increased and deposition was more likely to occur. In the rough pipeline, the kinetic energy consumption of water flow increased, the ability to carry particles was weakened, and the deposition rate would increase accordingly. The higher the flow velocity, the lower the deposition rate. The deposition states of particles in the pipeline could be divided into three types according to the deposition rates: "no deposition," "minor deposition," and "bulk deposition." Verification showed that the difference rates between the calculated values and measured values of the deposition critical velocity ranged from - 3.23 to 2.86%, and the difference rates of the easy deposition velocity were - 4.14-4.72%, showing good consistency.