Numerical Simulation of Water–Sediment Characteristics in a Trapezoidal Desilting Channel with a Swirling Flow Generator

Desilting channels with a swirling flow generator (DCSFG) are a new water–sediment separation technology. Water–sediment characteristics are crucial for its popularization and application, but research on trapezoidal desilting channels with a swirling flow generator (TDCSFGs) is insufficient. Based on model tests, this paper studies the suitability of mathematical model of water–sediment characteristics of TDCSFGs by numerical simulation and analyzes the hydraulic characteristics and sediment discharge behavior of TDCSFGs under the condition of continuous sediment inflow. The results showed that the numerical simulation results are close to the model results, the maximum relative error is less than 5%, and the average absolute error and root-mean square error are close and in a reasonable range, which shows that the mathematical model is stable and accurate in predicting water and sediment properties. Under the continuous strip condition, when the incoming flow rate is 215 m3/h, the sediment trapping efficiency with particle size range of (0.075, 3.0000) mm and median particle size of 0.600 mm is 73.31%, and the water abstraction ratio is only 5.37%. When the inflow rate is 215 m3/h, the sediment with the particle size range of (1.250, 3.000] mm can be completely discharged, and the sediment trapping efficiency for sediment with the particle size range of (0.600, 1.250] and (0.315, 0.600] mm is 98.32% and 76.87%, respectively. Due to the influence of the channel inflow conditions, the sediment trapping efficiency of TDCSFGs for the sediment with the particle size range of (0.075, 0.160] mm is only 14.71%, indicating that the TDCSFGs can basically discharge the bed-load sediment and some suspended-load sediment in the channel, and it has favorable sediment discharge performance. The results have certain engineering application value and can provide reference for the application of TDCSFGs in practical engineering.