有压输水管道内泥沙淤积形态及水力特性研究

Study on sediment deposition morphology and hydraulic characteristics in pressurized pipelines

为探究有压管道中泥沙淤积特性和泥沙的引入对管道水力参数的影响,以盐环定扬黄输水工程管道为例,采用物理模型观测与数值模拟相结合的方法开展研究。结果表明:模拟所用数学模型在计算结果上与物理模型试验观测数据及理论计算值基本一致,具有良好的适宜性;管道上升段底部泥沙在大流量下呈集中堆积分布,小流量下呈间断式分布,管道下降段底部泥沙在小流量、小坡度时出现间断分布特征,流量和坡度增大后呈带状分布;泥沙通过上升段之前,下降段小坡度泥沙淤积量与流量成反比,下降段大坡度和水平段泥沙淤积量与流量成正比;管道中泥沙的临界不淤流速与泥沙粒径成正比;管道上下游水位差在引入泥沙后增大,幅度在0.43~2.27 cm之间;管道断面流速在引入泥沙后略微减小,最大减小0.045 m/s,且泥沙进入管道会使断面峰值流速上移;各断面压强在清水和水沙条件下基本不变,最大仅相差0.46%。

To explore the sediment deposition characteristics in pressurized pipelines and impacts of sediment introduction on the hydraulic characteristics,a pipeline model based on Yanhuanding water transmission project was taken as an example,and the numerical simulation method was adopted in combination with experimental observation.The results showed that the mathematical model used in the simulation was basically consistent with the experimental observation data and theoretical calculation values,and has good suitability.The sediment at the bottom of the pipeline rising section was distributed in a concentrated accumulation pattern under high flow rates,and in an intermittent pattern under low flow rates.While the sediment at the bottom of the descending section exhibited intermittent distribution characteristics when the flow rate and slope were small,and showed a band shaped distribution when the flow rate and slope increased.Before the sediment passed through the rising section,the sediment accumulation in the small slope of the descending section was inversely proportional to the flow rate,while the sediment accumulation in the steep slope and horizontal section of the descending section was directly proportional to the flow rate.The critical non-silting velocity of sediment in the pipeline was proportional to the particle size of the sediment.The water level difference between the upstream and downstream of the pipeline increased after the introduction of sediment,and the range was between 0.43~2.27 cm.After the introduction of sediment,the velocity of pipeline section decreased slightly,with a maximum decrease of 0.045 m/s,and the peak velocity in a pipeline section shifted upward when sediment was mixed.The pressure at each section remained basically unchanged under clear water and water sand conditions,with a maximum difference of only 0.46%.