森林消防远程供水系统聚氨酯水带水力特性研究

Hydraulic characteristics research on polyurethane hose used in forest firefighting remote water supply system

森林消防远程供水系统是森林火灾扑救的重要技术手段,为研究系统输水效果,对聚氨酯水带的水力特性开展了理论分析和试验研究。结果表明:聚氨酯水带沿程摩阻损失同雷诺数Re和管壁粗糙度?有关。其流动一般处于紊流区,在光滑管紊流区,摩阻系数λ只与Re有关;在混合摩擦区,λ与Re和?均有关;在粗糙管紊流区,λ只与?有关。同等流量下,管径越小,Re越大,摩阻损失越大,流态进入下一区间的时间越早。同一段管道,粗糙度越低,λ越小;粗糙度降低一个数量级,水力损失降低40%左右,可以极大提升输水效率。通过试验测得系统选用的DN100单层聚氨酯水带的绝对当量粗糙度约为0.3 mm,并以此计算出10 km远程供水系统的管路特性曲线,同试验结果基本一致,验证了供水系统在设计流量下工作的科学性。

The remote water supply system for forest fire fighting is an important technical means for forest fire fighting.In order to study the water conveying effect of the system,theoretical analysis and experimental research on the hydraulic characteristics of polyurethane hose were carried out.The results show that the frictional resistance loss of polyurethane hose along the pipeline is related to Reynolds number(Re)and wall roughness(Δ).Its flow is generally in the turbulent region.In the smooth pipe turbulent region,the frictional coefficientλis only related to Re.In the mixed friction region,λis related to both Re andΔ.In the rough pipe turbulent region,λis only related toΔ.Under the same flow rate,the smaller the diameter,the larger the Re,and the greater the frictional resistance loss,and the earlier the flow state enters the next interval.For the same section of pipeline,the lower the roughness,the smaller theλ,and when the roughness decreases by one order of magnitude,the hydraulic loss decreases by about 40%,which can greatly improve the water conveying efficiency.Through experiments,it is measured that the absolute equivalent roughness of the single-layer DN100 polyurethane hose selected by the system is about 0.3 mm.The pipeline characteristic curve of the 10 km remote water supply system is calculated based on this,which is basically consistent with the experimental results,verifying the scientific nature of the water supply system working under the design flow rate.