突扩圆管局部水头损失实验教学的改进

Improvement of local head loss experiment within sudden expansion pipe in hydraulics teaching

突扩圆管局部水头损失量测实验是水力学实验教学的重要内容之一,对其实验内容进行深化,进而推进水力学实验教学的创新。从突扩圆管水流流动的能量方程出发,导出了流动雷诺数影响下的局部水头损失系数的计算公式,并依据圆管紊流指数律的流速分布假设,分析了在低雷诺数情况下局部水头损失系数随雷诺数的变化规律,实验数据验证了局部损失系数计算公式的合理性和可靠性。

The calibration experiment of local head loss within sudden expansion pipe is one of the important contents in hydraulics experiment.It will advance the innovation of hydraulics experimental teaching by deepening the calibration experiment of local head loss within sudden expansion pipe.Based on energy equation for water flow in sudden expansion pipe,the formula of local loss coefficient with consideration of flow Reynolds number is deduced.According to the hypothesis of exponential turbulent velocity distribution in circular tube,the variation law of the local loss coefficient with Reynolds number under low Reynolds number is analyzed.Rationality and reliability of the formula of the local loss coefficient are tested by experimental data.