环境气压降低对挑射流水舌挑距影响的试验研究

水舌挑距是泄洪消能最基本参数之一,消能形态、冲击区域、冲坑深度、水流衔接均与其密切相关。为研究高海拔地区气压降低对挑射流特性的影响,采用减压模型试验的方法研究了环境气压对水舌挑距的影响程度。结果表明,气压与水舌挑距呈良好的线性关系,气压越低,因空气阻力越小,水舌挑距越远;气压每下降15kPa,对水舌内缘与外缘的最大影响程度分别为1.67%、1.48%;低气压环境下水舌空中扩散与掺气减弱,水舌厚度变薄,水流呈集中趋势。基于气压与空气阻力影响系数关系,修正规范水舌挑距计算公式,为高海拔地区挑射流设计提供参考。

Influence of Decrease of Environmental Pressure on Trajectory Distance of Jet

Trajectory distance of nappe is one of the most basic parameters of flood discharge and energy dissipation.The energy dissipation form,impact region,scour depth,and flow joint are closely related to the rajectory distance of nappe.To study the influence of pressure reduction on jet flow characteristics at high altitude,the vacuum model test method is used to study the influence of environmental pressure on the trajectory distance of jet.The results show that there is a good linear relationship between atmospheric pressure and the trajectory distance of jet,and the lower the atmospheric pressure is,the farther the trajectory distance of jet is,due to the smaller the air resistance.For every 15 kPa drop in atmospheric pressure,the maximum impact on the inner and outer edges of the jet nappe is 1.67%and 1.48%,respectively.The air diffusion and aeration of the jet nappe will be weakened under the low pressure environment,and the thickness of the jet nappe will be reduced and the water flow tends to be concentrated.Based on the relationship between air pressure and the influencing coefficient of air resistance,the calculation formula of the standardized the trajectory distance of jet was revised to provide a reference for the design of jets at high altitude.