基于滞止压力分布计算高压淹没水射流含气率

Calculation of air content of high-pressure submerged water jet based on stagnation pressure distribution

空化是高压淹没水射流的基本特征,气相的体积浓度对射流速度和侵蚀能力有重要影响。目前对空化机理研究不成熟,工程中对射流空化锥的含气率计算和定量测试均存在困难。该文基于高压淹没自由射流速度方程,射流横断面动量通量守恒和空化泡的湍流减阻效应,得出射流涡黏系数和含气率的2次方相关,经验系数α和含气率的-5/2次方相关;并建立了射流横断面含气率分布与滞止压力的关系;再根据气泡的力学平衡和功能转换,建立绝热及空间受限条件下空化含气率和速度参数的-2次方相关的关系;结合试验测得射流滞止压力,计算出射流横断面上的速度分布、含气率分布以及相关的系数c_(1)和c_(2)。该文建立了通过测滞止压力分布推算高压淹没水射流速度和含气率分布的方法。

Cavitation is the basic feature of high-pressure submerged water jets,and volume concentration of the gas phase has an important influence on jet velocity and erosion ability.At present,the research on the cavitation mechanism is immature,and there are difficulties in the calculation and quantitative test of the jet cavitation cone gas content in the project.In this paper,based on the high-pressure submerged free jet velocity equation,the momentum flux conservation of the jet cross-section and the turbulent drag reduction effect of the cavitation bubble,it is concluded that the vortex viscosity coefficient of the jet is related to the 2nd power of the gas content,and the coefficientαis related to the-5/2 power of the gas content.In addition,the relationship between the distribution of the gas content of the jet cross-section and the stagnation pressure is established;according to the mechanical balance and function conversion of the bubble,the relationsh ip between the cavitation gas content and the velocity parameter to the-2nd power under adiabatic and space-constrained condi tions is established.Combining the test to measure the stagnation pressure of the jet,the velocity distribution,gas content distribution,and related coefficients c_(1),c_(2)are calculated on the cross-section of the jet.In this paper,a method to estimate the distribution of high-pressure submerged water jet velocity and gas content is established by measuring the stagnation pressure distribution.