摘要
为了深入了解文丘里施肥器喉部负压的产生条件和变化过程,通过对进出口和喉部分别有测压设计的文丘里施肥器进行有压过流试验,研究了水流在不同特征断面处的能量转化关系.对于试验用文丘里施肥器,试验结果表明:当压力水流通过时,进口处的压能将转化成喉部处的动能,随着进口压能和流量的不断增大,喉部动能增大,喉部的压能完全消失,局部开始产生负压,负压达到最小值后,继续增大进口压力水头将不再引起喉部负压值的变化,但流速的增幅明显增大,喉部动能随流量的增加呈抛物线形趋势增大,产生的水头损失急剧增大;对于同一流量,喉部实际流速与理论流速的差异反映了喉部对应断面处的真空空间的大小;相对于自由出流,非自由出流条件下,喉部开始产生负压时对应的进口起点压力提高,流量相对较大,产生相同负压时的进口压力和流量明显高于自由出流条件.
To understand the causal conditions and processes of negative pressure in the throat of Venturi injector,by measuring pressures at the inlet,outlet and throat for Venturi injector respectively,the energy conversion relations of water flow at different feature sections were studied.The results show that the inlet pressure energy is translated into the throat kinetic energy when water flows through the Venturi injector.As the inlet pressure energy and the discharge increase,the kinetic energy in the throat increases,when the kinetic energy in the throat reaches a certain value,the pressure energy at the throat disappears completely and the negative pressure occurs.When the negative pressure reaches the minimum value and remains stable,the flow velocity increases significantly as the inlet pressure increases.The kinetic energy and head loss in the throat also increases very quickly as the flow rate increases.At the same flow rate,the differences between actual and theoretical flow velocity could indicate the size of throat vacuum space.Compared with free-outflow conditions,under non-free-outflow conditions,the starting pressure causing the negative pressure in the throat increases,and the flow vo-lume is relatively great.To obtain the same negative pressure,the inlet pressures and flow rate under non-free-outflow conditions are significantly greater than those under free-outflow conditions.
出处
《排灌机械工程学报》
EI
北大核心
2013年第6期528-533,共6页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家863计划项目(2011AA1005A4)
关键词
文丘里施肥器
能量转化
喉部负压
流量
流速
Venturi injector
energy conversion
throat negative pressure
flow rate
flow velocity
