The behavior of the fluid flowing through vertical sharp-edged orifices with the same cross-section area but different geometry was investigated experimentally on typical "large orifice" and "small orif...The behavior of the fluid flowing through vertical sharp-edged orifices with the same cross-section area but different geometry was investigated experimentally on typical "large orifice" and "small orifice".The profiles of orifice discharge coefficient curves of circular,elliptical,square,rectangular and triangular orifices were similar,and the profile of the circular one is the highest and that of the triangular one is the lowest.It can be concluded that the orifice’s geometry has some effect on orifice discharge,but it is not the key parameter,because it doesn’t change the orifice’s flow mechanism essentially.The effects of the orifice’s geometry on energy losses were evaluated based on the analysis of the hydraulic radius of orifice,interfacial tension in acute angle,and penetrating phenomenon of jet flow through non-circular orifices,which might complement the flow mechanism of the circular orifice the authors studied before.Afterwards,the orifice flow was simulated with CFD software Fluent 6.2 in order to investigate the effect of orifice’s geometry on velocity distribution and energy losses of orifice discharge.It can be seen from the simulated flow field that the geometry of orifice had little effect on the overall range and velocity distribution of the contributing flow region in front of the orifice,and the energy dissipation in front of the orifice still could be calculated by the hemisphere model.It may help to understand that the difference of mechanical energy losses in orifice flow appears after flowing into the orifice.展开更多
文摘The behavior of the fluid flowing through vertical sharp-edged orifices with the same cross-section area but different geometry was investigated experimentally on typical "large orifice" and "small orifice".The profiles of orifice discharge coefficient curves of circular,elliptical,square,rectangular and triangular orifices were similar,and the profile of the circular one is the highest and that of the triangular one is the lowest.It can be concluded that the orifice’s geometry has some effect on orifice discharge,but it is not the key parameter,because it doesn’t change the orifice’s flow mechanism essentially.The effects of the orifice’s geometry on energy losses were evaluated based on the analysis of the hydraulic radius of orifice,interfacial tension in acute angle,and penetrating phenomenon of jet flow through non-circular orifices,which might complement the flow mechanism of the circular orifice the authors studied before.Afterwards,the orifice flow was simulated with CFD software Fluent 6.2 in order to investigate the effect of orifice’s geometry on velocity distribution and energy losses of orifice discharge.It can be seen from the simulated flow field that the geometry of orifice had little effect on the overall range and velocity distribution of the contributing flow region in front of the orifice,and the energy dissipation in front of the orifice still could be calculated by the hemisphere model.It may help to understand that the difference of mechanical energy losses in orifice flow appears after flowing into the orifice.
