关键词:

孔前流动影响区, 机械能损失, 孔流系数

Abstract:

The experiments on the characteristics of the fluid discharging through the streamlined contractive orifice and the vertical sharp-edged orifice with same diameter were carried out.The mechanical energy loss of the fluid flowing in front of vertical sharp-edged orifice was imitated by that of the fluid through the streamlined contractive orifice, which was compared with the mechanical energy consumed in the whole orifice discharge process through vertical sharp-edged orifice.Thus, the proportion of the upstream mechanical energy loss to total mechanical energy loss can be obtained quantitatively with respect to typical “large orifice” and “small one” at different operating conditions.The proportion reflects the difference of the mechanical energy consumed inside orifice between large orifice and small orifice, as well as the effects of the plate thickness.Moreover, the flow mechanism of orifice discharge proposed in the study before this work was verified.Afterwards, according to the physical model of the contributing flow region in front of orifice and the data of the flow field simulated with computational fluid dynamics (CFD) software Fluent 6.2 before this work, the basic mode of equation on the resistance coefficient of the contributing flow region in front of orifice was obtained.Therefore, the model of mechanical energy consumed upstream at fully developmental turbulent regime was founded by simulated the experimental data.

Key words:

孔前流动影响区, 机械能损失, 孔流系数