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为深入研究突扩突跌掺气设施的掺气特性,在三峡工程深孔水工模型上对时均压强分布、掺气量、掺气浓度等进行了观测与分析。试验结果表明在侧墙形成4个区域,即:侧空腔区、压强骤变区、低压区和稳定区,侧空腔长度和侧墙时均压强均与折流器高度有关。在侧墙低压区有负压存在,其发生位置一般距孔口出口(等高程)约15m左右。在侧墙有少量掺气,掺气浓度在1.3%左右,掺气的主要原因是侧墙冲击点处产生的立轴漩滚对空气的卷吸作用。侧向折流器对掺气量有明显影响。侧、底空腔贯通时,侧空腔是一个重要的通气通道,是保证底空腔充分掺气的重要条件。此研究成果和结论可供突扩突跌掺气坎的设计和科研参考。
In order to further study the aeration characteristics of the sudden expansion and contraction aeration facilities, the time-average pressure distribution, aeration volume and aeration concentration were observed and analyzed in the deep hole hydraulic model of the Three Gorges Project. The test results show that there are four regions in the side wall, namely side cavity area, sudden pressure change area, low pressure area and steady area. The length of side cavity and the average pressure of side wall are related to the height of deflector. Negative pressure exists in the low pressure area of the side wall, and its place of occurrence is generally about 15m away from the orifice exit (equal elevation). There is a small amount of aeration in the side wall, aeration concentration of about 1.3%, the main reason for aeration is the vertical axis of the wall impact point of the whirling roll on the role of air entrainment. Lateral baffles have a significant effect on aeration. When the side and bottom cavities pass through, the side cavity is an important ventilation channel, which is an important condition for ensuring that the bottom cavity is fully aerated. The results and conclusions of this study can be used for the design and scientific reference of sudden expansion and contraction aeration.