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孔板消能工具有结构简单和消能效率高的优点。孔板后回流区长度是孔板消能工的重要水力学参数之一,其大小不仅影响到多级孔板间距的设计,而且还影响到孔板的消能效果。此文通过理论分析和数值模拟的方法,分析了孔板水头损失系数与回流区长度的关系以及影响孔板后回流区长度的因素。研究结果表明,在雷诺数和孔板厚度不变的情况下,回流区长度随孔径比的减小而增大;在雷诺数和孔径比不变的情况下,回流区长度随孔板厚度的增加而减少;当雷诺数大于105时,回流区长度几乎不随雷诺数的变化而变化;随着回流区长度的增加,孔板的能量损失系数也增大。通过曲线拟合,此文还得到了孔板回流区长度的经验表达式。
The orifice energy dissipating tool has the advantages of simple structure and high energy dissipation efficiency. The length of the backflow zone after the orifice is one of the important hydraulics parameters of orifice energy dissipater. Its size not only affects the design of multi-level orifice spacing, but also affects the energy dissipation effect of the orifice plate. Through theoretical analysis and numerical simulation, this paper analyzes the relationship between the orifice head loss coefficient and the reflux zone length and the factors affecting the orifice backfill zone length. The results show that the length of the recirculation zone increases with the decrease of the aperture ratio under the same Reynolds number and orifice thickness. Under the same Reynolds number and aperture ratio, the length of the recirculation zone varies with the thickness of the orifice Increases and decreases. When the Reynolds number is greater than 105, the length of the recirculation zone hardly changes with the Reynolds number. As the length of the recirculation zone increases, the energy loss coefficient of the orifice increases. Through the curve fitting, this paper also obtains the empirical expression of the orifice backflow zone length.