孔板消能工具有构造方便、消能效率高以及经济等优点,在我国水电工程及泄流工程中得到广泛应用.在多级孔板设计中,孔板间距与孔板后压力恢复长度有关,而孔板后压力恢复长度的研究却很少.利用数值模拟法对孔板后压力恢复长度的影响因数进行了定量分析.结果表明,孔板后压力恢复长度主要由孔板孔径比、孔板相对厚度以及流经孔板流体的雷诺数等相关参数决定:当雷诺数增大到一个定值时,孔板后压力恢复长度几乎不随雷诺数的变化而变化;当孔板相对厚度和孔板孔径比在一定范围内,孔板相对厚度不变,孔板孔径比减小,孔板后压力恢复长度增大;当孔板孔径比不变时,孔板相对厚度增大,孔板后压力恢复长度减小.通过多元回归分析和曲线拟合得到孔板后压力恢复长度的经验公式,并进行室内试验验证,为多级孔板间距设计提供理论依据.

The orifice plate has the advantages of convenient construction, high energy dissipation efficiency, and economy, and is widely used in hydropower engineering and discharge engineering. The recovery length of the flow pressure behind the orifice plate is related to the distance arrangement between orifice plates in multi-stage orifice plate design. However, little research has been conducted on the pressure recovery length behind the orifice plate. The numerical simulation method is used to quantitatively study the influencing factors of the pressure recovery length behind the orifice plate, and the results show that the recovery length of the flow pressure behind the orifice plate is mainly dominated by the aperture ratio of orifice plate, the relative thickness of the orifice plate, and the Reynolds number of fluids flowing through orifice plate. As the Reynolds number increases to a fixed value, the pressure recovery length behind the orifice plate does not change. When the relative thickness of the aperture ratio of the orifice plate are within a certain range, the relative thickness of the orifice plate will not change, the aperture ratio of the orifice plate decreases, and the pressure recovery length behind the orifice plate increases. As the diameter ratio of orifice plate remains unchanged, the relative thickness of the orifice plate increases, and the pressure recovery length behind the orifice plate decreases. The empirical formula for the pressure recovery length behind the orifice plate is obtained by multivariate regression analysis and curve fitting, and the indoor test verification is adopted, which provide theoretical basis for distance arrangement between orifice plates in multi-stage orifice plate design.