Orifice flowmeters are widely used in industry due to their simple design, ruggedness, and easy installation. However, high-pressure losses, measurement accuracy, and long pipe length requirements are still significant concerns. Typically, conical entry orifice plates at a 45-degree conical angle are recommended by orifice standards, especially for low Reynolds numbers instead of the sharp-edged orifice plates, which pose stability. The primary goal here is to develop the conical entry orifice plates further over a broader range of Reynolds numbers. In this case, a 45-degree conical angle may seem questionable since the optimization of conical angles has not been studied so far. To clarify that point and reach the new technical data about the conical entry orifice plates, orifice plates in different orifice diameter ratios (0.4, 0.5, 0.63) and beveled with different conical angles (15°, 30°, 45°) were tested numerically through water flow simulations inside a pipe with an inner diameter of 50.8 mm at different Reynolds numbers (5000,18,400, 91,100, 240,000).

According to the analysis made, the 30-degree conical angle orifice plate was the best in reducing pressure losses, resulting in pressure losses 37–52% less than that of sharp-edged orifice plates in the min-max range. Furthermore, it reduced the pressure losses by 13–21 % more than that of the 45-degree conical angle. These last outcomes indicate that current orifice standards needs a modification into the recommended conical angles. Through these findings, pressure losses in multi-hole plate flow conditioners can be reduced considerably when the holes are beveled at the 30-degree conical angle.

Also in the study, the axial characteristic lengths relevant to recirculation region, flow recovery and vena contracta were predicted approximately, along with the derived numerical correlations resulting with constants. Moreover, the effect of orifice plates exposed to an upstream distorted velocity profile on orifice flows was tested numerically. According to this evaluation, the lowest measurement errors were observed at the 30-degree conical angle orifice plate, about 30–70 % less than that of the sharp-edged orifice plate in the min-max range.

孔板流量计由于其设计简单、坚固耐用和易于安装而在工业中得到广泛应用。然而，高压损失、测量精度和长管道长度要求仍然是重要的问题。通常，孔口标准推荐采用 45 度圆锥角的锥形入口孔板，特别是对于低雷诺数而不是锐边孔板，这会带来稳定性。这里的主要目标是在更广泛的雷诺数范围内进一步开发锥形入口孔板。在这种情况下，45 度圆锥角似乎有问题，因为到目前为止还没有研究圆锥角的优化。澄清这一点，并得出关于锥形入口孔板、不同孔径比（0.4、0.5、0.

根据所做的分析，30 度锥形角孔板在减少压力损失方面效果最好，在最小-最大范围内，压力损失比锐边孔板小 37-52%。此外，它比 45 度锥角减少了 13-21% 的压力损失。这些最后的结果表明当前的孔口标准需要修改为推荐的圆锥角。通过这些发现，当孔以 30 度锥角倾斜时，多孔板流量调节器中的压力损失可以显着降低。

同样在该研究中，与再循环区域、流量恢复和静脉收缩相关的轴向特征长度以及由常数产生的导出数值相关性被大致预测。此外，还对暴露于上游扭曲速度剖面的孔板对孔板流动的影响进行了数值测试。根据该评估，在 30 度锥形角孔板处观察到的测量误差最低，在最小-最大范围内比锐边孔板的测量误差小约 30-70%。