Due to the large degree of freedom in terms of design and installation, flexible ventilation ducts are commonly used in ventilation systems. However, excessive use of flexible ducts may lead to greater pressure drop and higher energy consumption. This study conducted experimental measurements to characterize the pressure drop in flexible ventilation ducts with different compression ratios and bending angles. This investigation first measured the pressure drop in straight flexible ducts with four compression ratios under various airflow rates. The calculated friction factor for the straight flexible ducts was negatively associated with the compression ratio. Next, the pressure drops in single-bend flexible ducts with various bending angles from 30° to 150° were measured under various airflow rates. The calculated loss coefficient of the bend increased with the bending angle for single-bend flexible ducts. Finally, the influence of the intermediate duct length on the pressure drop across two bends was experimentally investigated. When the length of the intermediate duct was greater than eight times the inner diameter, the pressure drop across a double-bend flexible duct could be calculated from the friction factors and loss coefficients with a relative error less than 1%. The data obtained in this study can be used to calculate the total pressure loss in flexible ventilation ducting systems in buildings.

由于设计和安装方面的高度自由度，柔性通风管道通常用于通风系统中。但是，过度使用柔性导管可能会导致更大的压降和更高的能耗。这项研究进行了实验测量，以表征具有不同压缩比和弯曲角度的柔性通风管道中的压降。这项研究首先测量了在不同气流速率下具有四个压缩比的直形挠性管道中的压降。直管段的计算出的摩擦系数与压缩比负相关。接下来，在各种气流速率下，测量从30°到150°各种弯曲角度的单弯曲挠性管道中的压降。对于单弯挠性管道，计算得出的弯曲损耗系数随弯曲角度的增加而增加。最后，通过实验研究了中间管道长度对两个弯曲处压降的影响。当中间导管的长度大于内径的八倍时，可以通过摩擦系数和损耗系数计算出双弯挠性导管上的压降，相对误差小于1％。这项研究中获得的数据可用于计算建筑物中柔性通风管道系统的总压力损失。当中间导管的长度大于内径的八倍时，可以通过摩擦系数和损耗系数计算出双弯挠性导管上的压降，相对误差小于1％。这项研究中获得的数据可用于计算建筑物中柔性通风管道系统的总压力损失。当中间导管的长度大于内径的八倍时，可以通过摩擦系数和损耗系数计算出双弯挠性导管上的压降，相对误差小于1％。这项研究中获得的数据可用于计算建筑物中柔性通风管道系统的总压力损失。