orifice coefficient

例句：

1. 1.The orifice coefficient of the pipe is an important factor in determining its flow capacity.
   管道的孔口系数是决定其流量容量的重要因素。
2. 2. The orifice coefficient can be used to predict the pressure drop across a fluid passage.
   孔口系数可以用来预测流体通道的压力降。
3. 3. The orifice coefficient is calculated using the formula: Cv = Q / (4πr²).
   孔口系数的计算公式为：Cv = Q / (4πr²)。