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在通风机和风管系统的设计中阻力损失计算是一个重要关键。其中经常遇到和难于计算的是90°矩形截面弯头的阻力损失。动力损失系数几乎与空气流速是无关的,只有对弯头来说,该系数是受风管壁的粗糙度影响,为此动力损失常与阻力损失结合起来以简化设计计算。现有数据表明,由于阻力损失与相应的阻力系数有关,弯头的动力和阻力损失用相同直风管的当量长度来表示的设计方法可认为是正确的。
Resistance loss calculations are a key consideration in the design of fan and duct systems. Often encountered and difficult to calculate is the resistance loss of 90 ° rectangular section elbow. The coefficient of dynamic loss is almost independent of the flow rate of the air. For elbows only, the coefficient is affected by the roughness of the duct wall. For this reason, the loss of power is often combined with the loss of resistance to simplify the design calculation. The available data shows that the design of the elbow loss of power and drag, expressed as the equivalent length of the same duct, is considered correct because of the resistance loss associated with the corresponding drag coefficient.