通风管道沿程局部阻力的计算

发布人：http://www.sftfgd.com   发布时间：2018-01-03 17:23:06

当空气流动断面变化的管件（如各种变径管、风管进出口、阀门）、流向变化的管件（弯头）流量变化的管件（如三通、四通、风管的侧面送、排风口）都会产生局部阻力。

When the air flow section changes tube parts (such as all kinds of variable diameter pipes, air pipes, inlet and outlet, valves), pipes that flow to change (elbow) flow rate of pipe fittings (such as three way, four way, side pipe and air outlet) will produce partial resistance.

局部阻力按下式计算：

Local resistance press formula:

Z=ξν2ρ/2

V 2 P /2 Z=.

ξ――――局部阻力系数。 局部阻力在通风、空调系统中占有较大的比例，在设计时应加以注意，为了减小局部阻力，通常采用以下措施：

Zeta -- local resistance coefficient. Local resistance occupies a large proportion in ventilation and air conditioning systems. Attention should be paid to the design of local resistance. In order to reduce local resistance, the following measures are usually adopted.

1. 弯头 布置管道时，应尽量取直线，减少弯头。圆形风管弯头的曲率半径一般应大于（1~2）倍管径；矩形风管弯头断面的长宽比愈大，阻力愈小；矩形直角弯头，应在其中设导流片。

When the 1. elbow is arranged, the line should be taken as far as possible to reduce the elbow. The radius of curvature of the circular duct elbow generally should be greater than (1~2) times the diameter; rectangular duct elbow section length to width ratio is, the smaller the resistance; rectangular elbow, should be set up in the deflector.

2. 三通 三通内流速不同的两股气流汇合时的碰撞，以及气流速度改变时形成的涡流是造成局部 阻力的原因。为了减小三通的局部阻力，应注意支管和干管的连接，减小其夹角；还应尽量使支管和干管内的流速保持相等。

2. the collision of the two - strand air flow with different flow velocity in the three pass and three through, and the eddy formed when the velocity of the air flow is changed is the cause of the local resistance. In order to reduce the local resistance of the three pass, attention should be paid to the connection of the branch pipe and the dry pipe to reduce the angle of the pipe; the flow rate in the pipe and the dry pipe should be kept as equal as possible.

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