Bernoulli Pressure Lowering

伯努利压力降低

The linear drop in fluid pressure is according to Poiseuille's law, but the constriction produces and extra drop in pressure according to the Bernoulli Principle.

流体的压强线性下降根据泊肃叶定律，但狭窄处根据伯努利原理产生额外的压强下降。

Remove venturi

移除文丘里管

The liquid column height is a measure of the fluid pressure at that point in the flow tube. The vertical tubes act as manometers. The manometers show that the pressure is lowered at the constriction relative to what it would have been in a uniform tube. The pressure that drives the fluid through the tube is the static fluid pressure at the bottom of the reservoir. The resistance to flow represented by the tube causes a drop in pressure as you proceed along the tube.

液体柱的高度是流体在流动管中某一点压力的度量。垂直的管子起着 manometers 的作用。manometers 显示，在狭窄处的压力比在均匀管中时要低。推动流体通过管子的压力是储水箱底部的静压。管子所代表的流动阻力导致沿管子流动时压力下降。

When a positive pressure is applied to a tube with a constriction, the pressure in the constriction is lowered compared to that in the larger tube. This is demonstrated at left in three vertical tubes that are attached to a glass venturi tube. The middle tube is attached at the constriction. The air pressure tends to push the liquid in the tubes downward, so the higher water level in the center tube indicates that the pressure is lower there.

当正压施加到有缩颈的管子上时，缩颈处的压强会比大管中的压强低。这在左侧的三个垂直管中得到演示，这些管子连接到一个玻璃文丘里管上。中间的管子连接在缩颈处。空气压强倾向于将管中的液体向下推，因此中间管中较高的水位表明该处的压强较低。

The flow in this system is from left to right, driven by a high pressure air supply. Note that the liquid level in the right hand tube is slightly higher, indicating that the pressure there is slightly less than that at the left hand tube. This is indicative of the normal pressure drop in a flowing fluid since the diameters of the top tube are the same at the left and right tubes.

该系统的流动方向是从左到右，由高压气源驱动。请注意，右侧管中的液体电平略高，这表明该处的压力略低于左侧管中的压力。这反映了流动流体中正常的压力降，因为顶部两管的直径在左侧和右侧是相同的。

More detail

Pressure Drop with Length

长度与压力降

The pressure drop as fluid flows from a container can be modeled by Poiseuille's law. The drop in fluid pressure is indicated by the liquid column heights.

流体从容器中流动时的压力降可以用泊肃叶定律来建模。流体压力的下降用液柱高度来表示。

Constrict tube

缩窄管

The liquid column height is a measure of the fluid pressure at that point in the flow tube. The vertical tubes act as manometers.The pressure that drives the fluid through the tube is the static fluid pressure at the bottom of the reservoir. The resistance to flow represented by the tube causes a drop in pressure as you proceed along the tube. The pressure drop illustrated suggests that the tube continues for some distance to the right, and you could project the line of pressure drop to imply the location of the end of the tube. At the open end of the tube, you would imply that the gauge pressure is zero, implying that the only pressure on the fluid is atmospheric pressure.

液体柱的高度是流体在流动管中某一点压力的度量。垂直的管子起着U型管的作用。推动流体通过管子的压力是储水箱底部的静压。管子所代表的流动阻力导致沿管子流动时压力下降。所示意的压力下降表明管子继续向右延伸一段距离，你可以将压力下降的线延长以推断管子末端的位置。在管子的开口端，你应假定测压值为零，这意味着作用在流体上的唯一压力是大气压力。

Index

Poiseuilles law concepts

索引泊塞定律概念

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Pressure Monitoring for a Constricted Tube

狭窄管路中的压力监测

This is a direct experimental observation of the Bernoulli effect. A high pressure air supply directs air through a glass tube which has a constriction about halfway along it. Pressure is indicated by three manometers in which the liquid level is a measure of the pressure above the liquid.

这是伯努利效应的直接实验观察。一个高压气源将空气通过一根玻璃管，该管在中间部位有一个狭窄区域。压力由三个 manometers 表示，其中液体电平是液体上方压力的度量。

The fact that the pressure in the tube past the constriction is slightly lower than the pressure before the constriction is a demonstration of fluid friction. This can be modeled by Poiseuille's law.

管子通过狭窄部分后的压力略低于狭窄部分前的 pressure，这体现了流体的摩擦。这可以由泊肃叶定律来建模。

Index

Poiseuilles law concepts

Bernoulli concepts

索引泊肃叶定律概念伯努利定律概念

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HyperPhysics ***** 力学 ***** 流体

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