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(New page: ==Confined Flows== ===Underlying Flow Regime 4-08=== ===Abstract==== The flow through a sharp-edged orifice plate mounted concentric into a pipe of constant cross-section induces a flow ...)
 
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===Underlying Flow Regime 4-08===
 
===Underlying Flow Regime 4-08===
  
===Abstract====
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====Abstract====
The flow through a sharp-edged orifice plate mounted concentric into a pipe of constant cross-section induces a flow contraction and a separation downstream of the orifice plate. The narrowest cross-section of the flow is however not located in the orifice itself, but some distance downstream (Fig. 1). The region of the narrowest cross-section is often called “vena contracta”. Further downstream of this location the flow expands again up to the pipe cross-section. Naturally, such a flow configuration is associated with a considerable pressure loss, since a great deal of kinetic energy is dissipated within the recirculation region. Therefore, such an orifice plate is often used as a flow meter mounted into a pipe (Hayward 1979). For such an application normally a special design of the orifice hole is used and the pressure tapings should be mounted at a certain distance with respect to the orifice location (Fig. 2).
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The flow through a sharp-edged orifice plate mounted concentric into a pipe of constant cross-section induces a flow contraction and a separation downstream of the orifice plate. The narrowest cross-section of the flow is however not located in the orifice itself, but some distance downstream (Figure 1). The region of the narrowest cross-section is often called “vena contracta”. Further downstream of this location the flow expands again up to the pipe cross-section. Naturally, such a flow configuration is associated with a considerable pressure loss, since a great deal of kinetic energy is dissipated within the recirculation region. Therefore, such an orifice plate is often used as a flow meter mounted into a pipe (Hayward 1979). For such an application normally a special design of the orifice hole is used and the pressure tapings should be mounted at a certain distance with respect to the orifice location (Figure 2).
  
[[Image:UFR4-08.jpg|centre|thumb|px|'''Figure 1.''' Illustration of the flow structure through a pipe with a sharp-edge orifice plate.]]
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[[Image:UFR4-08.jpg|centre|thumb|500px|'''Figure 1.''' Illustration of the flow structure through a pipe with a sharp-edge orifice plate.]]
  
[[Image:UFR4-08_a.jpg|centre|thumb|px|'''Figure 2.''' Different designs of the orifice plates used for flow meters.]]
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[[Image:UFR4-08_a.jpg|centre|thumb|500px|'''Figure 2.''' Different designs of the orifice plates used for flow meters.]]
 
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''Contributors: Martin Sommerfeld - Martin-Luther-Universitat Halle-Wittenberg''
 
''Contributors: Martin Sommerfeld - Martin-Luther-Universitat Halle-Wittenberg''

Revision as of 14:21, 2 June 2008

Confined Flows

Underlying Flow Regime 4-08

Abstract

The flow through a sharp-edged orifice plate mounted concentric into a pipe of constant cross-section induces a flow contraction and a separation downstream of the orifice plate. The narrowest cross-section of the flow is however not located in the orifice itself, but some distance downstream (Figure 1). The region of the narrowest cross-section is often called “vena contracta”. Further downstream of this location the flow expands again up to the pipe cross-section. Naturally, such a flow configuration is associated with a considerable pressure loss, since a great deal of kinetic energy is dissipated within the recirculation region. Therefore, such an orifice plate is often used as a flow meter mounted into a pipe (Hayward 1979). For such an application normally a special design of the orifice hole is used and the pressure tapings should be mounted at a certain distance with respect to the orifice location (Figure 2).

Figure 1. Illustration of the flow structure through a pipe with a sharp-edge orifice plate.
Figure 2. Different designs of the orifice plates used for flow meters.



Contributors: Martin Sommerfeld - Martin-Luther-Universitat Halle-Wittenberg